Lower Tertiary 

Crinoids from 

Northwestern Oregon

GEOLOGICAL SURVEY PROFESSIONAL PAPER 233-E
Lower Tertiary 

Crinoids from 

Northwestern Oregon

By RAYMOND C. MOORE and HAROLD E. YOKES

SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1950-1951, PAGES 113-148

GEOLOGICAL SURVEY PROFESSIONAL PAPER 233-E

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1953
UNITED STATES DEPARTMENT OF THE INTERIOR 

Oscar L. Chapman, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director

For sale by the Superintendent of Documents, U. S. Government Printing Office 

Washington 25, D. C. - Price $1.00
CONTENTS

Page 

Abstract_________________________________________ 113

Introduction _______________________________________ 113

Discov.ery of crinoid remains in Oregon.___________ 113

Occurrence of Tertiary crinoids elsewhere in the

Western Hemisphere._________________________ 116

Acknowledgments__ ___________________________ 118

The Oregon crinoid-bearing beds____________________ 118

Lithologic and paleontologic characters of the Keasey

formation.___________________________________ 118

Age of the Keasey formation.____________________ 119

Outcrops of the Keasey formation from which crinoid 

remains have been collected.____________________ 120

Description of crinoids_____________________________- 120

Material available for study____________________ 120

Suprafamilial placement of the Oregon crinoids_____ 121

Family Isocrinidae GislSn, 1924________________ 121

Genus Isocrinus von Meyer, 1837_________________ 122

Characters of Isocrinus-. ____________________ 122

Comparison with related"genera______________ 123

Isocrinus oregonensis Moore and Yokes, n. sp_____ 124

Summary of description____________________ 124

Description of specimens___________________ 124

Holotype._--------_-----_------_-_--__ 124

Paratypes____________________________ 124

Page

Description of crinoids—Continued 

Isocrinus oregonensis—Continued

Dorsal cup_---_----_--------_----_--------- 128

Rays, exclusive of radials. ___________________ 130

Column. ___________________________ 132

Discussion _________________________________ 134

Isocrinus nehalemensis Moore and Yokes, n. sp_____ 135

Summary of description.____________________ 136

Description of specimens___________________ 136

Holotype—.____________________ 136

Paratypes.____________________________ 136

Dorsal cup_______________________________ 136

Ray structure-_____-------_--_-_-___---____ 136

Column. _ _____________________________ 138

Discussion. ________________________________ 139

Species of Isocrinus described from Tertiary rocks in other

parts of the world _________________________________ 139

Paleoecology of the Keasey crinoids.__________________ 140

General statement-_______-_-------___-______-__ 140

Physical features_______________________________ 140

Organic evidence.______-_--__-_-___-_-_-___--__ 141

References-________--__--_-----------_---_--------_ 142

Index-______-______----------------_-----_-------_ 145

ILLUSTRATIONS

[Plates 14-24 follow index] 

PLATES 14—18. Isocrinus oregonensis

19, 20. Isocrinus oregonensis and /. nehalemensis

21. Crinoid locality near Mist, Oregon, and Isocrinus nehalemensis

22. Isocrinus nehalemensis, I. oregonensis, and associated plant remains

23. Isocrinus columnals from the Keasey formation, Oregon

24. Isocrinus oregonensis

FIGURE 27. Maps of upper Nehalem basin, northwestern Oregon, showing crinoid localities.______________________

28. Columnar section of the Keasey formation________________________-______-_--------_-----_-------

29. Holotype of Isocrinus oregonensis.--------------------------------------------------------------

30. Paratype A of Isocrinus ore<7<me«s*s_________________________________--_-----------------_-------

31. Ray structure of paratype A of Isocrinus oregonensis----------------------------------------------

32. Paratype B of Isocrinus oregonensis and diagram of ray structure____________--__---_--------_--__--

33. Ray structure of paratype L of Isocrinus oregonensis..---------------------------------------------

34. Brachials and pinnules of the holotype of Isocrinus oregonensis --------------------------------------

35. Paratypes of Isocrinus oregonensis in collections of the University of California Museum of Paleontology.

36. Isocrinus columnals___-_____________________________________________------__---------------_--

37. Paratype C of Isocrinus nehalemensis------------------------------------------------------------

38. Ray structure of holotype and two paratypes of Isocrinus nehalemensis------------------------------

39. Radial plates and syzygial articulation of Isocrinus nehalemensis and cirrus socket of I. oregonensis-----.

Page

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136

137

138

in

LOWER TERTIARY CRINOIDS FROM NORTHWESTERN OREGON

By RAYMOND C. MOORE AND HAROLD E. VOKES

ABSTRACT

The occurrence of numerous remains of crinoids, including 

nearly complete crowns, in the middle member of the Keasey 

formation, early Tertiary, of northwestern Oregon is of more 

than ordinary paleontological interest. Most of the marine 

Tertiary formations of North America are notably lacking in 

crinoids, although in a few places abundant fragmentary remains of free-swimming crinoids (comatulids) have been reported. Only five species have been described from North 

America, exclusive of the West Indies. Five more species, distinguished on the basis of stem fragments, are reported from 

Eocene rocks of Trinidad and Miocene deposits of Haiti and 

Cuba.

The Oregon crinoids here described are stem-bearing forms, 

assigned to the genus Isocrinus. They constitute the firstreported occurrence of this type of crinoid in the Tertiary of 

the continent. It is especially interesting to find nearly complete crowns that rival some of the well-known pentacrinid 

crowns from Jurassic localities in Europe. However, the Oregon fossils generally have the hard parts poorly preserved, and 

some of the best preparations for study of their structure consist of external molds. A few of the molds were formed by 

natural weathering, but most have been prepared by etching 

the partly decomposed calcite with acid.

On the basis of more than a dozen crowns, some fairly complete, and innumerable fragments of stems, arms, and pinnules, 

two species are recognized. They are named Isocrinus oregonensis and /. nehalemensis. Some fossils, preserved as calcite, are assigned to each species, but most of the specimens 

are molds.

The Keasey formation includes deposits belonging to the uppermost Eocene and lower Oligocene. Analysis of the molluscan 

fauna, which is associated with the crinoids in the middle member of the Keasey formation, indicates that the crinoid-bearing 

beds are probably of early Oligocene age.

The matrix in which the fossils are embedded is a highly 

tuffaceous, mostly fine-grained, hard, massive siltstone. Locally, it contains scattered ash "pebbles" % in. or more in 

diameter. The articulated condition of most of the crinoid 

material indicates very quiet water sedimentation, which certainly does not belong in a wave-agitated, near-shore zone. 

That land was not far away from the sites where crinoids were 

buried during Keasey sedimentation, however, is indicated by 

the ash "pebbles" and especially by occurrence of well-preserved 

land plants, which are mingled with the mollusks and crinoids. 

The environment of deposition, accordingly, is interpreted to 

denote moderately deep water- adjacent to a land on which 

explosive-type volcanic activity existed during at least middle 

and late times of deposition. That the area in which the 

crinoids lived and were buried was a sound seems more likely 

than that it was open ocean.

INTRODUCTION 

DISCOVERY OF CRINOID REMAINS IN OREGON

The remarkable crinoid specimen, which constitutes 

the holotype of the new species Isocrinus oregonensis,

was collected in 1944 by Walter C. Warren and Eex M. 

Grivetti, at that time members of a field party of the 

United States Geological Survey engaged in preparation of a reconnaissance geologic map of northwestern 

Oregon (Warren, Grivetti, and Norbisrath, 1945), 

The specimen was found in a stratum of the Keasey 

formation (figs. 27, 28) exposed a short distance above 

the level of the Nehalem Eiver in a prominent bluff 

located on the west side of that river approximately 

3,500 feet south of the junction of Oregon State highways 47 and 202 at Mist, Columbia County, Oreg. 

(U. S. Geol. Survey locality 15318). This site has long 

been known as a fossil locality, first described by Diller 

in 1896 (pp. 469-470). Schenck (1936, p. 58) recognized it as being probably the type locality of Acila 

(Truncacila) nehalemensis G. D. Hanna, one of the 

principal guide fossils of the Keasey formation.

Crinoid material is not uncommon in a thin zone at 

this outcrop, and crinoid specimens are known to be in 

the hands of amateur collectors from the Portland area. 

A few fragmentary specimens are in the collections at 

Oregon State College, Corvallis, Oreg.

In view of the absence of known stem-bearing crinoids 

in Tertiary deposits of North America outside of Oregon, and of the fact that the occurrence of crinoids at 

the Columbia County locality was fairly well known 

locally some time before collection of specimens by the 

U. S. Geological Survey party, it is rather surprising 

that these fossils have not been reported earlier. If 

west coast paleontologists knew of the Keasey crinoids 

they must not have apprehended the extreme rareness 

and fragmentary condition of described stem-bearing 

crinoids elsewhere in Tertiary deposits of the world. 

The fossils are important because of the very meager 

record of stem-bearing crinoids in North America between Late Cretaceous and the present time.

In addition to the relatively complete crowns described from the locality near Mist, crinoid stem segments occur at four other localities in the Keasey formation. The material from three of them agrees with the 

more abundant stem segments found in association with 

the crowns at U. S. Geological Survey locality 15318 

and is referred to Isocrinus oregonensis. Columnals 

from the fourth locality are unlike the common ones 

in the other collections and are considered to represent 

a different form, here called 7. nehalemensis. Stem 

fragments were found also in coarse sandstones of the

113
114 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1950-51

EXPLANATION

Volcanics

A

Isocrinus calices 

and columnals

Isocrinus columnals 

only

Contact

Contact,

approximately

located

Contact, 

uncertain

or 

<

HOd 

LJ

r-

[ASHINGTON

«TORIA

5 Miles

FIOUBE 27.—Map of upper Nehalem basin, northwestern Oregon, showing localities that yielded crinoids.
LOWER TERTIARY CRINOIDS FROM NORTHWESTERN OREGON 115

Member

Upper

Middle

Lower

Thickness 

(feet)

250

120

250

40-500

Description

120 Interbedded gray tuffaceous shale and fine-grained tuffaceous s 

sandstone with a few thin beds of fine tuff; sparingly fossiliferous; fauna includes Lima (Acesta) oregonensis Clark, Nemocardium lorenzanum (Arnold), Porterius gabbi (Dickerson). 

Turcicula n. sp., Gyrineum jeffersonensis Durham.

Approximate horizon of occurrence of crinold calyces at Mist,

Oregon. :-i->z->;-i->_-_ 

335 Gray tuffaceous mudstone with a few thin tuff beds, and scattered taaaseasK^ 

bands of fossiliferous calcareous concretions. Scattered fos- ^^^_- ___. 

sils; fauna includes Acila (Truncacila) nehalemensis Hanna, i^^-i-i*-: 

Nemocardium weaveri (Anderson and Martin), Thracia n. sp., __ 

Tellina n. sp., Oleguahia schencki Durham, Nekewis n. sp., t-=-=-=-=-=-i-c-i-: 

Flabellum hertleini Durham, Eumorphocorystes naselensis 

Rathbun, etc.

125 Gray, firm, well-stratified tuffaceous shale with thin tuff bands. 

Fauna includes Acila (Truncacila) nehalemensis Hanna, 

Nemocardium weaveri (Anderson and Martin), Tellina n. sp., 

Echinophoria "dalli var." Durham, Epitonium condoni (Dall) 

n. var., etc.________________________________

100 Gray, unstratified, tuffaceous mudstone with thin tuff bands.

Fauna includes Acila (Truncacila) nehalemensis Hanna, t-i-c-*-: 

Nemocardium weaveri (Anderson and Martin), Tellina n. sp., 

Epitonium keaseyense Durham, "Gemmula" bentsonae Durham, etc.

480 Gray, unstratified, tuffaceous and sandy mudstone, (mostly con- ggsSfe^&ss 

cealed) with occasional thin tuff beds, and scattered bands 

of dark, calcareous concretions, many containing large numbers of Delectopecten n. sp. A large and heterogeneous fauna __._,__,_ 

includes Acila (Truncacila) nehalemensis Hanna, Nemocardium '^^^^^^ 

weaveri (Anderson and Martin), Thracia n. sp., Tellina n. sp., ll^ppjeg 

Epitonium keaseyense Durham, Epitonium condoni (Dall), n. var., ^jigliisSgs 

Echinophoria "dalli var." Durham, Bruclarkia n. sp. Nekewis 

n. sp. "Gemmula" bentsonae Durham, Eumorphocorystes naselensis Rathbun.

Gray, unstratified, tuffaceous mudstone with occasional concretionary bands. A large fauna includes Acila (Truncacila) 

nehalemensis Hanna, Crenella porterensis Weaver, Nemocardium 

weaveri (Anderson and Martin), Thracia n. sp., Tellina n. sp., 

Echinophoria "dalli var." Durham, Olequahia schencki Durham, 

Bruclarkia n. sp., Cancellaria n. spp., "Gemmula" bentsonae 

Durham, Turritetta n. sp., Nekewis n. sp., Isocrinus columnals.

Gray tuffaceous shale with a few concretionary bands. Sparsely 

fossiliferous.

Gray, unstratified, tuffaceous mudstone. Fossiliferous; fauna 

includes Acila (Truncacila) nehalemensis Hanna, Delectopecten 

n. sp., Nemocardium weaveri (Anderson and Martin;, Thracia 

n. sp., Tellina n. sp., "Gemmula" bentsonae Durham.

^|3fe3$giS

(Thicker toward north). Dark gray, glauconitic sandy shales 

and siltstones. A thin pebble conglomerate at base. Fossiliferous; fauna includes Acila (Truncacila) nehalemensis Hanna 

(rare), Solemya wittapaensis Weaver, Thyasira n. sp., aff. T. 

disjuncta Gabb, Pitar clarki (Dickerson), Turcicula columbiana 

Dall, Conus n. sp. "Zanthopsis" vulgaris Rathbunn.

FIGTIBE 28.—Composite columnar section of the Keasey formation, Washington and Columbia Counties, Oregon. It is based mainly on exposures of the formation in cuts 

along the Wolf Creek Highway (Oregon route no. 2) in the vicinity of Sumset Tunnel.
116 SHORTER CONTRIBUTIONS TO GEOSTEKAL GEOLOGY, 1950-51

Toledo formation exposed in sea cliffs north of Yachats, 

Lincoln County, Oreg. Both kinds of columnals occur 

at the Mist and Yachats localities.

In 1946, the junior author and Mr. P. D. Snavely, Jr., 

visited the locality on the Nehalem River and collected 

several large chunks of rock showing traces of crinoids 

along the edges. At least 50 pounds of the material 

was shipped to the senior author at the University of 

Kansas.

During the 1949 field season, Oregon fossil localities 

in the Keasey formation were visited by the junior 

author with Dr. J. Wyatt Durham of the University of 

California. Crinoid material collected at the Mist outcrop on Nehalem Eiver (U. S. Geological Survey locality 15318) consisted mostly of unaltered calcite embedded in hard unweathered rock. At least four dorsal 

cups and attached lower parts of the arms were obtained, together with blocks containing arm and stem 

fragments. Efforts made at the University of California to prepare these fossils by breaking down the 

matrix with caustic potash were only partly successful, 

as it was found almost impossible to avoid some corrosion of the calcite of the fossils. Therefore, the 

potash method was abandoned. Through kindness of 

Dr. Durham, eight University of California specimens 

(marked Loc. A5018) were loaned to the senior author 

for study, with permission to make further preparation 

of the material. This has been done, working with 

sharp tools under the binocular microscope, but much 

time was required, owing to hardness of the matrix. 

The fossils, which are preserved as calcite, importantly 

supplement studies previously made on external molds, 

but many details of structure, such as the syzygial union 

of various brachials, are less readily and reliably determinable on the University of California specimens than 

on the molds belonging to the U. S. Geological Survey 

collection. Kesults of study of the University of California specimens have been incorporated in the report.

Casts of portions of the stem of Isocrinus oregonensis 

are very abundant at U. S. Geological Survey locality 

15314; some attain lengths up to 60 mm, and many exhibit cirri. An excellently preserved specimen showing 

a nodal segment and seven interodals of various orders 

(pi. 23, figs. 1-3) was collected at U. S. Geological 

Survey locality 15282, and a single concretion, from 

U. S.* Geological Survey locality 15508, yielded several 

disassociated stem segments (pi. 23, figs. 5, 6, 8-10).

Specimens of columnals referred to Isocrinus nehalemensis (pi. 23, figs. 4, 7, 11) were collected from U. S. 

Geological Survey locality 15268, from beds approximately 40 feet stratigraphically above those at 15508 

that yielded stem segments of /. oregonensis.

OCCURRENCE OF TERTIARY CRINOIDS ELSEWHERE 

IN WESTERN HEMISPHERE

The almost complete absence of known crinoid remains from Tertiary deposits of the Americas has been 

indicated by Springer (1925, pp. 4-6). In this paper, 

describing a few crinoid stems from Miocene deposits 

of Haiti (Bcdwnocrinus haitiensis Springer), he writes:

That which does give to our species a very special interest 

is the fact that its occurrence in the Miocene of the West Indies 

furnishes a notable addition to the extremely small number 

of Tertiary crinoids that are known. When we consider the 

vast extent of Eocene and Miocene sedimentaries of marine 

origin in Europe, Asia, Africa, Australia, the United States, 

West Indies, Central and South America, many of them thousands of feet in thickness and richly fossiliferous, abounding in 

crustaceans, corals, mollusks, and other organisms everywhere 

associated with crinoids, in ages preceding the Tertiary as 

well as in the present seas, it is remarkable how few are the 

remains of crinoids which they have yielded. About 40 species, 

embraced in 8 or 9 genera, will cover all that have been described, most of them from very imperfect material, such as 

isolated columnals of pentacrinites and centrodorsals of comatulids, among which are doubtless a number of synonyms. 

Well-preserved specimens, such as are so frequent in the Jurassic and Cretaceous, are almost unknown in the Tertiary, about 

all we know of the crinoid life of that age being derived from 

the fragmentary remains above mentioned, and even these are 

of rare occurrence.

Of the restricted number of species hitherto known, only a 

single one has been derived from American rocks [true at the 

time of Springer's writing], namely, the cup of a small comatulid 

belonging to the Thalassometrinae from the Eocene of North 

Carolina, described by Emmons [1858, p. 311, figs. 246, 247] as 

Microcrinus conoideus. A few other fragmentary remains, not 

hitherto noted or described, occur in the same beds, and specimens of a species of comatulid, Nemaster, have been found in 

the Eocene of South Carolina—all fragmentary and extremely 

rare amid a profusion of other fossils.

Up to the present time, 12 species of crinoids have 

been described from Tertiary rocks of the Western 

Hemisphere. Five of these are diminutive comatulids, 

described on the basis of specimens consisting of radials and centrodorsal or of brachial plates. The other 

7 described species are stem-bearing forms, and all but 

one of these are known only from isolated stem fragments. The names of these crinoids, together with 

their stratigraphic occurrence and known geographic 

distribution, are indicated in the following list.

Tertiary crinoids reported from Western Hemisphere

Comatulids

Glenotremites (Palaeantedon) caroliniana Gislen (1934,

pp. 57-59, figs. 49-59, 61), Eocene (Jackson), near Baldock, S. C. 

Himerometra lassleri Gislen (1934, pp. 14, 49-52, figs. 1-36),

Eocene (Jackson), near Baldock, S. C. 

Cypelometra iheringi ( de Loriol, 1902, p. 22, pi. 2, figs. 3-4 ;

Gislen, 1924, pp. 107, 116, 159, 191), Eocene, Oligocene, or

Miocene, Patagonia, South America. 

Microcrinus conoideus Emmons (1858, p. 311, figs. 246, 247).

Trent marl, Miocene, Craven County, N. C.
LOWER TERTIARY CRINOIDS FROM NORTHWESTERN OREGON 117

Microcrinus sp. cf. M. conoideus Emmons (Gisl6n, 1934, pp. 

54-56, figs. 38-47), Eocene (Jackson), near Baldock, S. C.

Unnamed and undescribed comatulids (Howe, 1942, pp. 

1194-1195, figs. 10-11, 19-20), Eocene (Jackson), Alabama ; Oligocene (Red Bluff), Alabama, Mississippi. 

Stem-bearing articulates

"Pentacrinus" obtusus Guppy (1874, p. 444, pi. 18, fig. 26), 

isolated columnals only, Eocene, Trinidad.

"Pentacrinus" rotularis Guppy (1874, p. 444, pi. 18, fig. 25), 

isolated columnals only, Eocene, Trinidad.

"Pentacrinus" bryani Gabb [">=Balanocrinus] (1876, p. 178, 

pi. 5, fig. 18b), isolated stem fragments only, Vincentown 

limesand, Eocene (Wilcox?), New Jersey.

Balanocrinus haitiensis Springer (1925, pp. 2-8, pi. 1, figs. 

1-10), articulated groups of columnals only, lower Miocene, Haiti.

Balanocrinus cubensis Valette (in Sanchez-Roig, 1926, pp. 

19-20, pi. 1, figs. 4-5), isolated columnals only, lower 

Miocene, Cuba.

Austinocrinus cubensis Valette (in Sanchez-Roig, 1926, pp. 

21-22, pi. 1, fig. 3), isolated columnals only, Miocene (?), 

Cuba.

Bourgueticrinus cylindricus (Weller) (1907, pp. 275-276, 

pi. 6, fig. 1), dorsal cup, Vincentown limesand, Eocene 

(Wilcox?), New Jersey.

The above list of crinoid species contains two stembearing forms from the Vincentown sand of the Rancocas group of New Jersey. This stratigraphic unit 

has been classed during many years as uppermost Cretaceous. Clark and Twitchell (1915) described and 

figured Vincentown crinoids as Cretaceous fossils. 

These include stem fragments of "Pentacrinus" bryani 

Gabb (Clark and Twitchell, pp. 35-36, pi. 6, fig. 2a, b), 

Weller's type of Rhizocrinus cylindricus, and several 

columnals inferred to belong to this species (Clark and 

Twitchell, p. 40, pi. 7, figs. 5a-g). Characters of the 

articular facets indicate that Gabb's species probably 

belongs to Balanocrinus (proximal columnals), and according to Gislen (1938, p. 7, fig. 6), Weller's species 

should undoubtedly be assigned to Bourgueticrinus. 

Canu and Bassler (1933), in describing the rich bryozoan fauna (some 65 species) of the Vincentown beds, 

reported close resemblance of this assemblage to abundant bryozoans occurring in the Danian rocks (presumed to be uppermost Cretaceous) of Denmark, and 

accordingly they affirmed judgment of the Cretaceous 

age of the Vincentown deposits.

The Vincentown sand was assigned to the Eocene by 

Cooke and Stephenson (1928) largely on the presence 

of Venericardia. Greacen (1941), from a review of 

the stratigraphy and fauna of this formation, concludes 

that it should be assigned to the Paleocene or possibly 

the Eocene. Cooke, Gardner, and Woodring (1943, 

pi. 1) adopt the view of Cooke and Stephenson in correlating the Vincentown with Wilcox group of the 

Eocene. This age determination is accepted, but whatever its age, the crinoid remains are an extremely rare 

element of its fauna.

997130—53———2

It is of interest now to review briefly what is known 

of crinoid remains of undoubted Tertiary age elsewhere 

in the Western Hemisphere.

The first reported crinoid is the small comatulid 

called Microcrinus conoideus Emmons (1858). This 

is the only Cenozoic crinoid listed in the Clark and 

Twitchell (1915) memoir, but because they were unable 

to find a specimen, no illustration was given. They reported it (p. 112) as occurring in the "Trent marl 

(middle Eocene) of Craven County, N. C." This deposit is classed by Cooke, Gardner, and Woodring 

(1943) as lowest Miocene. Until additional specimens 

of this fossil from a known horizon and locality are 

collected, its nature and stratigraphic significance must 

be in doubt. Clark and Twitchell (1915, p. 112) designated it as Zenometra(f) conoideus.

Beds of Eocene (Jackson) age near Baldock, S. C., 

are rich in comatulid ossicles, which include centrodorsals, radials, and brachials. Gislen (1934) sorted 

out some 23,000 comatulid ossicles during his study of 

this material. Mainly from examination of the types 

of arm branching, Gislen was able to differentiate and 

reconstruct three species—one designated as Microcrinus cf. conoideus Emmons and two new species, 

Grlenotremites (Palaeantedon) caroliniana and Hiinerometra l)assleri.

Howe (1942) reports abundant comatulid remains in 

Eocene and Oligocene rocks of the Gulf Coastal Plain 

from Alabama to Mississippi, and he figures a number of specimens, but without description or designation 

by name. All are microcrinoids. Howe notes that 

forms occurring in different zones can readily be 

differentiated.

Other Tertiary crinoids known from the Western 

Hemisphere are all reported from areas south of the 

United States. De Loriol (1902) described a comatulid, Oypelometra iheringi, from rocks doubtfully referred to Eocene, Oligocene, or Miocene in Patagonia. 

This fossil is discussed by Gislen (1924, pp. 107, 116, 

159,191).

Isolated columnals of a pentacrinid were collected 

from Eocene rocks of Trinidad and described as Pentacrinus [1—Isocrinus~\ olbtusus Guppy (1874) and Pentacrinus [1=Isocrinus~\ rotularis Guppy (1874).

Springer (1925) described and figured half a dozen 

stem fragments, which he named Balanocrinus haitiensis from lower Miocene rocks of Haiti, West Indies.

Stem fragments referred to a new species called 

Balanocrinus cubensis Valette (in Sanchez-Roig, 1926) 

have been described from lower Miocene rocks of Cuba. 

In the same paper, other types of stem fragments were 

named Austinocrinus cubensis Valette, from rocks in 

Cuba doubtfully identified as Miocene.

This review reveals that nowhere in North or South 

America have Tertiary crinoid fossils been found that
118 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1950-51

are comparable to those described in this paper from 

the Tertiary rocks of Oregon. Also, the Oregon 

crinoids are the only undoubted representatives of Isocrinus yet recorded in the Western Hemisphere. The 

stem fragments described from Trinidad by Guppy may 

belong to Isocrinus, but this is uncertain. Furthermore, a survey of Tertiary crinoids from other parts of 

the world fails to show comparable specimens, excepting 

a nearly complete crown of Balanocriruus subbasaltiformis Sowerby, described by Sieverts-Doreck (1943) 

from the Eocene (London clay) of England.

ACKNOWLEDGMENTS

Special thanks are expressed to Dr. J. Wyatt Durham, University of California, at Berkeley, for the opportunity to study specimens of Keasey crinoids from 

Oregon in the collections of the Museum of Palaeontology of that institution.

Suggestions received from Dr. Hertha SievertsDoreck, of Stuttgart, Germany, have been very helpful 

and are much appreciated. Her presence at the University of Kansas at the time the present manuscript 

and illustrations were being reviewed was fortunate, 

for few specialists in the study of fossil articulate 

crinoids have wider knowledge and experience in research on these forms.

THE OREGON CRINOID-BEARING BEDS

LITHOLOGIC AND PALEONTOLOGIC CHARACTERS OF 

THE KEASEY FORMATION

Warren and Norbisrath (1946, pp. 213-237) have 

summarized the stratigraphy of the Upper Nehalem 

Basin in northwestern Oregon, including a description 

of the Keasey formation from which crinoid remains 

have been collected. They divide the Keasey strata, 

which are named from outcrops on Rock Creek in the 

Nehalem area, into three lithologically and faunally 

distinct members.

(1) A lower member, 500 feet thick at the type locality of the formation, but thinner toward the south, consists of dark-gray, generally glauconitic, fossiliferous 

shales. A fauna of approximately 50 species has been 

obtained from these beds. The most characteristic 

forms confined to this member are Turcicula columbiana 

Dall, Fimbria washingtoniana (Clark), and a new 

species of Conus. A new species of Thyasira, which is 

very abundant here, is rarely present also in the fauna 

of the middle member.

(2) The middle member is marked faunally by Nemocardium weaveri (Anderson and Martin), OlequaMa, 

schencki Durham, Thracia n. sp., Nekewis n. sp., and a 

new variety of Epitonium condom Dall, which are confined to this part of the Keasey formation. The member is distinguished also by an abundance of Acila

(Truncacila) nehalemensis G. D. Hanna, which is rare 

in the lower member. The middle member of the 

Keasey consists of light- to medium-gray, relatively unstratified to massive, harsh, tuffaceous siltstone, which 

is associated with some hard calcareous beds and a few 

layers of ashy tuff. The most nearly continuous exposures of this member are along the Wolf Creek Highway in the vicinity of Sunset Tunnel, where the member 

is about 1,700 feet thick.

(3) The upper member of the Keasey formation, like 

the middle member, is highly tuffaceous, but it is somewhat more sandy and generally is thinner bedded 

than the middle member of the Keasey. It is one or 

two hundred feet thick. The fauna of the upper member is characterized especially by Lima, (Acesta) oregonensis Clark, but, among other elements, it contains a 

new species of TurcicuZa, which is quite distinct from 

T. cohimbiana Dall of the lower member of the formation. Other characteristic elements of the fauna from 

the upper part of the Keasey are Nemocardium lorenzanum (Arnold), Porterius gabbi (Dickerson), and 

Gyrineum jeffersonensis Durham. Porterius gdbbi 

was described from the type locality of the Gries Ranch 

formation in Washington and Gyrineum jeffersonensis 

from the lower part of the Quimper sandstone of Durham on the Olympic Peninsula of Washington, whero 

it occurs in strata containing a typical Gries Ranch 

fauna. The occurrence of these species in the Nehalem 

area suggests that the upper member of the Keasey 

formation may be the deeper water equivalent of the 

predominantly conglomeratic shallow-water Gries 

Ranch formation. This suggestion is strengthened by 

the fact that the fauna of the upper portion of the 

Quimper sandstone, which overlies beds containing a 

fauna having Gries Ranch affinities, is that of the Molopophorus gdb~bi zone of Durham. The fauna of this 

zone is the well-known Pittsburgh Bluff assemblage, 

occurring in the lower part of the Pittsburgh Bluff 

formation, the type section of which directly overlies 

Keasey strata in the Nehalem Basin area.

The crinoid remains here described occur in the upper 

half of the middle member of the Keasey formation. 

The tuffaceous material, which is dominant in the sediments, is mostly rather fine grained, but the random 

occurrence of ash "pebbles," one-q,uarter inch or more 

in diameter, suggests that the source of volcanic debris, 

which is so prominent a constituent of the Keasey sediments, was not far distant. No evidence of submarine 

volcanic activity has been seen at any outcrop of the 

Keasey formation, and thus it is reasonable to assume 

that the tuffaceous materials were derived from sources 

somewhere on the landward side of the Keasey shoreline, probably not more than a few miles away.

The invertebrate fauna associated with the crinoids
LOWER TERTIARY CRINOIDS FROM NORTHWESTERN OREGON 119

in upper part of the middle members of the Keasey 

formation consists mostly of mollusks, which are 

judged to have lived and been buried in relatively deep 

water. Among fossils collected with the crinoid remains at U. S. Geological Survey locality 15318 are the 

following species:

Invertebrates associated with crinoids in middle Keasey beds 

near Mist, Oreg.

Bolemya (Acharaan) willapaensis Weaver

Ennucula n. sp.

Acila (Truncacila) nehalemensis G. D. .Hanna

Nticulana icashingtoncnsis (Weaver), n. subsp.

Toldia (Portlandella) chehalisensis (Arnold)

Minormalletia n. sp.

Propeamussium n. sp.

Delectopecten n. sp.

Tellina n. sp.

Polinices n. sp.

Fulgurofusus n. sp.

"Cancellaria" n. sp.

Exilia lincolnensis Weaver

Scaphander stewarti Durham

Flabellum hertleini Durham

AGE OF THE KEASEY FORMATION

The Keasey formation was described by Schenck 

(1927, p. 457) as the Keasey shale and was considered

the lowest Oligocene exposed in the Columbia County 

area of Oregon. Recent correlations suggest its equivalence to Ludian and lower Tongrian strata of the standard European section (Weaver, et al., 1944, pi. 1), indicating that it is upper Eocene and lower Oligocene. 

Schenck and White (in Weaver, et cd., 1944, pp. 573- 

574) add: "We know of no convincing evidence to prove 

the precise correlation of any Tertiary formation in 

California with formations in Europe." In terms of 

the molluscan faunas, the Keasey fauna is clearly delimited from that of the upper Eocene Cowlitz formation and much more closely allied to that of the higher 

Oligocene horizons of Oregon and Washington. It is 

marked by the first appearance of a number of genera 

that are characteristic of the Oligecene and younger 

horizons and by a general absence of typical Eocene 

elements. The fauna of the lower zone witnesses the 

first appearance, on the west coast of North America 

at least, of such genera as Turcicula, Thyasira, Bruclarkia, and Cochlodesma, all of which range throughout 

the Oligocene section in this region.

The general Oligocene element in the fauna is well 

illustrated by the following table showing range of 

species known from the Keasey formation and adjacent 

horizons.

Stratigraphic distribution of invertebrates from the Keasey formation 

[X=speciflc identity, XU=upper faunal zone only, S=new subspecies in the Keasey fauna.)

Porterius gabbi (Dickerson) _ _ _ _"

Crenella porterensis Weaver. ______ _ __ ____

Nemocardium lorenzanum (Arnold)______ ____

Calyptraea diegoana (Conrad) _______ ___

Exilia lincolnensis Weaver. __ _ __ _ _

rJ PtfPMYi ^ -j/j/7 <-7j?*OT nffifn0'n 04*0 ^\A7'£*fi'\)r c-T*'^

Number of species or subspecies in common 

with Keasey fauna, ______

Cowlitz

(')

X

X

X

X

4

Keasey

S

X

xu

xu

X

X

xu

X

S

X

X

X

S

xu

S

X

S

X

S

X

X?

21

Gries 

Ranch

X

X

X

X

X

X

X

X

X

X

X

S?

X

S?

X

X

16

Pittsburgh 

Bluff

X

X

X

X

X

X

X

X

S?

X

X

X

X

13

Lincoln

X

X

X

X

X

X

X

X

X

X

10

Blakeley

X

X

X

X

4

Twin 

Rivers

X

1

' Weaver's reference (1943, pp. 184, 636) of this species to the Cowlitz formation is clearly a lapsus, since he correctly states that it was described from the Qries Ranch, 

then fails to list it from that horizon.
120 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1950-51

The implied indication that the Keasey fauna is no 

more closely related to the fauna of the Cowlitz formation than it is to that of the upper Oligocene Blakeley 

formation of Weaver (Echinophoria rex zone) is a 

reflection of the extent to which new Oligocene elements 

enter the fauna of the Keasey formation. The only 

species the Keasey and Cowlitz faunas have in common 

are forms that range throughout middle and upper 

Eocene on the west coast, and two of the three that are 

so found range on up into the middle Oligocene. All 

three forms, furthermore, are relatively generalized 

types without many characteristics suitable for close 

specific discrimination.

As noted by Schenck and White (loc. cit.), there is 

no evidence suggesting a precise correlation of the 

Keasey formation with the standard European section; 

nevertheless, in terms of the fossil molluscan faunas 

of the west coast, the Keasey is clearly much more of 

Oligocene aspect and relationship than Eocene.

OUTCROPS OF THE KEASEY FORMATION FROM WHICH 

CRINOID REMAINS HAVE BEEN COLLECTED

U. S. Geol. Survey loc. 15268: Large cut at south end of high 

overpass of United Railroad crossing Oregon Highway 47 

(Buxton-Vernonia highway) : 6,400 feet west of grid 815,000 

and 11,300 feet south of grid 2,645,000, Verononia quadrangle, U. S. Army Engineers, 1943 edition.

U. S. Geol. Survey loc. 15282: Prominent road cuts on opposite 

sides of the Wolf Creek Highway (Oregon Highway 2) 0.90 

to 1.0 mile northwest of western end of the Sunset Tunnel, 

Timber quadrangle, U. S. Army Engineers, 1941 edition.

U. S. Geol. Survey loc. 15985: On coast about 1.25 miles (air 

line) north of Yachats, Lincoln County, Oregon. South 

64°30" West of fire lookout tower on Blodgett Peak, Waldport quadrangle, U. S. Army Engineers.

U. S. Geol. Survey loc. 15314: Cut in low banks on south side of 

abandoned logging railroad that paralleled Crooked Creek. 

Outcrop is at west end of "Ross Siding," 2.55 miles (direct) 

west-northwest of Pittsburgh Bluff; 3,000 feet west of grid 

815,000, on the line of grid 2,660,000, Verononia quadrangle, 

U. S. Army Engineers, 1943 edition.

U. S. Geol. Survey loc. 15318 (also Univ. California loc. A5018) : 

Prominent bluff on west side of Nehalem River, immediately 

south of bridge for small side road and approximately 

3,500 feet south of junction of Oregon State Highways 47 

and 202 at Mist, Oreg.

U. S. Geol. Survey loc. 15508: Prominent cut on north side of 

horseshoe bend on United Railroad with high overpass over 

Oregon Highway 47. Locality is in second cut beyond the 

north end of trestle. (Loc. 15268 is first cut at south end 

of same trestle.)

DESCRIPTION OF CRINOIDS 

MATERIAL AVAILABLE FOR STUDY

Initially available crinoid specimens collected from 

the Keasey formation in northwestern Oregon consisted 

of the remarkable crown that is here designated as the 

holotype of Isocrinus oregonensis Moore and Vokes, n. 

sp., collected by Messrs. Warren and Grivetti from the 

locality on the Nehalem River near Mist, Oreg.

(U.S.G.S. locality 15318), and a few fragments of 

columnals from this and other localities in the area. 

Associated with several of the stem segments were portions of attached cirri. Most of these stems consist of 

fairly well preserved calcite, free of matrix or partly 

imbedded in the rock. The latter specimens proved 

very difficult to prepare because the matrix is so much 

harder than the calcite of the fossils. Several specimens are external molds of individual columnals and 

segments of the stem consisting of articulated series of 

columnals and of cirri. The molds had been formed 

by weathering and solution of the calcite so as to leave 

nearly perfect impressions of the form of the fossil in 

the essentially noncalcareous matrix. Such specimens 

clearly show the crenellae of articular surfaces of columnals and features of the lateral surfaces of stem 

segments, including especially ,the pattern made by 

edges of crenellae between individual columnals and 

sockets for attachment of cirri.

As previously noted, during the field season of 1946 

Vokes and Snavely visited the locality from whkh 

the holotype of Isocrinus oregonensis had been ol - 

tained and were successful in collecting from the thi i 

crinoid-bearing zone of the Keasey formation about 50 

pounds of rock. When this material was unpacked by 

Moore, he was much disappointed at its extremely unpromising nature. Although he did not expect duplication of such finds as the exceptional crown first 

collected by Warren and Grivetti, he hoped that additional search at the fossil locality might yield fairly 

well-preserved crinoid arms, stems, and possibly one 

or two dorsal cups that would aid importantly in understanding features of the specimens first studied. Stem 

and arm fragments were, in fact, found to be fairly 

common in the material shipped in the matrix, but the 

more or less rotted calcite of most fossils had been 

broken through so as to reveal only the gross pattern 

of crinoid structures. The presence of abundant 

crinoidal material along some bedding planes was indicated by cross sections of fragments visible on sides 

of the blocks. Efforts to break the rocks along such 

bedding planes, however, so as to expose crinoids were 

not successful, because fractures carefully made along 

chosen bedding planes broke through the fossils rather 

than between the crinoids and adhering matrix. Considerable time was spent on the most promising specimens in efforts to remove the matrix so as to expose 

crinoid remains with unmarred surface. Most of this 

work was done under a binocular microscope so as to 

watch the preparation closely. Power tools, both 

abrasion- and percussion-types, were useful for preliminary stages of cutting, but, because of the softness of 

the calcite, these proved unsuitable for work close to 

the specimen. Very sharp chisel-edged needles, operated by hand, did good work, but progress was pain-
LOWER TERTIARY CRINOIDS FROM NORTHWESTERN OREGON 121

fully slow, and hardness of the matrix as compared 

with the fossils made it almost impossible, even with 

greatest care, to expose crinoid remains without damaging their surface.

Decision was made at length to test removal of the 

mostly soft, partly decomposed calcite by etching fragments of crinoid-bearing rock in weak acid. It was 

found that the tuffaceous material of the matrix is not 

at all affected by the acid or only imperceptibly etched, 

whereas the calcite of the crinoids was quickly eaten 

away. As a result of this treatment, beautifully sharp 

external molds were obtained that permitted definite 

identification of many structural features not otherwise 

observable. A disadvantage, which shortly became evident in this method of preparation, however, was the 

almost uncontrollable tendency of the rock when wet 

in acid to break apart unpredictably. This fragmentation evidently is induced by swelling of disseminated 

bentonitic material in the rock. By treating surfaces 

with an acid-resistant plastic, such as ambroid or alvar, 

not too much thinned, it was possible to hold most 

specimens together or to cement in position pieces of 

the rock that broke loose.

This method of treatment was ultimately applied 

to nearly all of the shipment of bulk rock material 

from the crinoid locality, and it yielded innumerable 

specimens of parts of the stem, arms, and pinnules. 

Also, it led to discovery of several additional crowns 

of various size and completeness—all this from material 

that initially seemed to be almost valueless. The prepared fossils are extremely fragile, for efforts to harden 

the molds by soaking in a thin solution of plastic generally produce further decrepitation.

After completion of a report, based on specimens collected by U. S. Geological Survey parties in Oregon, 

eight pieces of crinoid-bearing rock fragments from the 

Keasey formation at the Mist locality (U. S. Geological 

Survey loc. 15318) were borrowed from the Museum of 

Palaeontology, University of California, at Berkeley. 

The specimens bear University of California locality 

number A5018 and for purpose of individual identification have been lettered A to H, respectively. Incomplete crowns occur on specimens A, B, and C 

(two crowns on C being designated as Cl and C2); the 

other specimens (D to H) bear only stem and arm fragments. The calcite of the fossils on all specimens is 

firm and the rock in which they are embedded is very 

hard, unweathered tuffaceous siltstone. After preparation, the fossils stand out in relief. Some have 

about the same hue as the light greenish-gray matrix, 

but others are stained pink or brown, and some show a 

very dark greenish-brown color, which makes them 

strikingly conspicuous. At first glance, these last resemble various Ordovician and Mississippian crinoids, 

such as those from the Trenton group of New York

and the Crawfordsville beds of Indiana. The four 

crowns in the University of California collection are 

of Isocrinus oregoriensis, and are especially valuable in 

clearly showing characters of the dorsal cup. Among 

numerous stem fragments, both /. oregonensis and /. 

nehalemensis are recognized, the former being much the 

most common. Specimen C carries three sections of 

cirrus-bearing stems 32, 35, and 55 mm long.

Altogether, the specimens studied in preparing this 

report consist in only very minor degree of completely 

dissociated crinoid fragments. Most of them are 

segments of stem and cirri made up of many adhering 

segments or arm fragments in which many brachials 

are arranged in unbroken series, generally with pinnules in attached position. Elements of the crowns 

are mostly not broken apart. Uncompressed or with 

only little flattening, they lie in positions in which the 

animals were buried. The more or less accidental way 

in which the crowns are exposed in preparation and 

the difficulty of exploring structures by removing 

matrix where desired are the main handicaps in working with these fossils.

SUPRAFAMILIAL PLACEMENT OF THE OREGON 

CRINOIDS

The fossil crinoids from lower Tertiary deposits of 

Oregon described in this report give complete enough 

morphological information to warrant using them as 

basis for a review of questions of major taxonomic divisions among post-Paleozoic crinoids. The Keasey 

crinoids clearly belong to the group called pentacrinoids. These are a stock of relatively large-crowned, 

pentagonal-stemmed, cirriferous crinoids which have 

special importance by reason of their abundance, cosmopolitan distribution, longevity, and (not least) inclusion among them of the ancestors of the Comatulida—the dominant group among modern crinoids. 

They are far removed from other stalked and unstalked 

crinoids of Mesozoic and Cenozoic age, such as the 

eugeniacrinids, bourgueticrinids, thiolliericrinids, 

comatulids, and others. Suprafamilial allocation of 

the Oregon crinoids may be indicated in terms of assemblages of decreasing magnitude, as Phylum Echinodermata, Class Crinoidea, Subclass Articulata, and 

Order Pentacrinoidea.

FAMILY ISOCRINIDAE GISLEN, 1924

This family comprises Mesozoic and Cenozoic genera, 

including among forms known as fossils, Isocrmus, 

Cainocrinm, Ba2anocrinus^ and Austinocrinus^ and living genera of stalked crinoids, such as Metacrinus, /Saracrinus, Cenocrinus, Teliocrinus, Endoxocrinus, Diplocrinus, Annacrinm, Neocrinus, and HypcHocrinus. The 

assemblage was differentiated independently by Matsumoto (1929, p. 31) under the same family name, seemingly without knowledge of Gislen's publication.
122 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1950-51

In genera assigned to the Isocrinidae, the inf rabasals 

are hidden or they may have vanished; the basals are 

small and generally, in external view, not in lateral 

contact with one another; and the radials are normal, 

without downward pointing processes. Branching of 

the rays is isotomous, bifurcation occurring once or as 

many as four or five times. Pinnulation is complete, 

except on proximal brachials. The tegmen is small. 

Columnals belonging to isocrinid genera are stellate, 

pentagonal, quinquelobate, or circular in section, with 

articular facets marked by short to moderately long 

crenellae at borders of five variously shaped floor areas. 

The maximum number of internodals (mostly 5 to 15) 

is attained not far below the dorsal cup. Cirri of subcircular cross section are attached to nodals in whorls 

of five, or with alternating position on successive nodals, they may be reduced to three, two, or one.

The range of the Isocrinidae is from Triassic to 

Recent.

The Oregon material confirms Gislen's (1924) view 

that Pentacrinus and Isocrinus stand well apart, belonging to different families, Pentacrinidae and Isocrinidae. The former comprises Pentacrinus and Seirocrinus, and the latter includes (among fossil forms) 

Isocrinus, Balanocrinus, and Austinocrinus (SievertsDoreck, 1943). The Oregon crinoids help fill a great 

gap in paleontological knowledge of Tertiary crinoids 

in general and Isocrinidae in particular. The search 

for relatives of the Oregon forms has been hampered 

by the fact that many Tertiary Isocrinidae are poorly 

known, insufficiently described and illustrated, and 

ranged under Pentacrinus, to which genus they surely 

do not belong; they may represent Isocrinus, Balanocrinus, or the predecessor of a Recent genus.

GENUS ISOCRINUS VON MEYER, 1837 

Genotype: Isocrinus pendulus von Meyer, 1837 (by monotypy).

Isocrinites von Meyer (as Isocrinites pendulus von Meyer),

L'lnstitut, (December 30, 1835), 1836, p. 435 (nomen

nudum). 

Isocrinus L. Agassiz (based on Isocrinites pendulus von Meyer),

Soc. Sci. Nat. Neuehatel Mem., vol. 1, p. 195, 1836 (invalid

because based on nomen nudum). 

Isocrinus von Meyer (as Isocrinus pendulus von Meyer, n. sp.),

Mus. Senckenberg, vol. 2, p. 260, pi. 16, figs. 1-5, 1837.

The crinoid generally known as Isocrinus and attributed to Louis Agassiz (1836) cannot be recognized 

by this name, author, and date, inasmuch as no described 

species was then attributable to it. Clark (1908, p. 

526) cites von Meyer (1836) as originator of the generic name Isocrinites (based on Isocrinites pendulus 

nomen nudum), but this also surely is erroneous. The 

crinoid named and described by von Meyer in 1837 as 

Isocrinus pendulus must be taken as the basis both of 

the specific and the generic names, for prior to that 

time it had no status in scientific literature. Accordingly, the generic name here recognized is Isocrinus, 

and von Meyer is regarded as the nomenclator.

The Oregon crinoids described in this report are assigned to Isocrinus because of (1) the nature of their 

columnals, including stellate shape in cross section, 

petaloid pattern of the articular facets, number of internodals, and presence of five elliptical cirrus sockets on 

nodals, and (2) structure of the rays, including the 

isotomous mode of branching, union of the two primibrachs of each ray by synarthry, and the nature of 

pinnulation.

Isocrinus is the most important genus of the Pentacrinoidea. Although Pentacrinus is very commonly 

cited in literature, Bather (1898) showed that many 

fossil species assigned to Pentacrinus really belong to 

Isocrinus. It is appropriate to define characters which 

distinguish Isocrinus.

CHARACTERS OF ISOCRINUS

Isocrinus is a medium-sized to large pentacrinoid that 

has a long cirrus-bearing stem of pentagonal or stellate 

cross section, diminutive dorsal cup, and generally long 

pinnulate arms, which bifurcate isotomously. The 

crown typically flares upward so as to attain greatest 

width at or near the arm trips. Distinguishing features are found in structures and ornament of the stem, 

dorsal cup, and arms, including especially the nature 

of branching in the rays, articulation of brachials, and 

placement of proximal pinnules. The genus has a 

greater stratigraphic range than that of any other 

articulate crinoid, for it is recorded from Lower Triassic to Recent.

Column.—The stem is composed of more or less evensized pentagonal or stellate columnals having diameter 

several times greater than their thickness. They are 

divisible into nodals, which bear cirri, and internodals, 

which lack cirri. The contact between columnals is 

marked by crenulate sutures, except on the distal side 

of nodals, where a straight suture occurs. The articular surfaces are characterized by strongly petaloid floor 

areas, bordered by short crenellae, but the distal face 

of nodals and the apposed face of hypozygal internodals are nearly smooth. Radial pores may be present 

at re-entrant angles of the stem between internodals, 

at least in proximal parts of the column. The cirri 

generally occur in whorls of five. As in other genera 

of the Isocrinidae, the sockets for cirrus attachment are 

subcircular to elliptical in outline.

Dorsal cup.—The dorsal cup of Isocrinus is very inconspicuous. It is shallow basin-shaped and not much 

greater in diameter than the stem—almost invariably 

less than twice the stem diameter. Infrabasal plates, 

which are recorded in some species, are reduced to 

diminutive size and entirely concealed by the proximal 

columnal. Basals are externally visible as widely sep-
LOWER TERTIARY CRINOIDS FROM NORTHWESTERN OREGON 123

arated small projections of the cup above angles of the 

stem, but actually they adjoin beneath overlapping 

parts of the radials and the proximal columnal. The 

radials are relatively thick and extend outward in 

nearly horizontal or slightly up-flaring direction; their 

proximal portions may form part of a basal concavity 

of the cup. The articular facets are equal in width to 

the radials.

Arms.—Two primibrachs occur in each ray of Isocrinus, the second being an axilliary that supports 

equal-sized branches. Two or more bifurcations occur 

in each ray. Articulation between the two primibrachs 

(and generally between the first two secundibrachs) is 

synarthrial, but between the primaxil and first secundibrach of each branch articulation is muscular. Union 

between secundibrachs and higher series of brachials 

normally is by muscular articulation, but some pairs of 

brachials are joined by syzygy. Generally, as first 

noted by Biese (1930, p. 715), the third and fourth 

secundibrachs are syzygially united; study of the Oregon specimens indicates that the second and third tertibrachs and quartibrachs are likewise connected by 

syzygies. The most proximal pinnules of each ray 

normally appear on the second secundibrach, as in 

most articulate crinoids. They are directed toward the 

outer sides of the ray. Pinnules are moderately stout 

and long, the proximal pinnular being typically much 

shorter than others.

COMPARISON WITH RELATED GENERA

Some authors have classed Isocrinus as a synonym of 

Pentacrinus Blumenbach, of Jurassic age, despite the 

fact that these genera, as now understood, stand rather 

widely apart, being assigned to different families. 

Bather (1898) and Gislen (1924) have pointed out distinguishing features, among which the most readily 

observed is the rhombic cross section of the cirri of 

Pentacrinus, as contrasted to the elliptical or subcircular cross section of cirri belonging to Isocrinus. Also, 

the heterotomous bifurcations of the rays and downward projecting prominences on radials of Pentacrinus 

differ from the isotomous branching and smoothly 

rounded radials of Isocrinus.

Cainocrinus Forbes (1852, p. 33, figs. 1-5) was described on the basis of a small dorsal cup with attached 

portion of stem and some isolated fragments of columns 

from the London clay (Eocene) of southern England. 

It is an isocrinid characterized by a moderately elevated 

bowl-shaped cup with upflaring radials and externally 

visible contacts between the gently curved basals. The 

column is pentalobate, somewhat like that of Isocrinus 

and Balanocrinus; it has widely spaced nodals which 

bear a whorl of five cirri with subcircular cross section. 

The nature of articular facets is not described or figured, 

and accordingly, relationships to Isocrinus are indeterminate. Cainocrinus occurs in rocks of nearly the 

same age as deposits containing the Oregon crinoids, but 

the genus obviously differs from Isocrinus in features 

of the dorsal cup.

Balanocrinus de Loriol, which ranges from the 

Middle Triassic to the Miocene, was originally described as a subgenus of Isocrinus, distinguished solely 

on the basis of characters of columnals. Proximal 

parts of the stem of Balanocrinus may be quinquelobate 

or pentagonal in section, and articular surfaces of columnals may bear a strongly petaloid pattern, indicating similarity to Isocrinus, its probable ancestor. Typical Balanocrinus columnals, however, have a rounded 

outline, crenellae restricted mainly to the -periphery, 

and obtusely triangular floors separated by reduced 

crenellae, line of granules, or radial ridges that define 

a star-shaped rosette centered on the minute round 

lumen. Nodals bear one to three cirrus attachment 

sockets, rather than five, as normally in Isocrinus, and 

the reduced number of cirri seen in Balanocrinus accompanies an alternation in arrangement of the cirri on 

successive nodals. Discovery of a crown belonging to 

Balanocrinus subbasaltiformis (Sowerby) in Eocene 

(Ypresian) beds of southeastern England has permitted the observation (Sieverts-Doreck, 1943, p. 152) 

that Balanocrinus resembles Isocrinus in having only 

two primibrachs, but they are joined by synostosis instead of synarthry. Also, unlike Isocrinus, the first 

and second secundibrachs are united by synostosis; 

neither synarthrial articulations nor syzygies between 

any brachials are recognized. The dorsal cup of B. 

siibbasaltiformis is nearly identical to that of the Oregon 

species of Isocrinus described in this report.

Another genus of Isocrinidae is Austinocrinus de 

Loriol, which is distinguished on characters of columnals, other parts being unknown. According to 

Springer (1913, p. 233), Austinocrinus corresponds to 

Isocrinus except in having finer crenellae along borders 

of the petaloid floor areas of the columnal facets. Actually, Austinocrinus resembles Balanocrinus more 

closely than Isocrinus, especially in the pattern of articular surfaces of the columnals, rounded cross section 

of the stem, and reduced number of cirri attached to 

nodals. As in many species of Balanocrinus, the cirri 

may be reduced and disposed in alternating position on 

successive nodals. Austinocrinus is widely distributed 

in Upper Cretaceous rocks of both hemispheres but is 

unknown in other systems.

Among living Isocrinidae are two genera that correspond to the Oregon species of Isocrinus in characters of the column and dorsal cup, and in having only 

two primibrachs which are joined by synarthry. They 

are Neocrinus Wyville Thomson, 1864, and Hypalocrinus A. H. Clark, 1908. These genera, however, are 

characterized by strongly interlocking immovable ar-
124 SHORTER CONTRIBUTIONS TO GENERAL GElOLOGY, 1950-51

ticulations between certain brachials, of a sort quite foreign to typical Isocrinus and not observed in the Oregon 

crinoids from the Keasey formation. Thus, Neocrinus 

and Hypalocrinus evidently represent a separate tribe 

of Isocrinidae.

Occurrence of a syzygial union between first and 

second .primibrachs in Metacrinus P. H. Carpenter, 

Teliocrinus Doderlein, Genocrinus Wyville Thomson, 

Annacrinus A. H. Clark, Endosoocrinus A. H. Clark, 

and Diplocrinus Doderlein distinguishes these genera 

from Isocrinus (Doderlein, 1912, p. 22; Clark, 1923). 

There are other differences, such as greater length of 

the primibrach series (normally 4 to 8 brachials) in 

Metacrinus. Saracrinus A. H. Clark also differs from 

Isocrinus in having four primibrachs in each ray.

To summarize, Isocrinus is most closely related to 

Balanocrinus, among fossil crinoids, and to Hypalocrinus and Neocrinus among living forms. It is distinguished from Balanocrinus especially by characters 

of the columnals and the articulation between brachials. 

Hypalocrinus and Neocrinus are distinguished by the 

interlocked type of union of some of their brachials.

ISOCRINTTS OREGONENSIS MOOBE AND YOKES, N. SP.

Pis. 14-18; pi. 19, figs. 2-5; pi. 20, fig. 3; pi. 22, fig. 3; pi. 23, 

figs. 1-3, 5-6, 8-10; pi. 24; text figs. 29-35, 36A, 36D-E, 39D.

SUMMARY OF DESCRIPTION

Crown unusually tall, expanding upward, consisting 

of small, discoid dorsal cup and rays that bifurcate isotomously three times, so as to terminate in as many as 

40 long, slender arms.

Dorsal cup subpentagonal in outline, having approximately twice the diameter of the column. Infrabasals 

not observed. Basals small, bulbous, externally visible 

only above angles of stem, but adjoining laterally beneath the proximal columnal. Eadials stout, strongly 

curved in longitudinal profile, directed horizontally, 

forming lower side walls and floor of cup. Radial 

facets wide, with broad area for dorsal ligament.

Primibrachs two, united by synarthry, laterally adjoined to neighboring primibrachs in relatively immovable manner. Secundibrachs 6 to 7, with a syzygy 

normally uniting IIBr3+4 . Tertibrachs 9 to 16, with 

syzygial union between IIIBr2+3 . Quartibrachs more 

than 60 (at least 88 in some arms), with syzygy between 

IVB2+3 and sporadically between some higher pairs. 

Pinnules relatively long and stout; proximal pinnule 

shorter than others. The most proximal pinnule occurs on IIBr2 , directed toward outer side of the ray.

Column long, stellate in section, nearly equal in width 

throughout. Columnals relatively thin, nearly uniform in diameter, nodals only a little larger than internodals, which normally number 7 in each series, except 

near the dorsal cup. Sides of columnals smooth, 

slightly carinate. Joint faces marked by long narrow

floors and short crenellae. Nodals bear elliptical sockets for attachment of 5 long, stout cirri, which are directed upward in their proximal region. The distal 

articular face of nodals is nearly smooth, denoting 

synostosial union with the adjoining internodal, which 

also has a smooth facet.

DESCRIPTION OF SPECIMENS 

HOLOTYPE

The superb fossil crinoid (U.S.N.M. 560790D 1 ), 

which is the holotype of Isocrinus oregonensis, consists 

of a crown and attached proximal portion of the stem 

from the outcrop of the Keasey formation at U.S.G.S. 

loc. 15318. It occupies most of one surface of a slab 

measuring roughly 8 by 10 inches (pi. 14, text fig. 29). 

The arms spread out radially from the dorsal cup, like 

spokes of a wheel, so as to reveal portions of almost 

every arm. Most of the arms are bordered on one or 

both sides by outstretched pinnules. It is as though 

the specimen had been laid out by a botanist for pressing in his herbarium. Maximum dimension across the 

outstretched arms is 210 mm. The diameter of the 

dorsal cup is barely 10 mm. An outstanding feature of 

the holotype specimen is the remarkable length of the 

unbranched arms, forming terminal portions of the 

rays. Several of these are at least 90 mm in length. 

The height of the crown, as represented by this specimen, may be given as approximately 125 mm.

The specimen is mostly an external mold, for the 

original calcite of the dorsal cup, arms, and column is 

gone. The somewhat discolored and decomposed calcite of some pinnules remains in place. Although the 

holotype of Isocrinus oregonensis shows general structure of a nearly complete crown, the nature of articulations between ray plates is generally obscure or lacking. 

In this respect the holotype is decidedly inferior to most 

of the paratype specimens prepared by etching with 

acid.

It has not been possible to determine orientation of 

the holotype specimen—that is, to ascertain which is the 

anterior ray and where the posterior interradius belongs. Accordingly, in order to facilitate reference to 

individual parts of the specimen, the rays are numbered 

in arbitrary manner (fig. 29) starting at the left and 

proceeding in clockwise manner around the spread-out 

arms (the terminal parts of each ray being lettered 

a to A, inclusive).

Enlargements of portions of the holotype specimen 

are illustrated in plates 15-17.

PARATYPES

Ten paratype specimens, all but one consisting of 

more or less complete crowns, are illustrated or used in

1 All catalogue numbers cited are those of the United States National 

Museum unless stated otherwise.
LOWER TERTIARY CRINOIDS FROM NORTHWESTERN OREGON 125

preparation of diagrams in this paper. Stem fragments, classed as paratypes, also are figured. Much 

additional paratype material is not illustrated. Most 

of the figured crowns are acid-etched preparations of 

rock collected from the crinoid bed at the Mist, Oregon 

locality (U.S.G.S. 15318) in 1946. Although none of 

the paratypes is comparable in perfection and beauty

to this crown. As clearly shown in the figures (pi. 

18; text fig. 31), the proximal part of the column is 

strongly stelliform in outline. The proximal columnals are centrally placed at the base of the cup. Seemingly, only a small part of the normally very long 

quartibrach portion of the arms is preserved in this 

specimen. It is probable that these outer parts of the

2c2d

2e 2f 2g 2h

3e

3f 

3g

3h

5f

50 100mm

FIQUKE 29.—Holotype of Isocrinus oregonensis. The drawing corresponds to the photographic illustration reproduced in plate 14, with enlargements 

as given in plates 15-17. For purpose of identifying parts of the crown, arms are designated by numbers to denote rays, and letters to denote 

individual arms; the assignment of these designations proceeds clockwise, beginning at the left. Thus, the eight^arms of ray number 2 

(enlarged in plate 16) are indicated by 2a to 2h.

to the holotype, they have thrown much light on the 

structure of the dorsal cup, arms, and stem, and they 

have been particularly useful in indicating the nature 

of articulations between the plates of the rays.

Paratype A (U.S.N.M. 560791A) is a crown viewed 

from the ventral side, the arms being spread out in 

radial manner around the cup. The greatest dimension 

across the exposed arms is about 110 mm. At one side 

are portions of the stem and cirri that evidently belong

arms were present originally, and they may be represented in some of the fragmentary material that became 

separated during preparation. The very robust nature 

of proximal pinnules belonging to some of the rays is 

well shown.

Paratype B (U.S.N.M. 560791B) is a fairly robust, 

well-preserved crown in which the arms of the lower 

part of the crown are closely crowded together. The 

distal part of the arms is mostly missing. The nature
126 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1950-51

FIGURE 30.—Paratype A of Isocrinus oregonensis. The drawing corresponds to the photographic illustration reproduced in plate 18 

The structure of arms lettered A-H is represented in text figure 31. X, Y show side views of nodal columnals and part of attached 

cirrus, probably belonging to paratype A.

IBrr

R 1

EXPLANATION

Pinnule \^* 

Axillary plate 

Syzygy ~ 

Synarthry I

IIBrr IIIBrr IVBrr

\ 1.9^.4

A

B

1-2-3-4-5 6

X* .l-2-3;4-5;6-7-8-9-10-lM2-13-14-15-16 C

'^^ ^-v^>^*^* ^' ^- ^«

^l.2:3*4-5r6-7'8'9': 10-ll*12-13'-U-15'-16 D

.l-2-3'4-5-6-7-8-9-10-ll-12-13-14-15-16-17 E

,'',-*

1-2-3-4-5-6 17

1-2-3-4-5-6-7-8-9-10

w 1- 2-3 4 :5 7-8: 910; ll 12 • 13- 14; 15 16

\

>'^ .'"" X 

x** x -' ^-' ^* x'' >!'2-3^-4 ^-6 - 

l-2f'4-5'6^7'8-9'lO-ll-12v ^3> ^^ "% 

^ X. ^* ^ X X. .\1-2-s'4-.V6- M-2-3'4- 5'6--- -

G 

H

FIGURE 31.—Ray structure of paratype A of Isocrinus oregonensis. The arms lettered A-H are indicated in text figure 30 and illustrated in plate 18. Syzygial articulations 

are definitely recognized where indicated; they are very constant between second and third plates of the tertibrach and quartibrach series. Inferred location of pinnules 

is indicated by broken lines, and observed pinnules (or pinnule sockets) are indicated by solid lines. The proximal pinnule on the branch bearing arms A-D is abnormal 

in that it seemingly occurs on IIBn instead of on IIBn.
LOWER TERTIARY CRINOIDS FROM NORTHWESTERN OREGON 127

of articulations between the radials and first primibraehs and between plates of the rays is well shown, 

and most of the structure for at least four of the rays 

can be determined (text fig. 32). The arms are too 

closely appressed to show well the arrangement of pinnules, except in one of the arms that is somewhat separated from the remainder of the crown. This arm 

bears unusually coarse, long pinnules. An intact part 

of the stem, which evidently belongs to this crown, lies 

close to its base but disposed in a transverse manner. 

It comprises seven groups of nodal and internodal

columnals, several of the nodals bearing cirri in attached 

position. This specimen measures about 100 mm across 

its largest part.

Paratype D (U.S.N.M. 560791D) consists of a group 

of arms and the lower part of a crown, the total length 

of exposed arms being about 90 mm (pi. 19, fig. 4). 

Fairly complete regularly spaced pinnules appear at 

the side of the arms.

Paratype E (U.S.N.M. 560791E) is a crown spread 

out so as to show all of the rays radiating from the 

centrally placed dorsal cup. The specimen measures

IIlBrr'

IBrr/

EXPLANATION 

Synarthry MM 

Syzygial articulation [«-| 

Muscular articulation

0 10 20 30mm

FIGURE 32.—Paratype B of Isocrinus oregonensis and diagram of ray structure. Subdivisions of the rays are correspondingly lettered on the drawing of this paratype and 

the diagram showing structure. Syzygies are irregular in the secundibrach series of this specimen in that some branches lack them, others are normal in showing syzygial 

union of IIBrs+i. With one exception, IIIBra+j and IVBrz+j are joined by syzygy. Union between IBn+s is synarthrial.
128 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1950-51

about 150 mm across its widest part (pi. 19, figs. 2, 5). 

Several very robust pinnules belonging to lower parts 

of the ray are well shown.

Paratype L (U.S.N.M. 560791L) clearly shows the 

arrangement of plates of the dorsal cup, and structure 

of the lower parts of the crown (pi. 20, fig. 3).

Several lots of stem fragments and isolated columnals are included among paratypes of Isocrinus oregonensis, illustrated specimens appearing in plate 23, 

figs. 1-3, 5-6, 8-10 (U.S.N.M. 560903A-C).

Paratype U.C.M.P. (University of California Museum of Palaeontology) A5018A is a completely exposed dorsal cup with remnants of proximal columnals 

attached and, spread out around the cup, arms representing all of the rays. The structure of the lower 

part of the arms in some of the rays is determinable 

but only in one ray is all of the tertibrach series visible, 

and pinnules are not very well shown. This specimen 

is illustrated in Plate 24, figure 4 and text figure 35E. 

Measurement across the crown in one direction is 100 

mm and at right angles about 60 mm; the evenly pentagonal dorsal cup has a diameter of 10 mm and height 

of 4 mm.

Paratype U.C.M.P. A5018B is a crown having a 

maximum length of some of the arms of 60 mm. (pi. 

24, fig. 1). The primibrach series of all rays are preserved, but secundibrach and tertibrach series can be 

seen in only three of the rays. Although a small part 

of the dorsal cup is lost, some of the radials and basals 

are complete and all plates of the cup are represented. 

A couple of the strongly stellate proximal columnals 

are joined to the "base of the cup (pi. 24, fig. 3). The 

fracture which obliquely intersects one side of the cup 

(lower part of text figure 35Z>) reveals the suture between two basals toward the edge of the stem, where 

normally this suture is covered by the proximal extremity of a radial plate. This dorsal cup, which lies on 

the edge of a rock fragment 100 mm long and 45 mm 

wide is completely visible from the base and on all 

sides. It has a diameter of 10 mm and a height of 

4 mm.

Paratypes U.C.M.P. A5018C1 and A5018C2 are on 

a block of rock 220 mm long and 120 mm wide. One 

of the surfaces of this block also shows three relatively 

long articulated pieces of stem (to 60 mm) and smaller 

sections of joined columnals, all belonging to Isocrinus 

oregonensis (Paratype U.C.M.P. A5018C3, pi. 22, fig. 

3). One of the stems has many attached cirri, regularly spaced in whorls surrounding the column. Paratype U.C.M.P. A5018C1 is a good specimen that lies on 

its side, one half projecting above the surface of the 

block and the other half buried in hard matrix. Preparation of the dorsal cup has revealed most of it, only 

one radial being entirely covered, and joined to the base 

of the cup are several columnals. The highest part of

the arms in any of the preserved rays belongs to the 

tertibrach series. The crown is 40 mm wide and 35 

mm high, with the dorsal cup 10 mm across and 4 mm 

high. Paratype U.C.M.P. A5018C2 is unimportant. 

It is an incompletely exposed basal part of a crown 

about 25 mm high and 18 mm wide. The dorsal cup 

probably is present, buried in the matrix, because the 

first primibrachs are visible on two of the sides. No 

effort to expose the base of the crown has been made. 

Paratype U.C.M.P. A5018C1 is illustrated in Plate 24, 

figure 2, and in text figure 35J., B.

Of other University of California paratypes, only a 

stem fragment on U. C. M. P. A5018H is here described 

and figured (text figs. 35 F-I). It consists of the 

epizygal cirrus-bearing nodal and seven proximally 

succeeding internodals which normally remain joined 

together. The distal articulating surface of the epizygals is nearly smooth, so that rupture of the stem at 

this point is easy. Cirrals are attached to this stem 

fragment on all sides of the nodal. The figured fragment is 6.8 mm long and the stem is 6 mm in diameter.

DORSAL CUP

Identifiable plates of the dorsal cup consist of radials 

and basals, which are joined to form a relatively stout 

structure having a width slightly less than twice the 

diameter of the stem attachment and height nearly onehalf of the width. The part of the base of the cup 

which is covered by the proximal columnal and composed of proximal surfaces of the radials is a flat horizontal plane. The basals project below this plane, 

however. Total height of the cup is most readily and 

accurately measured at the angles occupied by the bulging basals going upward from their lower extremity 

to the summit of an interradial suture.

Infrabasals occur in other species of Isocrinus but 

are not observable in any of the Oregon specimens.

The basals are small, moderately to strongly bulbous 

plates having a rhomboidal outline as seen in oblique 

view from below. They rejoin the outer angles of the 

column, and on some specimens they protrude like 

short blunt spines. The bulbous basals project downward rather than sideward, and accordingly they tend 

to produce a concave outline of the cup base. They 

are not laterally in contact externally but are separated 

by proximal extensions of the radials, which reach to 

the base of re-entrant angles of the proximal columnals. 

The proximal parts of the basals extend beneath the 

stemward tips of the radials, however, so as to join one 

another laterally, not only in the area covered by the 

stem but outside of this (text fig. 35Z>, lower part).

The circlet of radials comprises most of the cup; 

these plates are somewhat wider than long, laterally in 

contact with one another on the exposed side of the cup, 

and very strongly convex in longitudinal profile.
LOWER TERTIARY CRINOIDS FROM NORTHWESTERN OREGON 129

•40

EXPLANATION 

Syzygy

-^ Synarthry

. Muscular

articulation

^^ Axillary

^ Pinnule

R Radial

.13-14 P-——-

FIGURE 33.—Ray structure of paratype L of Isocrinus oregonensis. This specimen is distinguished by unusual variability in location of

syzygies in the secundibrach series.

Sutures between the radial plates are well defined but 

not impressed. The entire distal margin is occupied 

by an articular facet for support of the base of a ray. 

The margin of the facet appears straight in slightly upward oblique side view of the cup but is actually curved, 

for the very broad outer ligament area of the facet 

reaches downward in the midportion of the radials. 

Characters of the articular surface of the radials are 

not shown by the holotype but are partly discernible on 

some of the paratypes (text fig. 35 J.-6", E). They 

seem to be identical to the facet of 7. nehalemensis, some 

specimens of which show the facet clearly.

No differences in size of the five radials of any cup 

have been discerned, and no evidence for placement of 

the posterior interradius has been found. Hence, orientation of the cup is unknown.

In longitudinal profile, the pointed proximal part of 

radial plates that projects to the re-entrant angles of 

the stem is nearly plane and is approximately horizontal 

in position—that is, disposed at right angles to the axis 

of the stem. The middle and distal parts of the outer 

surface are very strongly and evenly curved so as to 

form half a circle between the plane of the base and 

the margin of the outer ligament area. The transverse 

profile of radial plates at their midlength is also very 

strongly curved, and the lateral portions of adjoining 

radials meet so as to form a shallow, re-entrant angle. 

The outline of the cup in dorsal view is that of a regular pentagon having slightly rounded sides (text fig. 

35Z>).

The general shape of the radial plates and nature of 

the articular facets of radials belonging to Isocrinus
130 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1950-51

oregonensis seem to be wholly similar to those of 7. 

nehalemensis except that they are larger. Inasmuch as 

the nature of the facets is much better shown in the latter species, detailed description is given in discussing 

specimens referred to 7. nehalemensis.

RAYS EXCLUSIVE OF RADIALS

Arms.—Each of the rays in which the structural 

plan is clearly determinable shows a threefold isotomous branching, so that there are eight outer branches 

to the ray. At least 30 arms can be differentiated with 

certainty, and it seems probable that the total number 

of arms belonging to the species is 40. Bifurcations 

are relatively near the cup, with the unbranched distal 

portion of the rays beyond the last bifurcation more 

than twice as long as the part between this bifurcation 

and the cup. The arms are strongly rounded transversely and fairly slender. Most of the sutures between 

brachials are oblique, with the proximal and distal articular surfaces sloping in opposed directions; thus, 

most brachials are distinctly wedge shaped.

Primibrachs.—There are two primibrachs in each 

observed ray. The first primibrach is a very short 

quadrangular arm segment that is broader along its 

contact with the radial than at its distal margin. The 

nature of the articular surfaces is not determinable 

definitely in the holotype, except that their external 

appearance indicates a nonsyzygial articulation. Paratype L (text fig. 33) of Isocrinus oregonensis and specimens of 7. nehalemensis (text fig. 38) clearly show that 

the articulations between the first and second primibrachs are synarthrial. Presumably, all of the Oregon 

specimens possess this character, which is a distinguishing feature of Isocrinus. The second primibrach is a 

large axillary plate having steeply inclined distal facets 

of even width that support equal branches.

Secundibrachs.—Six or seven secundibrachs occur in 

each main branch. The lowest brachial of this series 

is a short, slightly wedge shaped plate that bears no 

pinnule; the edge on the outside of the ray is not sufficiently longer than that on the inside of the ray to compensate the strongly inclined attitude of the distal surface of the adjoining axillary primibrach. The second 

segment of the secundibrach series is a larger plate that 

also has a longer edge on the outside of the ray, its distal 

articular surface sloping toward the inside of the ray. 

As in all species of Isocrinus, this brachial normally 

bears a stout pinnule at its upper angle, directed toward 

the outside of the ray. This is the most proximal pinnule observed in any specimen, and its position is determined clearly in at least seven rays belonging to different paratypes. Seemingly, this placement of the 

proximal pinnules is a nearly constant character (an 

exception is indicated in text fig. 31, paratype A). The 

third and fourth secundibrachs normally are united by

close suture, forming a syzygial pair; the third segment 

has no pinnule, but the fourth supports one that grows 

toward the inside of the ray. Succeeding secundibrachs are joined by muscular articulation and (excepting axillaries) bear pinnules. Syzygies between the 

second and third secundibrachs, or between the fourth 

and fifth secundibrachs are rarely seen. The axillary 

secundibrachs have evenly sloping distal margins of approximately eq,ual width, supporting subequal branches. 

The structure of rays observed in the holotype and two 

paratypes of Isocrinus oregonensis^ showing distribution of syzygies and pinnules, is indicated in text figures 

31-33.

Tertibrachs.—The number of tertibrachs in different 

branches ranges from 9 to 16. These brachials are like 

those of preceding series except for their smaller size 

and the fact that the second and third tertibrachs (instead of the third and fourth) are joined as a syzygial 

pair; this occurrence of syzygy is almost invariable in 

the tertibrach series, for only one instance of deviation, 

in which the first and second tertibrachs are thus joined, 

has been seen. The first tertibrach (except where it 

forms the hypozygal of a syzygial pair), like succeeding ones which are not hypozygals, is pinnule bearing.

Quartibrachs.—Arm segments of the quartibrach 

series are nearly uniform in size, and have the length 

approximately equal to the width. Articulation between segments is mostly muscular, but there is indication that syzygial pairs occur at intervals of 10 to 12 

segments in some branches (text figs. 31-33). Joints 

cross the branches obliquely, and pinnules are borne on 

opposite sides of the branch by alternate segments.

Bifurcation of the rays.—Three bifurcations are 

found in each of the rays of Isocrinus oregonensis. No 

specimen has been observed in which a ray bears more 

than three bifurcations. This signifies that the terminal part of the arms consists of quartibrachs and the 

total number of arms belonging to & complete crown is 

40. A distinguishing feature of the species seems to be 

the unusual length of the unbranched quartibrach series 

of plates. Several arms of the holotype specimen have 

more than 60 quartibrachs in the preserved portion of 

these arms. Although tertaxils are not certainly identified in some rays, count of quartibrachs of various 

arms are 72 (text fig. 29, arm 5d), 74 (arm 5a), 76 (arm 

5c), 84 (arm 4h), and 88 (arm 5b).

Each ray invariably divides first on the second primibrach. These primaxils are comparatively large plates 

of pentagonal outline.

Bifurcations above the primaxils most commonly 

occur on the fifth to eighth plates of the secundibrach 

series and tenth or eleventh plates of the tertibrach 

series. This is indicated by the following table and 

illustrated in text figures 31-33. One paratype 

(U.C.M.P. A5018A) exhibits unusual irregularity in
LOWER TERTIARY CRINOIDS FROM NORTHWESTERN OREGON 131

length of the secundibrach series, for in four adjacent 

arms the number of these brachials (including secundaxils) is 10, 5, 4, and 8. This specimen shows one 

complete tertibrach series composed of 20 brachials, 

followed by several quartibrachs beyond the tertaxil. 

An adjoining incomplete tertibrach series contains 20 

brachials, no tertaxil being present, signifying that this 

branch must have at least 21 plates in the tertibrach 

series.

Distribution of bifurcations in secundibrach and tertibrach series of 

Isocrinus oregonensis

Axillary

IIBr3 .__. __________

IIBr4 _____- _. _ _

IIBr5 -_.__. ________

IIBr6 -_--_-_-______

IIBr7— ___________

IIBr8 _____. ________

IIBn0 _. ___________

IIIBr6 _-_. _________

Number 

of 

examples

1

2

3

4

3

3

1

1

Axillary

IIIBr7 -_____-__--_-

IIIBr8 __. . _..._._. -

IIIBr10 _. __. _______

IIBr,,-_ — --__- —

IIIBr12 ._ .._.____._

IIIBr13 ------------

IIIBr20 -__-_-__-_--

?IIIBr2 i____-__----

Number 

of 

examples

1

2

6

7

3

2

1

1

The complete unbranched quartibrach series are very 

long, but on most of the paratypes only fragments of 

this part of the rays can be seen. However, paratype 

L (U.S.N.M. 560791L) shows 40 and 41 quartibrachs, 

respectively, in two of the arms (text fig. 33).

Articulation of brachials.—Types of articulation recognized in the rays of Isocrinus oregonensis include 

muscular, syzygial, and synarthrial.

Muscular articulation is much the most common. It 

is distinguished by the presence of a strongly marked 

articular ridge, an outer ligament area containing a 

deep ligament pit, inner ligament depressions, and inner shallow muscular areas, situated on either side of 

the ventrally located muscular notch. An alternating 

shift toward left and right in the position of the ligament pit in the muscular articulations indicates obliquity of position of the articular ridges, but generally 

not enough of the molds of the facets are preserved to 

determine clearly the orientation of the articular ridges.

Syzygial sutures are distinguished by fine radiating 

crenellae that are developed on the part of the articular 

surface adjoining the exterior of the brachials (pi. 19, 

fig. 3). Syzygially j oined brachials are perforated centrally by a canal, and the ventral part of the articular 

facet is nearly smooth.

Synarthrial articulation is characterized by a ridge 

running dorso-ventrally so as to separate broad, shallow ligament areas on the two lateral parts of the adjoining facets; ligament pits are lacking. The first 

primibrach and the primaxil are united by synarthry,

but this type of union is not definitely observed higher 

in the rays, although a tendency in this direction is 

noted in the articulation of the first two brachials following axillary plates or following a syzygial 

articulation.

Distribution of syzygial articulation.—Most commonly, syzygial articulation occurs between the second 

and third brachials of the tertibrach and quartibrach 

series, but in the secundibrach series union of the third 

and fourth plates is generally more common than that 

between the second and third secundibrachs.

Observable distribution of syzygial articulations in 

specimens of Isocrinus oregonensis is summarized in 

the following tabulation, and it is partly illustrated 

in text figures 31-33. In three complete secundibrach 

series and one tertibrach series, no syzygial pairs of 

brachials are present.

The University of California paratypes, which are 

not included in the foregoing table, mostly permit identification of syzygial sutures without difficulty, and in 

general, these specimens follow the pattern discerned 

in study of the external molds belonging to the United 

States Geological Survey collection. The second and 

third brachial of each tertibrach and quartibrach series 

are invariably united by a syzygy, and this applies to 

two of the secundibrach series of paratype U. C. M. P. 

A5018A. Other secundibrach series show syzygial 

union of the third and fourth brachials, as is the rule.

Distribution of syzygial articulations in Isocrinus oregonensis

Brachials united

IIBr3+4_-_---------

IIIBri+2 . ____-_----

IIIBr2+3 --. --------

TTT>*.

IVBr2+3— _________

IVBr8+9 ------

Number 

of examples

3

6

1

22

1

28

1

Brachials united

IVBr»+io-i-~ ------

IVBrio+ii- -- -------

I VBn3+l4- ---------

IVBr18+ i9- -- -------

IVBr2 8+29- ---------

IVBr29+3o-- --------

Number 

of examples

1

1

2

1

1

1

1

Pinnules.—Branchlets that are classifiable as pinnules are borne by all brachials except axillaries, hypozygals, and possibly distal quartibrachs, occurring 

above the non-pinnule-bearing first secundibrach (text 

figs. 31-33). The pinnules are mostly long and moderately stout. Those attached to secundibrachs and 

proximal tertibrachs are somewhat larger than pinnules growing from the unbranched arms, and the 

smallest, weakest pinnules are seen near the extremities of the arms (plates 1-4). The tendency toward 

"rat tail" appearance of the distal portion of arms, 

such as characterizes several species of modern stalked 

crinoids, is evident in Isocrinus oregonensis^ but it is
132 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1950-51

hardly more than incipient. Proximal pinnulars are 

distinctly shorter and stouter than distal segments of 

these branchlets (text fig. 34).

Many pinnules reveal the presence of covering plates 

in erect position along sides of the ambulacral groove, 

although these plates are visible only on pinnules that 

happen to be properly oriented (plate 17; text fig. 34). 

If the ambulacral groove is along an edge of the pinnule nearly in the plane of bedding on which the crinoid is spread out, the erect covering plates may be 

seen in profile; there are four such plates to each pinnular of normal size. In recumbent position the covering plates are not distinguishable.

5b

FIGURE 34.—Brachials and pinnules of the holotype of Isocrinus oregonensis. Compare with text figure 29 for determining position of the arms 4h, 5a, and 5b (midportion of quartibrach series). The small covering plates are in erect position.

COLUMN

The nature of the stalk of Isocrinus oregonensis is 

determined from study of the mold of the proximal part 

of the stem of the holotype specimen, nearly 40 mm 

of which is preserved in its position of attachment to 

the calyx. In addition, it is shown by observation of 

several long segments of the column associated with 

paratype crowns and numerous isolated stem fragments 

that have characters seemingly identical with those of 

the type specimen. The majority of these specimens 

are molds, but several show the well-preserved calcite 

of the stem, which could be removed from the matrix; 

the calcite specimens reveal characters of the articular 

surfaces of both nodal and internodal columnals, as 

well as features of the sides.

The stem is distinctly stellate in cross section, having 

five sharply pointed angles and a corresponding number of re-entrants midway between the angles. At 

first glance, the columnals seem to be very even in width, 

so that the stem is straight-sided and uniform; there is 

hardly a perceptible difference in thickness of the

columnals; nodals are not prominent. Closer observation indicates an unevenness of alternating columnals, 

not only in width and thickness but in the profile of 

the sides; these variations are persistent and regular 

in arrangement, and they are judged "to be diagnostic 

specific features.

Nodal segments of the stem are distinguished by the 

presence of five elliptical scars representing places of 

attachment of cirri or they bear adherent segments of 

the cirri; these branches of the stem are arranged in 

whorls, the attachments being located in each re-entrant 

between points of the nodal. The occurrence of five 

cirri on each nodal is a feature indicating lack of specialization, and this character of the column of Isocrinus 

oregonensis constitutes an easily recognized distinction 

from species of Balcmocrinus. The cirri are directed 

slightly upward, but the scar of attachment, located 

nearer to the proximal margin than to the distal edge 

of the nodal, does not encroach appreciably on the 

adjoining internodal. The surface of the scar is plane 

or gently concave transversely (horizontally) and 

nearly plane in a direction parallel to the axis of the 

stem. The angle between the upward tilted plane of 

the cirrus socket and axis of the column is about 30 

degrees (text fig. 3577-7). A well-defined articular 

ridge divides the scar unequally into upper and lower 

ligament areas, of which the latter is the larger and is 

marked by faint radiating crenellae (plate 23). The 

transverse ridge of the cirrus sockets does not extend 

to their margins but terminates at each end in a rounded 

boss that is slightly steeper on the proximal side (text 

figs. 35#-7; 36J., D-E; 39Z>). Nodals are slightly 

thicker than internodals and the angles project 0.2 mm 

or so laterally beyond the edges of larger internodals.

The proximal articular surface of nodal columnals, 

as in modern pentacrinoids, is marked by strong crenellae that surround and run nearly normal to five lanceolate or ovoid ligament areas; this surface is like 

the normal articular surfaces of internodals. The 

distal (lower) articular surfaces of a number of nodals 

are revealed, for pentacrinoid stems normally break 

readily at the contact of nodals with the subjacent 

internodal, owing to the nearly smooth nature of the 

articulation, termed a synostosis. The under side of 

the nodal carries five gently hollowed areas that extend 

outward to the angles, and each hollow is bordered by 

faint crenellae. The surface of the contiguous internodal bears five gently convex areas that fit into hollows 

of the nodal; this columnal next below the cirrus-bearing nodal has been classed as infranodal or hypozygal 

element of a so-called nodal pair (P. H. Carpenter, 

1884, p. 4), but actually it is an internodal.

Internodal segments are slightly thinner and smaller 

in diameter than the nodals. Typically, there are seven 

columnals of this type between each pair of neighbor-
LOWER TERTIARY CRINOIDS FROM NORTHWESTERN OREGON 133

5 mm

FIGURE 35.—Paratypes of Isocrinus oregonensis in collections of the University of California Museum of Palaeontology. A, B, Side views of paratype A5018O1, showing 

dorsal cup and two primibrachs in each ray. C, D, Side and dorsal view of paratype A5018B; the shaded areas in D are basal plates, which appear enlarged in the lower 

part of the figure owing to an oblique fracture that has resulted in loss of the proximal part of the radial above the basals in this region; the strongly stellate outline of 

proximal columnals (the point at lower right partly broken off) is indicated. E, Side view of paratype A5018A. F, Distal surface of the nodal columnal shown at base 

of the stem fragment illustrated in 7; the five pentameres of the articular face are gently concave and smooth, except for faint marginal crenellae; proximal cirrals are 

attached to each re-entrant side of the nodal. G, An articular facet for attachment of a cirral. H, Cross section of the nodal shown in F along the line a-6, intersecting 

an inclined proximal cirral and showing axial canals penetrating the columnal and cirral. 7, A stem fragment, paratype A5018H, consisting of an epizygal nodal with 

attached cirrals and seven internodals, the uppermost of which adjoins the base of another nodal and is thus identified as a hypozygal plate; the cirrals near the stem 

are much shorter than those of middle and distal parts of the cirri.

10mm

FIGURE 36.—Isocrinui columnals. A, E, Side views of two stem fragments of Isocrinus oregonensia, showing nodals and internodals. 

D, Articular face of the internodal shown at top (proximal extremity) of the fragment illustrated in E, B, C, Articular face and'side 

view of columnals belonging, to /. nehalememis.
134 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1950-51

ing nodals; the internodal midway between the nodals 

is the largest of the group, and the centrally located 

internodals (one above and the other below the dominant internodal) in the remaining space between two 

nodals are next in size; the four other internodals of a 

group are smallest. These differentiated internodals 

represent successive orders of appearance in growth, the 

middle internodal being the first order (that is, initially developed columnal between nodals), the two 

slightly smaller internodals being second order (in time 

of making appearance), and the others constituting a 

third order (final segments in growth succession). It 

is noteworthy that internodals of Isocrinus oregonensis 

belonging to the first and second orders have flaring 

sides that join in a median angulation at midheight 

of the columnals, whereas internodals of the third order 

are straight-sided and lack an angulation; also, the 

first and second order internodals project beyond those 

of the third order at points of the star-shaped stem.

Presumably, nodals are more closely spaced near the 

dorsal cup, in the proximal part of the column of Isocrinus oregonensis and internodals are fewer and thinner, but this is not well demonstrated. The well-preserved segments of columns referred to this species show 

nearly uniform internodalia composed of seven internodals.

The slightly wavy sutures that are seen in side view 

of columnals having crenellate articular surfaces can be 

distinguished from the perfectly plane suture occurring 

at the distal border of nodal segments. Thus, any fragments of the stem that include a nodal can be oriented 

according to position of the column in the living crinoid. 

Amplitude of the crenellae is greatest midway between 

the outer and re-entrant angles of the columnals and in 

a zone located about 0.5 mm inward from the margin. 

Here amplitude of the crenellae (height from crest of 

ridge to adjacent furrow) increases to 0.3 mm. These 

features are excellently shown by many specimens preserved as external molds.

The articular surfaces of internodals (except the 

proximal face of an internodal next below a nodal) are 

marked by five lense-shaped, gently hollowed, smoothfloored ligament areas that extend radially outward 

from the tiny circular lumen nearly to the points of the 

stellate columnal; each ligament area is bordered by 

short, strongly marked crenellae running normal to the 

border of the area, but crenellae near the lumen are 

shorter and less distinct than those bordering the outer 

edeg of the stem. A very fine line resembling a suture 

extends from the lumen to each re-entrant of the margin of the columnals, thus defining pentameres that are 

comparable to those of some Paleozoic stems of primitive type.

Cirri.—The cirri extend outward and slightly upward from the column and then curve downward. They

are nearly uniform in diameter (about 1.5 mm) from 

the base of attachment to their distal extremity, and 

the most nearly complete example has a length of 25 

mm. Proximal cirrals are relatively thin, about nine 

occurring in 5 mm, whereas segments of the medial 

and distal regions are notably thicker, only five cirrals 

in 5 mm. A terminal segment, presumably clawlike 

in form, has not been seen.

Measurements.—A stem fragment having relatively 

large diameter (from loc. 15282) has dimensions as follows: greatest width of nodal 9.0 mm. (pi. 23, fig. 1), 

width across re-entrant angles 5.5 mm, distance from 

lumen to one of the outer angles 4.8 mm, thickness 1.5 

mm-; greatest width of internodal 8.0 mm (pi. 23, fig. 

2), width across re-entrant angles 4.5 mm, distance 

from lumen to outer angle 4.2 mm, thickness 0.8 to 1.2 

mm; a group of eight columnals (nodal and seven internodals) measures 8.8 mm in aggregate thickness (pi. 

23, fig. 3). The very small lumen has a diameter of 0.1 

to 0.2 mm. Cirrus scars on this fragment are 1.5 by 2.0 

mm in width. A smaller stem (loc. 15508, pi. 23, fig. 

9) has maximum, width of 6.5 mm, thickness of nodals 

1.3 mm, internodals 0.7 to 1.0 mm; a group of eight 

columnals measure 7.5 mm in thickness.

DISCUSSION

Discrimination of Isocrinus oregonensis, n. sp., from 

associated crinoid remains that are referred to 7. nehalemensis, n. sp., is based on seemingly constant differences 

in features of the dorsal cup, arms, and stem, as well 

as by the greater average size of specimens belonging 

to /. oregonensis. Plates of the dorsal cup of /. oregonensis are generally less bulbous and more nearly 

confluent with the lower arm plate than in 7. nehcilemensis. Three bifurcations of the rays occur in 7. oregonensis, whereas only two have been observed in 7. 

nehdlemensis. This distinction is not certainly valid 

inasmuch as the longest unbifurcated tertibrach series 

observed in the latter species (text fig. 361£) is 17. 

Syzygial sutures of the secundibrach series rather constantly occur between brachials 3 and 4 in 7. nehalemensis, whereas these are much less regular in 7. oregonensis. 

The stem of 7. oregonensis is distinctly larger on the 

average than that of 7. nehdlemensis, and alternating 

columnals are different in size in contrast to the evenness of columnals belonging to 7. nefialemensis. Also, 

columnals of 7. nehdlemensis are comparatively 

straight-sided rather than horizontally ridged, as in 7. 

oregonensis. Closely crowded short cirri in the proximal part of the stem of 7. nehdlemensis are well shown 

in some specimens (pi. 19, fig. 1; pi. 22, fig. 1; text fig. 

37) but are not evident in 7. oregonensis; this seeming 

distinction cannot be affirmed, however, as a reliable 

basis for discriminating the two species.

A Jurassic crinoid from Wyoming described by 

Springer (1909) as Isocrinus knighti, corresponds to 7.
LOWER TERTIARY CRINOIDS FROM NORTHWESTERN OREGON 135

oregonensis in having the first primibrach joined to the 

axillary second primibrach by synarthry, in the generally oblique disposition of the muscular articular 

ridges of brachials, distribution of syzygies in the 

secundibrach and higher arm series, and in its slender 

long arms, but all of these are characters of the genus 

Isocrinus. This Jurassic species differs from 7. oregonensis in its steeper-sided dorsal cup, the presence of 

only two bifurcations to each ray, and in noteworthy 

differences of the stem, which is pentagonal rather than 

stellate in outline. Except near the crown, internodal 

series of /. knighti range up to 14 columnals, whereas 

the greatest normal number in /. oregonensis is 7 columnals to a single internodal series.

Jurassic crinoid columnals from Utah described by 

Clark (1893, p. 51; 1893a, p. 27, pi. 3, figs. 2A-D) as 

Pentacrinus whitei, correspond to columnals of Isocrinus oregonensis in size, general nature of the articular surfaces, and appearance in side view. Clark's 

species, which probably belongs to Isocrinus, was redescribed and figured by Clark and Twitchell (1915, p. 

27, pi. 3, figs. 3A-C). A stem segment consisting of 

10 attached columnals (Clark and Twitchell, pi. 3, fig. 

3<7) seemingly consists only of internodals.

From Normandy (near Caen, Departement du Calvados) have come several specimens of a Middle Jurassic 

species of Isocrinus, which from 1845 to 1898 was known 

as Pentacrinus nicoleti Desor. This form resembles 

/. oregonensis rather closely in most respects but is much 

smaller. Shape of the dorsal cup, proportions of the 

radial and basal plates and their attitude, the closely 

juxtaposed arrangement of the primibrach series in a 

manner which makes them seem to be part of the dorsal 

cup, and repeated isotomous bifurcations of the rays 

are all nearly identical in Desor's species from France 

and the Oregon specimens described from the Keasey 

formation. Likewise in the column, the nodals, internodals, and cirri, are little different in the two forms. 

Figures and description of I. nicoleti by Bigot (1938) 

show that the Jurassic species mainly differs from /. 

oregonensis in that the dorsal cup more nearly matches 

the proximal columnals in diameter, a synarthry occurs between the first and second secundibrachs, and 

at least five bifurcations occur in some rays. Syzygies 

typically occur between the third and fourth plates of 

the tertibrach and quartibrach series, instead of the second and third, as in /. oregonensis. Some of the specimens of /. nicoleti clearly reveal very diminutive infrabasal plates, and in one (Bigot, 1938, pi. 1, fig. 13), the 

tegmen is almost complete.

From Danian rocks in the type area of Denmark, 

Nielsen (1913, pp. 76-99, pis. 6-10) has described and 

figured 11 species of crinoids, referred to Pentacrinus. 

The Danian deposits commonly are classed as belonging 

at the top of the Upper Cretaceous succession, but some

paleontologists consider them to be of Tertiary age. 

Diagnostic Cretaceous invertebrates are lacking, 

whereas the gastropods (Ravn, 1933, p. 9), some other 

mollusks (Vincent, 1930), and bryozoans (Canu and 

Bassler, 1933) indicate affinities with deposits elsewhere 

that are classed as Paleocene or Eocene. Except for 

stem segements consisting of several articulated columnals, Nielson's pentacrinoid specimens are all dissociated fragments. Some of them clearly belong to 

Balanocrinus, as noted by Sieverts-Doreck (1943, p. 

150), but none are surely assignable to Isocrinus and 

none closely resemble parts of 7. oregonensis.

Isocrinus holsaticus Jaekel (1904) from Upper Cretaceous rocks of northern Germany has a dorsal cup and 

compact, laterally adjoined lower brachials similar to 

corresponding parts of 7. oregonensis, except for the 

proportionally larger basals and steeply upsloping attitude of the radials; characters of the column (except 

for the stellate proximal segment) are unknown.

Isocrinus crassitdbulatus Biese (1930, p. 702, pi. 51) 

from Upper Cretaceous (Senonian) rocks of Germany 

possesses infrabasal plates, and has plates of the basal 

circlet laterally in contact. The arms are much thicker 

and the brachials very much shorter than in 7. oregonensis. Other features, such as the marked median 

thinning externally of the first primibrach, distinguish 

this Cretaceous species. Biese (1930, p. 716) consid-' 

ered his species similar to Cainocrinus beaugrandi de 

Loriol, which he erroneously defined as the type species 

of Cainocrinus Forbes (1852) and which Bather (1898, 

p. 253) referred to Isocrinus. De Loriol's species, from 

Upper Jurassic strata of France, is too unlike 7. oregonensis to merit comparison.

Occurrence—Middle member of the Keasey formation, lower Oligocene(?), northwestern Oregon; most 

abundantly at U. S. Geological Survey locality 15318, 

on Nehalem River, near Mist, Oregon.

ISOCRINUS NEHALEMENSIS MOORE AND VOKES,

N. SP.

PI. 19, fig. 1; pi. 20, figs. 1, 2; pi. 21, fig. 2; pi. 22, fig. 1; pi. 23, 

figs. 4, 7, 11; text figs. 35-38, 39A-C.

Description of this species is based on three fairly 

complete lower portions of crowns and numerous stem 

fragments. All of the crowns and many of the stem 

fragments come from the locality near Mist, Oreg., 

that has yielded most of the material referred to Isocrinus oregonensis. Isolated columnals and stem fragments assigned to 7. nehalemensis occur in at least two 

other northwestern Oregon localities. The crowns are 

external molds prepared by removing the more or less 

decomposed calcite of the fossils by etching in acid. 

Several segments of the column are also external molds. 

A few stem fragments are well-preserved specimens 

composed of calcite that were obtained free from 

matrix.
136 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1950-51

SUMMARY OF DESCRIPTION

Isocrinus nehalemensis is a relatively small species, 

which has strongly bulbous cup plates. Infrabasals 

not observed. Basals protrude at the interradial corners, in some specimens projecting downward as bluntly 

rounded spines. Radials thick, strongly rounded near 

the facets, which occupy the full distal extremity of 

these plates and bear a broad dorsal ligament area.

Arms slender, probably four in each ray, making a 

total of twenty at summit of the crown. Syzygies rare, 

except between the third and fourth secundibrachs and 

the second and third tertibrachs.

Stem stellate to pentagonal in section. Radial pores 

occur between columnals, which are very uniform in 

most characters. Nodals are only slightly thicker than 

internodals and they do not project laterally; they bear 

large elliptical cirrus sockets, which tend to impinge on 

the proximally adjoining internodal. Articular facets 

have long narrow floors bordered by conspicuous short 

crenellae. Seven internodals normally occur between 

each neighboring pair of nodals, except in the proximal 

part of the stem, where internodals are fewer. Cirri 

are comparatively short, directed upward, and arranged 

in whorls of five.

DESCRIPTION OF SPECIMENS 

HOLOTYPE

One of the crowns (U.S.N.M. 560792K) that has 

longest attached arms is selected as the holotype of Isocrinus nehalemensis. The proximal part of the stem 

is attached to the dorsal cup. The height of the preserved part of the crown of the holotype specimen is 40 

mm and the width about 60 mm. The dorsal cup is 

10 mm in diameter, and the stem is 4 mm across at its 

proximal extremity (pi. 21, fig. 2).

PARATYPES

Paratype C (U.S.N.M 560793C) consists of the lower 

part of a crown in which the dorsal cup, seen from the 

side, is fairly well shown, together with an attached 

proximal part of the stem bearing numerous short cirri 

(pi. 19, fig. 1).

Paratype G (U.S.N.M. 560793G) is the lower part of 

a crown 30 mm high and about 25 mm wide (pi. 20, fig. 

2). The dorsal cup is 7.5 mm in diameter.

Paratype H (U.S.N.M, 560793H) (not figured) is 

like the other specimens except that it is a little more 

completely imbedded in the matrix- and the available 

fragment is more than a half specimen. The greatest 

width of the exposed part of the crown is 25 mm, and 

its height is 18 mm. The attached proximal part of 

the stem is 20 mm long, and its greatest width is 5 mm. 

Diameter of the dorsal cup is 8 mm, and its height 

mm.

An external mold of a relatively long stem segment

FIGURE 37.—Paratype C of Ifocrinus nehalemensis. This drawing corresponds to 

the photographic illustration given in plate 19, figure 1. Lower brachials abut 

one another laterally in manner indicating that they are virtually parts of the dorsal 

cup. The proximal part of the stem contains closely spaced nodals, which bear 

whorls of five short, upwardly directed cirri.

(52 mm) is not associated with a crown; this fossil, 

designated as paratype I (U.S.N.M. 5607931), shows 

regularly distributed nodal- and inter-nodal sequences 

and the proximal part of a few cirri attached to nodals 

(pi. 20, fig. 1). Other paratypes consisting of stem 

fragments preserved as calcite (U.S.N.M. 560904A, B) 

are illustrated in plate 23, figs. 4, 7,11.

Paratype J (U.S.N.M. 560793J) is the mold of a 

dorsal cup with attached lower arms and about 40 mm 

of the attached proximal part of the stem, bearing 

numerous cirri. The height of the attached crown is 

30 mm, its width is 28 mm, and the diameter of the 

dorsal cup is 10 mm. Greatest width of the preserved 

part of the column is 5 mm.

DORSAI. CUP

The dorsal cup of Isocrinus nehalemensis generally 

corresponds to that of /. oregonensis except for its 

slightly more bulbous plates. This greater convexity 

of the plates applies both to radials and basals. In 

paratype H, the basals project downward distinctly 

as short, bluntly rounded spines, but in other specimens 

these plates appear as subtriangular convex protrusions 

between the lower parts of the radials.

RAY STRUCTURE

No specimen referable to Isocrinus nehalemensis has 

been observed in which there are more than two successive bifurcations in a ray. The available material, 

however, is insufficient to establish whether this is a 

characteristic feature of the species. The longest preserved portion of the arms is seen in the holotype specimen (U.S.N.M. 560792K) (pi. 21, fig. 2; text fig. 38), 

which in one ray has 11 and 12 tertibrachs and in 

another 14 and 17 tertibrachs. The last-mentioned 

numbers belong to the regenerated right branch of one 

of the rays.
LOWER TERTIARY CRINOIDS FROM NORTHWESTERN OREGON 137

Occurrence of syzygial articulations is rather constant between the third and fourth brachials of the 

secundibrach series (fig. 38) and between the second and 

third brachials of the tertibrach series. All twelve 

observed tertibrach series show syzygies between the second and third tertibrachs. Two arms (fig. 38.2") show 

11 and 14 tertibrachs respectively, without a syzygial 

union. The distal articular surface of typical hypozygals, showing the fine crenellae along the external edge 

of brachials, is illustrated in text fig. 39(7.

The articular facet of the radials is nearly as long 

as wide (text figs. 39J., B). It is divided into two

parts by a straight articular ridge running from one 

upper angle of the radial to the other. On the externaf 

side of this ridge is the outer ligament area, consisting 

of a very broad gentle concavity, bounded on its curved 

outer edge by abrupt bending into confluency with the 

outer face of the radial. This border of the ligament 

area is not sharply defined. The maximum width of 

the outer ligament area and of the articular ridge of 

a radial 5 mm in width is 5 mm, and its greatest length, 

in the middle, measured from the articular ridge to the 

abrupt bending at the outer border is 1.3 mm. A very 

sharply defined, deep ligament pit, semicircular in plan,

EXPLANATION

<3 — *Syzygy ^Pinnule

*% * Pinnule inferred 

33, 

-*-Synarthry

Vo o T T • Muscular articulation 14 ,'

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FIGURE 38.—Ray structure of holotype and two paratypes of Isocrinus nehalemensis. The holotype is represented by the letter K. Paratypes G and J are shown at the !«£* 

of the figure. The regenerated branch belonging to one of the rays of the holotype is of interest, because the beginning of regenerated parts of the ray is located at 

point of normal syzygial union in ossicles of the secundibrach series, that is, between IIBrj and IIBn.
138 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1950-51

o.1mm

FIGURE 39.—Radial plates and syzygial articulation of Isbcrimu nehalemensis, and 

cirrus socket of /. cregonensis. A, B, Views from two slightly different angles oi a 

radial plate of paratype G of /. nehalemensis, showing outer curvature and features 

of the articular facet. A', B', profile views, indicating longitudinal curvature and 

showing the deep ligament pit. C, Distal surface of two hypozygals. C', Cross 

section Of one of these plates. D, Nodal and two adjoined internodals of /. cregonensis, showing cirrus socket on nodal.

is centrally located near the inner edge of the outer 

ligament area, The straight side of the pit that adjoins the transverse ridge is vertical and is finely striated, whereas the curved outer border slopes steeply 

toward the base of the pit about 0.5 mm below the surface of the area. On the average, the pit is 0.5 mm 

by 0.85 mm. The inner ligament area is subtrapezoidal 

in outline, and lies nearly in the same plane as the 

outer ligament area, from which it is separated by the 

articular ridge. Its lateral margins are elevated in a 

low but sharp ridge, outside of which is a slope to the 

interradial suture. The inner margin of the area is 

deeply indented by an inter-muscular notch and strong 

furrow that lead to a central perforation in the position of the central canal close to the articular ridge 

and opposite to the outer ligament pit. Muscle areas 

on the two sides of the furrow are shallowly concave 

and are not marked by oblique ridges. The plane of 

the whole articular facet, including outer and inner 

ligament areas, slopes outward at an angle of 30 to 40 

degrees to the plane of the base of the cup or that 

formed by the five articular ridges of the radials.

COLUMN

The column of Isocrinus nehalemensis is distinguished mainly by its relatively small diameter and by 

the uniformity in size of successive columnals. In 

these respects, the column (pi. 23, figs. 4,7,11; text figs. 

36B, C) is readily distinguished from that of /. oregonensis (pi. 20, fig. 1; pi. 23, figs. 1-3, 5-6, 8-10; text 

figs. 351, 36A, D, E). The sides of the columnals of 

/. nehalemensis are relatively straight longitudinally, 

the horizontally ridged appearance of the columnals of 

/. oregonensis in side view being conspicuously absent. 

/. nehalemensis typically has seven internodals in each 

group of columnals occurring between the nodal segments except in the proximal part of the stem, where 

nodals are closely spaced (text fig. 37). Both nodals 

and internodals are characterized by the presence of a 

pit at re-entrant angles of the stem in the position of 

the articular sutures.

Nodal segments.—The nodal columnals of Isocrinus 

nehalemensis are only slightly thicker than the internodals (pi. 23, fig. 11). For this reason, and because 

they do not project laterally, they are less conspicuous 

than in stem segments of /. oregonensis. Each of the 

five re-entrant angles of the nodals bears a large elliptical cirrus socket that is perforated slightly above the 

center by the small opening leading to the axial canal 

of the stem. A short articular ridge extends laterally 

from the central opening of the socket, terminating in 

a rounded elevation. The socket occupies nearly the 

entire thickness of the nodal but tends to impinge 

slightly more on the proximal than the distal margin. 

The upper or proximal articular surfaces of the nodals 

bear crenellae like those borne by all internodals except 

one that adjoins a nodal on the distal side. The crenellate edge of the articulations can be seen clearly in side 

view of the stem. The distal surfaces of the nodals are 

smooth and very gently convex. The articulation 

along this surface is a synostosis, along which the stem 

parts readily.

Internodal segments.—Internodal series of columnals 

belonging to Isocrinus nehalemensis are uniformly 

about 5.5 to 6 mm in aggregate thickness. Individual 

internodals range in thickness from 0.8 to 1.0 mm, except near the crown, where all columnals are thinner 

than in mature portions of the stem. The articular 

surfaces of the internodals are strongly petaloid and 

marked by prominent short crenellae, which, as in /.
LOWER TERTIARY CRINOIDS FROM NORTHWESTERN OREGON 139

oregonensis, reach inward almost to the small round 

lumen (pi. 23, fig. 7; text fig. 36B). The proximal surface of the most proximal internodal of each group carries a smooth articular surface, which is slightly concave and matches the synostosial articular surface of the 

adjoining nodal plate (pi. 23, fig. 4). Carpenter (1884, 

p. 18) notes that re-entrant angles of the proximal part 

of the column belonging to some modern pentacrinoids 

contain "interarticular pores." Similar pores are observed in the column of /. nekalemensis. These radial 

pores are produced by apposition of faint grooves radiating from the center of columnals along the articular 

surfaces. The grooves are largest near the lumen and 

shallow near the margin, but they do not reach the 

lumen and have no connection with it. The radial pores 

of the column of /. nehdlemensis seemingly are not confined to youthful (proximal) parts of the column, for 

they are clearly evident on mature stem segments having the normal full number of evenly sized internodals 

(pi. 23, fig. 11). Radial pores are not observed even 

in the proximal region of well-preserved stem segments 

of /. oregonensis. This feature, along with other characters of the column, distinguishes /. nehalemensis from 

7. oregonensis.

Cirri.—In Isocrinus nehalemensis, the cirri are 

numerous but comparatively short. They are directed 

upward and seemingly do not tend to become pendent, 

as is common in /. oregonensis. Proximal cirrals are 

distinctly shorter than those in the middle and near the 

extremity of cirri. Adjacent to the stem, the cirri are 

elliptical in section but become subcircular a short distance outward from the socket. The shape of terminal 

cirrals is not known.

DISCUSSION

Comparison of Isocrmus nehalemensis with /. oregonensis has been given in the discussion of the latter 

species. In the study of 7. nehalemensis, attention has 

been given to the possibility that this group of crinoids 

represents the young of 7. oregonensis. This is a reasonable postulate in view of their association together 

and various structural resemblances. Information derived from additional specimens may modify conclusions which seem to be well supported by characters 

observed on the specimens now available for study. 

7. nehalemensis is judged to be distinguishable from 

7. oregonensis on features both of the crown and of the 

column.

Characters of the articular surfaces and sides of the 

columnals of Isocrinus nehdlemensis are rather closely 

similar to those of 7. californicus Clark (in Clark and 

Twitchell, 1915, p. 21, pi. 1, figs. 2a-c from the Upper 

Triassic of California. The diameter of the columnals 

of 7. californicus is reported to be 2 to 5 mm and the 

thickness of 0.5 to 1 mm. Only a few internodal series

of Clark's species are known. Despite their similarity 

to typical specimens of the stem of 7. nehalemensis, the 

two forms are not thought to be allied specifically.

Occurrence—Middle member of the Keasey formation, lower Oligocene(?), northwestern Oregon. Most 

abundant remains are recognized in material collected 

at U. S. Geological Survey locality 15318 near Mist, 

Oregon. Columnals from Survey localities 15268 and 

15985 are also referred to this species.

SPECIES OF ISOCRINUS DESCRIBED FROM TERTIARY 

ROCKS IN OTHER PARTS OF THE WORLD

Five species that seem referable to Isocrinus have 

been described from Tertiary rocks of areas outside of 

North America, and another species, assigned to Isocrinus, is recorded from undifferentiated Tertiary deposits. The five species are Isocrinus cParchiaci Pasotti 

(1929, pp. 80-82, 84-86, pi. 2, figs. 12-15), from Paleogene rocks of Gassino, Italy; Isocrinus gastaldi (Michelotti) (described as Pentacrinus gastaldi Michelotti, 

1847, p. 59, pi. 16, fig. 2), from Eocene, Oligocene (Tongrian), and Miocene rocks of northern Italy and from 

Miocene of southern France; Isocrinus hungaricus 

Vadasz (1915, pp. 85, 92-93, pi. 7, figs. 33-35), from 

Miocene beds of Hungary; Isocrinus stellatus Szalai 

(1926, p. 341), also from the Miocene of Hungary; and 

Isocrinus tridactylus (Quenstedt) (1874-76, p. 268, pi.

99. fig. 170), from Tertiary rocks of Spain. Crinoid 

remains referred to Isocrinus gastaldi are illustrated 

also by de Loriol (1897, p. 115, pi. 4, figs. 15-18), Noelli 

(1900, p. 19, pi. 1, figs. 1-32), and Albus (1931, p. 279, 

pi. 10, figs. 1, 4-5, 7, 11,14-15). All of these reported 

species are represented by fragments of the column only. 

Additional Tertiary forms referred to Pentacrinus 

(27 species) probably belong in other genera. Some 

of these are referable certainly to Balanocrinus, and 

others may be assignable to Isocrinus or other genera of 

the Isocrinidae. Definite generic identification seems 

to be impossible for the fragments of columns represented among these fossils. Only two of the Tertiary 

species of "Pentacrmus" merit individual notice here 

by reason of their occurrence in the Pacific province. 

There are "P." ariakensis Yokoyama (Nagao, 1928, p.

100. pi. 18, fig. 17), from lower Tertiary (Paleogene) 

rocks of Kyushu, in southern Japan; and "TV' stellatus 

Hutton (Tate, 1894, p. 122), from deposits of undetermined position in the Tertiary succession of New 

Zealand and southeastern Australia. The generic 

classification of the Japanese columnals cannot be defined from a study of the description and figures, but 

they are not conspecific with either of the Keasey 

crinoids. Illustrations of the New Zealand species or 

of specimens from Australia referred to it, have not 

been published. Consequently, "TV' stellatus Hutton 

is not now recognizable. If the species proves to be-
140 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1950-51

long to Isocrinus and /. stellatus Szalai, from Hungary, 

is rightly placed generically, the latter is a homonym 

of Button's species.

Comparison of illustrations of other Tertiary crinoids with the fossils here described from Oregon 

brings to light some that have more or less resemblance 

to Isocrinus oregonensis or 7. nehalemensis/ others are 

obviously different in one or more characters. Because 

of geographic remoteness of those described species 

based on fragments of columnals, and because most of 

them differ in age from the Oregon fossils, there is 

very little possibility that the crinoids here described 

as new species may actually represent already described 

forms occurring in Tertiary rocks of some other part of 

the world. Even where fragments of the column seem 

to correspond closely, as in specimens of Isocrinus californicus Clark, from the Triassic of California, and /. 

nehalemensis from lower Oligocene rocks of Oregon, 

possibility of specific identity is very unlikely.

PALEOECOLOGY OF THE KEASEY CRINOIDS 

GENERAL STATEMENT

The local abundance of well-preserved remains of 

stem-bearing crinoids in the Keasey formation of northwestern Oregon is a highly exceptional paleontological 

record. Except for two or three species that are represented by cups, all described forms of Tertiary crinoids 

in the world are identified on the basis of fragments of 

the stem or arms or both. Preservation of the Keasey 

crinoids, among which several specimens show stem and 

arms attached to the dorsal cup and in which articulated groups of brachials and columnals are the rule 

rather than the exception, indicates burial of these organisms in very quiet water. It is desirable to make 

such observations as are possible on the environment of 

Keasey sedimentation in the area where the fossil crinoids have been found.

Paleoecological evidence relating to occurrence of the 

Keasey crinoids includes lithologic features, the nature 

of bedding, and other physical characters of the rocks 

containing the crinoids and the nature of organic remains associated with the fossil crinoids.

As pointed ou the description of the lithology of the 

middle member of the Keasey formation in which the 

crinoids occur, dominance of tuffaceous volcanic materials is an obviously important physical character. The 

sediment in which the crinoids and other fossils are 

imbedded is noncalcareous, medium to fine-textured, 

and, although bedded, is not well laminated. Scattered small "pebbles" of ashy material are observed in 

the rock, and the manner in which it swells on wetting 

and breaks into conchoidally shaped fragments suggests the mixture of a good deal of bentonitic material. 

It seems appropriate to ask whether the volcanic detritus was carried to the point of deposition on-the sea 

floor by marine currents or whether much of it may 

have been carried through the air so that on falling 

into the water it could settle quietly to the bottom. 

Whether carried in this manner or transported by currents, we wish to know whether the sea bottom was 

shallow, of intermediate depth, or very deep. By 

"shallow" we mean anything from the strand line to 

the commonly accepted lower limit of wave agitation 

at 100 fathoms. "Intermediate depths" may be designated for present purposes as ranging from 100 to 500 

fathoms (600 to 3,000 feet). As "deep water" we 

designate all depths of the coastal area of early Tertiary sedimentation in the Oregon region lying below 

500 fathoms. As indicated by Shepherd (1948) and 

others, all of these depth conditions exist today close to 

the Pacific border of the continent, and in many areas 

there is very abrupt local variation in depth environment. Accordingly, in studying the Keasey deposits, 

one may reasonably postulate deep-water conditions as 

somewhat arbitrarily defined above as well as intermediate and shallow-depth waters.

PHYSICAL FEATURES

Pertinent physical features bearing on interpretation 

of sedimentation at the crinoid localities in the Keasey 

formation- include nokonly the texture and bedding of 

the deposits in these areas but regional thickness, variation in thickness, and texture of the deposit as known 

throughout the Nehalem Basin. The recorded total 

thickness of the Keasey formation is 1,800 to 2,200 feet 

(Warren and Norbisrath, 1945, p. 220), although satisfactory measurement has been made at only one locality. 

The comparatively great thickness of the Keasey deposits, coupled with the strongly tuffaceous nature of 

the middle and upper members, indicates that if the 

site of sedimentation was in moderately deep, or deep 

water, the area was not far removed from land on which 

a number of explosive volcanic vents were recurrently 

active. The middle member of the Keasey is described 

as unstratified siltstone. Lack of bedding and general 

uniformity through considerable thicknesses of the deposit are not features to be expected in the littoral zone 

and suggest offshore conditions where the bottom was 

not agitated by waves or affected by currents. Analysis 

of all known physical characters associated with the 

crinoid-bearing part of the Keasey formation therefore 

indicates nearness (at most a few tens of miles) to land 

and a sea bottom ranging from intermediate depth to 

greater than 500 fathoms. A considerable fraction of 

the volcanic materials including light ashy constituents 

may have been carried through the air or in shallow 

currents so as to sift down through the moderately 

deep water to the surface of sedimentation.
LOWER TERTIARY CRINOIDS FROM NORTHWESTERN OREGON 141

ORGANIC EVIDENCE

The nature of the crinoid remains has already been 

cited as indicative of quiet, fairly deep water. Agitation on the bottom by waves or currents, which would 

surely have resulted in disarticulation of the crinoid 

remains, is inconsistent with nearly all the observed 

crinoid fossils.

Associated with the crinoids are common, wellpreserved mollusks, including pelecypods and gastropods, Foraminifera, and various other invertebrates. 

One nearly complete specimen of a spinose ophiuroid 

was found resting against crinoid arm fragments. 

Rather unexpected is occurrence of fairly large, wellpreserved leaves, which, in unweathered condition, appear black by reason of the film of carbon derived from 

tissue of the leaves. Two such leaves are illustrated in 

plate 22, figure 2. These have been identified by Dr. 

R. W. Brown, who states: *

Several fragmentaiy, dicotyledonous leaves of land plants 

were found with the crinoid. One represents an oak, Quercus 

consimilis Newberry, a species common in the Oligocene and 

Miocene floras of Oregon, Washington, and Idaho. The others 

are probably a species of bayberry, Myrica sp. These leaves 

were tough enough to resist complete destruction while being 

swept out to burial in the sea.

Referring to the mollusks, we note that temperature 

control is an important factor in the depth distribution 

of many species, for the same species are found in relatively shallow waters at high latitudes and in deep 

waters in tropical regions. Thus, Lima (Acesta) excavata (Fabricius), the type of Acesta, occurs at depths 

of 150 to 300 fathoms off the coast of Norway and at 

1,450 fathoms off the Azores Islands; and Turcicula 

bairdii Ball, the modern equivalent of the principal 

guide to the lower faunal zone of the Keasey, occurs 

at 27 fathoms in the Behring Sea and from 238 to 822 

fathoms off the coast of Washington to the Coronado 

Islands.

It is difficult at the present stage of the study of the 

Keasey molluscan fauna to make any certain valuations 

of its modern equivalents; however, there is a general 

absence of forms that may be considered as wholly confined to the tropical regions, although some subtropical 

types are present. Hence, it seems most probable that 

the general equivalents of the Keasey fauna will be 

found in the southern portion of the California faunal 

province as defined by Bartsch (1921, p. 507) or of the 

Californiaii province (restricted) of Schenck and Keen 

(1936). Within this area, Solemya (Acharax) johnsoni Ball, the type of the subgenus Ac harass, is reported 

as ranging from 200 to 1,100 fathoms; Delectopecten 

randolphi (Dall) from 300 to 1,100 fathoms; and D. 

randolphi tillamookensis (Dall) from 100 to 1,100 

fathoms (Woodring, 1938, pi. 3). Minormalletia, a

997130—53——3

rather abundant form in the Keasey fauna, is known 

in Recent faunas only from two species dredged from 

493 fathoms off the Pacific coast of Mexico. The presence of these types, together with large, thin-shelled 

gastropods, such as Olequahia schencki Durham, and 

dominance of Turridae, if not strictly in numbers of 

individuals, certainly in number and diversity of genera and species, all suggest that the Keasey formation 

was deposited in relatively deep waters. This is even 

more strongly indicated by the complete absence of the 

common shallow-water molluscan types present in the 

normal west coast Tertiary marine sequence. Such 

common genera as Ostrea, Mytilus, Volsella, Macrocallista, Spisula, Macoma? Solen, Crepidula, and many 

others that are represented in the faunas of both the 

underlying Cowlitz and the overlying Pittsburgh Bluff 

formations are wholly absent in the Keasey fauna. The 

only essentially shallow-water type so far noted is 

represented by a single, rather large, and thin-shelled 

Acmaea; it may well have been carried into the area 

on a large alga.

This concept of relatively deep waters over the area 

during the deposition of the Keasey formation also 

seems to receive a measure of confirmation in the fact 

that the great majority of the pelecypods have the 

valves in association, even such weakly hinged types as 

Solemya, Delectopecten, and Lima (Acesta) being usually not markedly disturbed. Furthermore, the several crinoid specimens here described, as well as the 

others that have been recovered from this locality, show 

no evidence of strong disturbance such as would result 

from even moderately weak wave or current action. 

Likewise, a highly spinose ophiuroid specimen, which 

was found between arms of a crinoid crown at U. S. 

Geol. Survey locality 1531$, shows no signs of disarticulation. The lack of disarticulation of so many 

crinoid crowns seems to negate the suggestion that the 

crinoids and associated invertebrates are relatively 

deep- or cool-water types that lived in a zone marked 

by an upwelling of cool waters such as occur at a number of localities along the California coast. Furthermore, many of the shallow-water genera, which are 

absent in the Keasey fauna here discussed, are represented in the modern Aleutian cool-water faunas. 

They would be expected to occur in the Keasey fauna 

if its presumably deep-water elements were present as 

a result of such upwelling.

The organic evidence, therefore, seems to point to 

deposition in relatively deep waters, below the limit of 

effective wave or current action, in a region not far from 

the old coast line.

2 A form previously identified and listed as "Macoma n. sp." bas 

proved to be an unusually Maooma-like form of Tellina.
142 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1950-51

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off the California coast: Canyons and tectonic interpretation : Geol. Soc. America Spec. Paper 31, pp. i-xiii, 1-171, 

pis. 1-18, charts 1-4, figs. 1-42.

SIEVEBTS, HEKTHA, 1932, Jungertiare Crinoiden von Seran und 

Borneo: Neues Jahrb, Beilage-Band 69, Abt. B, pp. 145- 

168, figs. 1-12.

SIEVERTS-DORECK, HERTHA, 1943, Zur Morphologic und systematischen Stellung von Balanocrinus: Neues Jahrb., BeilageBand 88, Abt. B, pp. 136-155, pi. 15, text figs. 1-10.

SIEVERTS-DORECK, HEETHA, and BlESE, WALTEE, 1939, Supplementum ad Crinoidea triadica, jurassica, cretacea et 

caenozoiea: Fossilium Catalogus, 1: Animalia, pars. 88, 

pp. 1-81.

SPRINGER, FRANK, 1909, A new American Jurassic crinoid: U. S. 

Nat. Museum Proc., vol. 36, pp. 179-190, pi. 4.

———— 1913, Crinoidea : in Zittel-Eastman, Textbook of Palaeontology, vol. 1, pp. 173-243, figs. 267-346, MacMillan, London.

———— 1918, A new species of fossil Pentacrinm from the East 

Indies. Nederlandsche Timor-Expeditie II: J a a r b. 

mijnwezen, Jaarg. 45,1916, pp. 1-8, pi. 1.

———— 1925, A Tertiary crinoid from the West Indies: U. S. 

Nat. Museum Proc., vol. 65, art. 3, pp. 1-8, pi. 1.

———— I925a, Occurrence of the crinoid genus Apiocrinus in

America: U. S. Nat. Museum Proc., vol. 67, art. 18, pp.

• 1-5, pi. 1.

—— I925b, The genus Pentacrinus in Alaska: U. S. Nat. 

Museum Proc., vol. 67, art. 5, pp. 1-7, pi. 1.

SZALAI, TIBOR, 1926, Daten zur Frage der Tertiarcrinoideen:

Foldtani Kozlony, Band 55, 1925, pp. 169-174 (Hungarian),

339-341 (German), pi. 1. 

TATE, RALPH, 1894, Critical list of the Tertiary Mollusca and

Echinodermata of New Zealand in the collection of the

Colonial Museum: Rept. Geol. Survey New Zealand, 1892-

93, pp. 121-127. 

VADASZ, M. E., 1915, Die mediterranen Echinodermen Ungarns:

Geologica Hungarica, tomus 1, fasciculus 2. 

VINCENT, E., 1930, Etudes sur les Mollusques montiens du

Poudengue et du Tuffeau de Ciply: Mus. royal histoire

nat. Belgique Mem. 46, pp. 1-115, pis. 1-6, text figs. 1-37. 

WANNER, J., 1938, Balanocrinus sundaicus n. sp. und sein Epoke

aus dem Altmiocan der Insel Madura: Neues Jahrb., Beilage

Band 79, Abt. B, pp. 385-402, pis. 10, 11. 

WARREN, W. C., GRIVETTI, R. M., and NORBISBATH, HANS, 1945,

Geology of northwestern Oregon west of Willamette River

and north of latitude 45°15': U. S. Geol. Survey Oil and

Gas Invs. Prelim., Map 42. 

WARREN, W. C., and NORBISRATH, HANS, 1946, Stratigraphy of

upper Nehalem River Basin, northwestern Oregon: Am.

Assoc. Petroleum Geologists Bull., vol. 30, pp. 213-237. 

WEAVER, C. E., 1943, Paleontology of the marine Tertiary formations of Oregon and Washington: Washington Univ.

[Seattle] Pub. in Geology, vol. 5, pts. 1-3, pp. i-xiii, 1-789,

pis. 1-104. 

WEAVER, C. E., et al., 1944, Correlation of the marine Cenozoic

formations of western North America: Geol. Soc. America

Bull., vol. 55, no. 5, pp. 569-598. 

WELLER, STUART, 1907, A report on the Cretaceous paleontology

of New Jersey: New Jersey Geol. Survey, pp. 275-305, pis.

6-18. 

WOODRING, WENDELL P., 1938, Lower Pliocene mollusks and

echinoids from the Los Angeles Basin, California, and their

inferred environment: U. S. Geol. Survey Prof. Paper 190,

pp. 1-67, pis. 1-9, figs. 1, 2. 

YOKOYAMA, MATAJIRO, 1911, Some Tertiary fossils from the

Miike coal field: Jour. Coll. Sci., Imp. Univ. Tokio, vol. 27,

art. 20, pp. 1-16, pis. 1-3.

INDEX

[Italic numbers indicate descriptions

A Page 

Abstract.____________.____________________________ 113

(Acestd) excavata, Lima______________________________ 141

Lima....................... _________________ 141

oregonensis, Lima............................. 115, 118

(Ackarax) johnsoni, Solemya....... ___________________ 141

willapaensis, Solemya......-.--..-..._.----__.__. 119

Acila (Truncacila) nekalemensis........ _________ 113, 118, 119

Acknowledgments_ ________________________________ 118

Annacrinus. _______________________________________ 121

ariakensis, Pentacrinus. _____________________________ 139

Austinocrinus _ _„_____________________________ 121, 122, 123

cubensis. ______________________________________ 117

B

bairdii, Turcicula.................... ________________ 141

Balanocrinus. . _______________ 121, 122, 123, 124, 132, 139

cubensis. ______________________________________ 117

haitiensis.......---..----.---..--.-_-____.___ 116, 117

subbasaltiformis _____________________________ 118, 123

bassleri, Himerometra.............................. 116, 117

beaugrandi, Cainocrinus... ___________________________ 135

bentsonae, "Gemmula" _____________________________ 115, 119

(Boreoscala) condoni, Epitonium_____________________ 119

Bourgueticrinus cylindricus. __________________________ 117

Brown, R. W., quoted--.__________________ 141

Bruclarkia. ________________________________________ 119

n. sp_ — __ ———— _____ —— — —————— ________ 115

bryani, Pentacrinus.. ............................... 117

C

Cainocrinus...................................... 121, 123

beaugrandi..................................... 135

californicus, Isocrinus. ______________________________ 140

Calyptraea diegoana................................. 119

Cancellaria n. sp__--__-______________--___________ 115, 119

caroliniana, Glenotremites (Palaeantedon)............. 116, 117

Cenom'nws_____________________________________ 121, 124

chehalisensis, Yoldia (Portlandella) ____________________ 119

clarki, Isognomon.................... _______________ 119

Pitar.............. _________________________ 115

Pitar (Lamelliconcha)............................ 119

Classification, suprafamilial___________________________ 121

Cochlodesma........................................ 119

columbiana, Turdcula............................. 115, 118

Columbia River basalt, map_________________________ 114

condoni, Epitonium............... ________________ 115, 118

Epitonium (Boreoscala).--. ____________________ 119

conoideus, Microcrinus.---------------------------- 116, 117

Zenometra... ___________________________________ 117

Cowlitz formation._____________________________ 114

crassitabulatus, 7s0cnnws_____________________________ 135

Crenella porterensis................................ 115, 119

Crepidula. _________________________________________ 141

Crinoid material, discovery__________________________ 113

studied..._________________________ 120

cubensis, Austinocrinus...-------------..-.--.-.---.. 117

Balanocrinus. __________________________________ 117

cylindricus, Bourgueticrinus. _________________________ 117

Rhizocrinus. ___________________________________ 117

Cypelometra iheringi.----------------------.------- 116, 117

D

-__-_--_----_-_-__---__-_-__-- 115, 119

d'archiaci, Isocrinus...... ___________________________ 139

Delectopecten randolphi.............................. 141

randolphi tillamookensis. _________________________ 141

n. sp____________________________ 115, 119

Dentalium stramineum. ______________ ________________ 119

diegoana, Calyptraea... ______________________________ 119

Diplocrinus.------------------------------------- 121, 124

disjuncta, Thyasira.. ________________________________ 115

E

Echinophoria dalli— ____-_-___--__--___-__-__---_--__ 119 

"datfi var."_________.______--_______________ 115

rez______________________---_—————— 120

Endoxocrinus-.. __________________________________ 121, 124

Ennucula n. sp____-___-_-__----_---_-____---___-__- 119

Epitonium condoni----------------.--------------- 115, 118

keaseyense... ________________-_--______---___--- 115

(Boreoscala) condoni. ____________________________ 119

Eumorphocorystes naselensis.------------------------- 115

excavata, Lima (Acesta).----------------------------- 141

Exilia lincolnensis—--------------------------------- 119

P

Fimbria washingtoniana..-------------------------- 118, 119

Flabellum hertleini.------ _________________________ 115, 119

Fulgurofusus n. sp__________--___----___------_----- 119

G 

gabbi, Molopophorus—------------------------------- 118

Porterius—-—...—....,.......—.......— 115, 118, 119

gastaldi, Isocrinus..--------------------------------- 139

Pentacrinus------------------------------------ 139

"Gemmula" bentsonae____________________________ 115, 119

Geologic map-_--_--_------------------------------- 114

Glenotremites (Palaeantedon) caroliniana______________ 116, 117

Gyrineum jeffersonensis---------..------------- 115, 118, 119

H

haitiensis, Balanocrinus____________________________ 116, 117

hertleini, Flabellum—_____________-_-___--_---_--_- 115, 119

Himerometra bassleri_____________________________ 116, 117

holsaticus, Isocrinus-—______________________________ 135

hungaricus, Isocrinus-------------------------------- 139

Hypalocrinus—. _.____..„._. — — — — _ 121, 123, 124

iheringi, Cypelometra.----------------------------- 116, 117

Isocrinidae__-_--_----_-_------------------------- 121-122

Isocrinites pendulus ______________-_-__---__--------- 122

Isocrinus-..--...- — . __________ — - 117, 121, 122-124

californicus___________________________________ 140

crassitabulatus---------------------------------- 135

d'archiaci-------------------------------------- 139

gastaldi-. _________.__________--_--_._----------- 139

holsaticus-------------------------------------- 135

AMn^ancMS________-_-__-----__-_--------------- 139

knighti _________—________________---_--------- 134

nehalemensis.... 113,116,130,134, 135-139, 140, pis. 19-23

obtusus- ___________-_-_______------__---------- 117

145
146 INDEX

Isocrinus—Continued Page 

oreyonensis..-.--.--.-.----......-...--.------ 113, 116,

120, 184-1S5, 136, 138, 139, pis. 14-20, 22-24 

pendul us _ _____________________________________ 122

rotularis _______________________________________ 117

stellatus_____-____-__--____--_______________ 139, 140

tridactylus_ ___________________________________ 139

sp_____________________________________________ 115

Isognomon clarki-.--- _______________________________ 119

jeffersonensis, Gyrineum---...--...-----. .___-__ 115, 118, 119

johnsoni, Solemya (Acharax). ________________________ 141

K 

Keasey formation, columnar section___-____-__________ 115

lithology and paleontology_____---_-__-_____ .____ 118

map_ __________________________________________ 114

sedimentation _______-_____-_.-__-__-_-_______ 140-141

keaseyense, Epitonium. ______________________________ 115

kinkaidi, Spirotropis—.- _____________________________ 119

Knefastia washingtoniana ____________________________ 119

knighti, Isocrinus ___________________________________ 134

(Lamelliconchd) clarki, Pi<ar______-____-_--___________ 119

Lima (Acesta) ______________________________________ 141

excavata. ______________________________________ 141

oregonensis--.---.---.-..----.---.-.---.-.-... 115, 118

lincolnensis, Exilia. _________________________________ 119

lorenzanum, Nemocardium.--------- ____________ 115, 118, 119

M 

Macoma-- _________________________________________ 141

Macrocallista. ______________________________________ 141

Map, geologic, locality_________________.____________ 114

Metacrinus-- _____________________________________ 121, 124

Microcrinus conoideus _____________________________ 116, 117

Minor tnalletia- _____________________________________ 141

n. sp__________________________________________ 119

Molopophorus gabbi- ________________________________ 118

-- ________________________________________ 141

N 

naselensis, Eumorphocorystes---------.-.---....------- 115

Natica (Tectonatica) t0eafm'_____-__--_________ _______ 119

nehalemensis, Acila (Truncacila) ________________ 113, 118, 119

Isocrinus- _____________________________________ 113,

116, 130, 134, 1S5-1S9, 140, pis. 19-23 

Nekewis washingtonensis--.-------------------------- 119

n. sp__________________________________________ 115

Nemocardium lorenzanum. _____________________ 115, 118, 119

w>ecwen'______________________________________ 115, 118

Neocrinus- _______________________________________ 121, 124

nicoleti, Pew<acn°wws_________________________________ 135

Northwestern Oregon, geologic map___________________ 114

Nuculana washingtonensis- ___________________________ 119

O 

obliquum, /Smwm____________________________________ 119

obtusus, Pentacrinus--.-------.-...-.__.__---_______. 117

Pentacrinus [f= Isocrinus]... _____________________ 117

Olequahia schencki. ___________________________ 115, 118, 141

oregonensis, Lima (Acesta) _________________________ 115, 118

Isocrinus ______________________________________ 113,

116, 120, 124-135, 136, 138, 139, pis. 14-20, 22-24 

Organic evidence of environment _____________________ 141

OsJrea_____________________________________________ 141

Outcrops yielding crinoid re mains. _ ___________________ 120

r page

(Palaeantedori) caroliniana, Glenotremites...--------.. 116, 117

Paleoecology of Keasey crinoids_____________---_--_ 140-141

pendulus, Isocrinites...--------------- _______________ 122

Isocrinus __________________--__-,__-----------__ 122

Pentacrinus..-- ____________________________ 122, 123, 139

ariakensis--- ______________-_-_-___-------_---__ 139

bryani- ________________________________________ 117

gastaldi- ____________-_----__-_____-_-_--_-_-__- 139

nicoleti ___________________-_-_____--_--__------ 135

obtusus_____-______-_--_--_-__-_---_---_-----__ 117

rotularis ___-______-_---___-_--____--__-_-----__ 117

stellatus .. ________________________---_-----____ 139

whitei. ______________-_--_---___-_--__-__----_- 135

[?=/s0cn'nws] 06fwsws-_-_------__-_---------_~__ 117

rotularis ________________-____----_--_-_--__ 117

Pitar cZarfci_______________-_--__-_----__-_-------_- 115

(Lamelliconchd) clarki. __________________________ 119

Pittsburg Bluff formation, map_______________________ 114

Plant remains___-____-____-_--__------------_----__ pi. 22

Polynices n. sp-_-_____----__------__--__----------- 119

porterensis, Crenella. ____________--___-_------___-- 115, 119

Porterius gabbi........___________-____---__--- 115, 118, 119

(Portlandella) chehalisensis, Yoldia- ___________________ 119

Preparation of crinoid material____-___________- 116, 120-121

Propeamussium n. sp_____________--_____----_--_--__ 119

R

randolphi, Delectopecten.. ___________________------___ 141

tillamookensis, Delectopecten ______________________ 141

References-_ _______________________-__--__-----____ 142

rex, Echinophoria. __________________________________ 120

Rhizocrinus cylindricus________________--____-----__ 117

rotularis, Pentacrinus- _______________________________ 117

Pentacrinus [f =/s0mnws]-_________________-_____ 117

S

/SoramnMS_____-_____--______---____-----_---_-_- 121, 124

Scaphander stewarti________________________________ 119

Scappoose formation_______-_---___________-_----___. 114

schencki, Olequahia-.... _______________________ 115, 118, 141

Sedimentation at crinoid localities_________________ 140-141

Sinum obliquum.. ___________________________________ 119

Solemya willapaensis_______________________________ 115

(Acharax) johnsoni- _____________________________ 141

willapaensis-- ______________________________ 119

SoZen____________________________________________ 141

Spirotropis kinkaidi. ________________________________ 119

Spisula. ________________-__-____-___---_-_-_-_--__- 141

Springer, Frank, quoted.____________________________ 116

stellatus, Isocrinus.-------------------------------- 139, 140

Pentacrinus ____________________________________ 139

stewarti, Scaphander. ________________________________ 119

stramineum, Dentalium. _____________________________ 119

subbasaltiformis, Balanocrinus_____________________ 118, 123

(Tectonatica) weaveri, Natica... _______________________ 119

Teliocrinus. ________________________________________ 121

Tellina. ____________________-_--__-______--_--_-___ 141

n. sp_ —— — __- — ------ —-------- --------- 115,119

Thracia n. sp-_--____-___-_-___-__-__-___-_-_---_- 115, 118

Thyasira_________________________________________ 119

disjuncta_ _ ___________________________________ 115

n. sp___----__------------------------------_ 115, 118

tillamookensis, Delectopecten randolphi... _______________ 141

tridactylus, Isocrinus-------------.------------------ 139
INDEX 147

Page 

(Truncacila) nehalemensis, Acila. _______________ 113, 118, 119

Turcicula__________________________________________ 119

bairdii.... _____________________________________ 141

columbiana.--...........-----.----.----.----- 115, 118

n. sp_________-________________________________ 115

Turritella n. sp_____________________________________ 115

V 

Venericardia_____ __ _ ________________________________ 117

Vincentown sancL__________________-_______________ 117

Volcanic rocks, map ________________________________ 114

Volsetta—--- — -------- — ------- — ---- — -- — ---. 141

vulgaris, "Zan^opsis"_______________________________ 115

W 

washingtonianai F»m&ria_-____-____-______-________ 118, 119

Knefastia ______________________________________ 119

Page 

washingtonensis, Nekewis, ___________________________ 119

Nuculana- _____________________________________ 119

weaveri, Natica (!Tectonata'ca)___-____-_--_____-___-____ 119

Nemocardium_____________-_---__--_-_--____ 115, 118

whitei, Pentacrinus----.------------..-------.--.--.- 135

willapaensis, Soiewya_________________-_-_-___-______ 115

Solemya (Acharax) ______________________________ 119

Yoldia (Portlandella) chehalisensis.-. ______ ____________ 119

"Zanthopsis" vulgaris______________________________ 115

Zenometra conoideus. ________________________________ 117

PLATES 14-24
Plate 14

Isocrinus oregonensis Moore and Yokes, n. sp. Holotype (U.S.N.M. 560790), X 1, U.S.G.S. Tertiary loc. 15318. From Keasey 

formation, upper Eocene and lower Oligocene, Columbia County, Oreg. Compare with text fig. 29.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 233 PLATE 14

ISOCRINUS OREGONENSIS
Plate 15

Isocrinus oregonensis Moore and Vokes, n. sp. Cup and lower part of the crown; portion of the holotype (U.S.N.M. 560790), 

X 2.6, U.S.G.S. Tertiary loc. 15318. From Keasey formation, upper Eocene and lower Oligocene, Columbia County Oreg.
GEOLOGICAL SURVEY

PROFESSIONAL, PAPER 233 PLATE 15

ISOCRINUS OREGONENSIS
Plate 16

Isocrinus oregonensis Moore and Vokes, n. sp. Arms and pinnules, portion of the holotype (U.S.N.M. 560790). Covering plates of 

the pinnules are clearly visible in several areas, X 2.6. U.S.G.S. Tertiary loc. 15318. From Keasey formation, upper Eocene and 

lower Oligocene, Columbia County, Oreg.
GEOLOGICAL SURVEY

PROFESSIONAL PAPER 233 PLATE 16

FL^ *^<-£r"*»fo ^•L"^^.» ^BT'ifcL

ISOCRINUS OREGONENSIS
Plate 17

Isocrinus oregonensis Moore and Vokes, n. sp. Arms and pinnules, portion of ithe holotype (U.S.N.M. 560790), X 4.5 1, Portion 

of arms 5e and 5f (see text fig. 29); 2, portion of arms 4h, 5a-c. U.S.G.S. Tertiary loc. 15318. From Keasey formation, upper 

Eocene and lower Oligocene, Columbia County, Oreg.
GEOLOGICAL SURVEY

PROFESSIONAL PAPER 233 PLATE 17

ISOCRINUS OREGONENSIS
Plate 18

Isocrimis oregonensis Moore and Vokes, n. sp. Paratype (U.S.N.M. 560791 A), X 2.2, U.S.G.S. Tertiary loc. 15318. Compare with 

text fig. 31. From Keasey formation, upper Eocene and lower Oligocene, Columbia County, Oreg. This specimen is a mold 

prepared by removal of rotted calcite of the fossil by etching with hydrochloric acid.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 233 PLATE 18

ISOCRINUS OREGONENSIS
Plate 19

FIGURE 1. Isocrinus nehalemensis Moore and Vokes, n. sp., showing cup, proximal part of column, and lower part of arms, X 1.5,

paratype C (U.S.N.M. 560793C). Compare with text fig. 37.

2-5. Isocrinus oregonensis Moore and Yokes, n. sp. (2) Arm fragments of paratype E (specimen lost or misplaced), X 1.5; 

(3) distal surface of II Br3 of the half ray that bears arms E-H (text fig. 31) of paratype A (U.S.N.M. 560791 A), showing 

radially disposed fine crenellae of the syzygial articulation with II Br4, X 6.5; (4) paratype D (U.S.N.M. 560791D), 

showing arms and pinnules, X 1.5; (5) paratype E (specimen lost or misplaced), X 1.5. All specimens from Keasey formation, upper Eocene and lower Oligocene, Columbia County, Oreg., U.S.G.S. Tertiary loc. 15318.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 233 PLATE 19

^m "rti*" *&»

ISOCRINUS OREGONENSIS AND /. NEHALEMENSIS
Plate 20

[Figures X 3 natural size.]

FIGURES 1, 2. Isocrinus nehalemensis Moore and Yokes, n. sp. (1) Intact segment of column, 52 mm in length, showing regularly spaced 

nodals (distinguished by their slightly greater thickness and the presence of elliptical cirrus sockets at re-entrant 

angles), to some of which proximal portions of cirri are attached; two groups of the internodal columnals comprise 

eight columnals instead of the normal number of seven; paratype I (U.S.N.M. 5607931). (2) Small incomplete 

crown, showing dorsal cup, attached proximal part of the stem, and lower part of the arms; paratype G (U.S.N.M. 

560793G). Ray structure of this crinoid is shown in text fig. 21.

3. Isocrinus oregonensis Moore and Vokes, n. sp. Crown; the impression of the proximal columnal is seen at the base of 

the cup; ray structure of this crinoid is indicated in text fig. 33; paratype L (U.S.N.M. 560791L). All specimens 

from Keasey formation, upper Eocene and lower Oligocene, Columbia County, Oreg., U.S.G.S. Tertiary loc. 15318.
GEOLOGICAL SURVEY PKOFESSIONAI, PAPER 233 PLATE 20 tU'•.".•

*:. <*V - .« 

• -

**•••« * su :i

t£lS

AND /.
Plate 21

FIGURE 1. Outcrop of Keasey formation on Nehalem River, % mi south of junction of Oregon State Highways 47 and 202, near Mist,

Columbia County, Oreg., U.S.G.S. Tertiary loc. 15318.

2. Isocrinus nehalemensis Moore and Yokes, n. sp. Holotype specimen (U.S.N.M. 560792K), X 3. At right small regenerated arms belonging to one of the rays may be seen. Compare text fig. 38.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 233 PLATE 21

CRINOID LOCALITY NEAR MIST, OREG., AND ISOCRINUS NEHALEMENSIS
Plate 22

FIGURE 1. Isocrinus nehalemensis Moore and Vokes, n. sp. Paratype J (U.S.N.M. 560793J), which includes an unusually long 

attached part of the stem, X 3. Nodals are closely spaced near the dorsal cup, and whorls of short, upwardly directed 

cirri are very numerous. All columnals are thinner in the vicinity of cup than in middle and lower parts of stem. 

U.S.G.S. Tertiary loc. 15318.

2. Two carbonized leaves of plants found in association with the crinoid remains at U.S.G.S. Tertiary loc. 15318, X 1.5.

3. Isocrinus oregonensis Moore and Vokes, n. sp. University of California Museum of Paleontology paratype A5018C3, X 3, 

Keasey formation on Nehalem River near Mist, Oregon; a stem fragment consisting of many articulated columnals, 

each of the regularly spaced nodals bearing a whorl of five long slender cirri.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 233 PLATE 22

1 3

ISOCRINUS NEHALEMENSIS, I. OREGONENSIS, AND ASSOCIATED PLANT REMAINS
Plate 23

FIGURES 1-3, 5, 6, 8-10. Isocrinus oregonensis Moore and Vokes, n. sp. (1) Proximal face of nodal of large stem, showing short crenellae of the pentameres, the inner ones located very close to the axial lumen; proximal cirrals are attached to the nodal at three 

re-entrants; paratype (U.S.N.M. 560903A), X 4.5. (2) Distal face of internodal, showing type of articular surface that is in 

contact with the proximal face of a nodal, as illustrated in fig. 1; X 4.5. (3) Side view of relatively large stem segment consisting of a nodal (lowermost columnal) and seven internodals that are alternating small and large; the topmost internodal is a 

hypozygal columnal, belonging next below a nodal and characterized by a smooth articular surface proximally where it joins 

the nodal; the elliptical facets for attachment of two cirri are well defined on the nodal; paratype (U.S.N.M. 560903A), X 4.5, 

(5) Proximal face of a strongly stellate internodal; paratype (U.S.N.M. 560903B), X 8. (6) Distal face of an internodal; paratype (U.S.N.M. 560903C), X 8. (8) Proximal face of an internodal having very strongly marked crenellae; paratype (560903B) 

X 8. (9) Side view of portion of a medium-sized stem showing two nodals, which are distinguished by their greater thickness 

and cirrus sockets in re-entrants on the side, and alternating large and small internodals; the larger internodals are distinguished 

by the angulated nature of their outer surface, which gives them a keeled appearance; points of the star-shaped columnals tend 

to be produced in the form of a rounded boss; paratype (U.S.N.M. 560903C), X 8. (10) Proximal face of a nodal, showing gently 

concave nature of each pentamere and relatively coarse short crenellae; paratype (U.S.N.M. 560903C), X 8.

4,7,11. Isocrinus nekalemensis Moore and Vokes, n. sp. (4) Distal face of a nodal, showing nearly featureless smooth surface 

that adjoins the hypozygal internodal and facilitates parting of the stem at this articulation; cirrus sockets are partly visible, 

andatright upper is an attached cirral segment; paratype (U.S.N.M. 560904B). (7) Proximal face of an internodal, showing strong 

crenellae; paratype (U.S.N.M. 560904A). (11) Side view of portion of stem showing three nodals and three groups of internodals, 

each consisting of seven columnals of nearly uniform size; paratypes (U.S.N.M. 560904A, B). All figures X 8.

All specimens from Keasey formation, upper Eocene and lower Oligocene, of Oregon. Figs. 1-3 from U.S.G.S. Tertiary loc. 15282, 

Columbia County; figs. 5, 6, 8-10 from U.S.G.S. Tertiary loc. 15508, figs. 4, 7, 11 from U.S.G.S. Tertiary loc. 15268, Columbia 

County.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 233 PLATE 23

X 8

ISOCRINUS COLTJMNALS
Plate 24

All illustrated specimens are from the Keasey formation at the locality on Nehalem River near Mist, Oregon, University of California loc. A5018 (same as U.S.G.S. Tertiary loc. 15318).

FIGURE 1. Isocrinus oregonensis Moore and Vokes, n. sp., University of California Museum of Paleontology, paratype no. A5018B, 

X4, side view of dorsal cup and proximal part of arms.

2. Same, paratype no. A5018C1, X4, side view of dorsal cup and proximal part of arms; a few columnals are attached to 

the cup.

3. Same, paratype no. A5018B, X 4, base of dorsal cup, showing subhorizontal proximal extension of radial plates, which 

occupy re-entrants between points of the strongly stellate columnals; broken distal parts of the basal plates occur at 

extremities of the points of the columnals.

4. Same, paratype no. A5018A, X 2, a crown consisting of a complete dorsal cup and lower parts of most of the rays.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 233 PLATE 24

ISOCRINUS OREGONENSIS

Shorter Contributions 

to General Geology 

19504951

This professional paper was printed 

as chapters ^4—E9 inclusive

P A P E R 233

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1953
I

UNITED STATES DEPARTMENT OF THE INTERIOR 

Oscar L. Chapman, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director
CONTENTS

[The letters in parentheses preceding the titles are those used to designate the papers for separate publication]

Page

(A) Fresh-water mollusks of Cretaceous age from Montana and Wyoming, by Teng-Chien Yen (published in December 1951)_ 1

(B) Molluscan fauna of the Morrison formation, by Teng-Chien Yen (published in February 1952)____________________ 21

(C) Upper Silurian brachiopods from southeastern Alaska, by Edwin Kirk and Thomas W. Amsden (published in April 1952)__ 53

(D) Devonian and Mississippian rocks of central Arizona, by John W. Huddle and Ernest Dobrovolny (published in February 1952)____________________________________________________________J______ 67 

(E) Lower Tertiary crinoids from northwestern Oregon, by Raymond C. Moore and Harold E. Yokes (published in March

____________-__________________________________________________________________________________ 113

ILLUSTRATIONS

PLATE 1. Fossil and Recent fresh-water mollusks___--_--____________________________-_-__--------_________ Following 20

2. Upper Cretaceous nonmarine mollusks___-_____________________________________--------__--___-__ Following 20

3, 4. Unio and Vetulonaia. __________________________________________________________________________ Following 52

5. Unio and jHadrodon_____________________________________________________________________________ Following 52

6. Gastropoda^___________________________________________________________________________________ Following 52

7. Atrypella, Lissatrypa, Nucleospira, Alaskospira, Howellella, and Defa%ris_______________________________ Following 66

8. Camarotoechia, Atrypa Atrypella, and Conchidium,. ________________________<l________________-__-_ Following 66

9. Conchidium alaskense________________________________________________________________________ Following 66

10. Conchidium, Camarotoechia, Eospirifer, Howellella, and Cymostrophia- ______________________________ Following 66

11. Columnar sections along line A-A' from the East Verde River to the Black River, central Arizona__________ In pocket

12. Columnar sections along line B-B' from Tornado Peak, central Arizona, to Cedar Mesa, Utah______________ In pocket

13. Map showing the thickness and facies of the Martin formation in Gila and adjacent counties, Ariz___________ In pocket

14-18. Isocrinus oregonensis. __________________________________________________________________ Following 146

19, 20. Isocrinus oregonensis and /. nehalemensis___________________________________________________ Following 146

21. Crinoid locality near Mist, Oreg., and Isocrinus nehalemensis________________________________________ Following 146

22. Isocrinus nehalemensis, I. oregonensis, and associated plant remains __________________________________ Following 146

23. Isocrinus columnals from the Keasey formation, Oregon.__________________________________________ Following 146

24. Isocrinus oregonensis______________________________________________________________________ Following 146

FIGURE 1. Map showing localities of Morrison invertebratecollections_____________-_______---_---__-______________ 29

2. Serial sections of Camarotoechia reesidei, n. sp_______________________________-__---------_-----_-------- 57

3. Serial sections of Atrypella sc/ie«Y__________________________________________-__------_-_--_--_-__------- 58

4. Serial sections of Lissatrypa aetheroidea. _____________________________________________________________ 59

5. Serial sections of Atrypella tennis, n. sp_______________________________________--------_-------__------- 60

6. Serial sections of Atrypella borealis, n. sp__________________________________________________________ 60

7. Serial sections of Alaskospira duribari, n. sp______________________________ — __________ — — __ — _____ 62

8. Map showing the distribution of outcrops of Devonian and Mississippian sedimentary rocks in Arizona————_ 69

9. Index map of northeastern Arizona________________________________________________________________ 70

10. Pre-Devonian rocks of central Arizona________________________________________________________ — _____ 72

11. Generalized section of the Martin formation in central Arizona________________________ — — — ______ — _____ 73

12. View of the Devonian and Mississippian rocks exposed in the Salt River Canyon, central Arizona— — _ — _____ 74

13. Lower member of the Martin formation as exposed in a road cut on United States Highway no. 60, central Arizona. 75

14. Diagrammatic sketch of the exposures in Cow Canyon, central Arizona-__________________________________ 77

15. Geologic sketch map of the Cliff House Canyon area, central Arizona___________________________________ 78

16. Diagrammatic sketch of the Martin formation, near Cliff House Canyon____________ — _____________________ 79

17. Map showing distribution of Late Devonian paleogeographic elements in Arizona__-__--_- — ________________ 80

18. Diagrammatic section across Pine Creek at Natural Bridge, northwest of Payson, Arizona.___________ — — ___ 81

19. Contact between the Martin formation and the Redwall limestone in Flying "V" Canyon, central Arizona.____ 81

20. Contact between the Redwall limestone and the basal members of the Naco formation on United States Highway

no. 60, central Arizona________________________________________________ — ___________________ — _ 87

21. Contact of the Redwall limestone and the Naco formation near the confluence of Horton and Tonto Creeks, Gila

County, Arizona._________________________________________________________—___________________ 88

22. Cave fillings in the Redwall limestone on United States Highway no. 60, central Arizona——_________________ 89

23. Rubble breccia in the Redwall limestone on United States Highway no. 60, central Arizona.____ — ________ — _ 89

24. Chert breccia in the base of the Naco formation, central Arizona_____________________ — — _______________ 90

25. Restored section across the northern part of Mazatzal land at the end of Mississippian deposition._ — _________ 91

ni
IV CONTENTS

Page

FIGURE 26. Early Mississippian paleogeography of the southwestern United States________________________________ 91

27. Map of upper Nehalem basin, northwestern Oregon, showing crinoid localities __________________________ __ 114

28. Columnar section of the Keasey formation.____________________________________________________________ 115

29. Holotype of Isocrinus oregonensis--, _______________________________________________________________ 125

30. Paratype A of Isocrinus oregronensts________________________________--_--_______-------__-__________ 126

31. Ray structure of paratype A of Isocrinus oregonensis--------------------------------------- ----------- 126

32. Paratype B of Isocrinus oregonensis and diagram of ray structure___________________________________ 127

33. Ray structure of paratype L of Isocrinus oregonensis_____________________________________________ — — ___ 129

34. Brachials and pinnules of the holotype of Isocrinus oregonensis___ ______________________________ — _. — _____ 132

35. Paratypes of Isocrinus oregonensis in collections of the University of California Museum of Paleontology_____ 133

36. Isocrinus columnals_ ______________________________________________________________________________ 133

37. Paratype C of Isocrinus ne/iaZemerms___________________________________________----_-----_-_-----_-__ 136

38. Ray structure of holotype and two paratypes of Isocrinus nehalemensis __________________________________ 137

39. Radial plates and syzygial articulation of Isocrinus nehalemensis and cirrus socket of 7. oregonensis- ___________ 138