Cretaceous Plants 

from Southwestern 

Colorado

GEOLOGICAL SURVEY PROFESSIONAL PAPER 221-D

>
Cretaceous Plants 

from Southwestern 

Colorado

By ROLAND W. BROWN

SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1949, PAGES 45-66

GEOLOGICAL SURVEY PROFESSIONAL PAPER 221-D

A study of fossil plants useful in determining 

the probable boundary between the Lower and 

Upper Cretaceous deposits

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1950
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 20 cents (paper cover)
CONTENTS

Page

Abstract-_____________________________________________________________________________________________________ 45

Geological background. ________________________________________________________________________________________ 45

Age and significance of the fossil plants_________________________________________________________________________ 47

Systematic descriptions..,-_____________________________________________________________________________________ 48

Specimens of uncertain identity________________________________________________________________________________ 52

Bibliography- _________________________________________________________________________________________________ 53

Index._____________________________________________________________________________________________________ 65

ILLUSTRATIONS

Page 

Plates 9-12. Cretaceous plants. ._-_-----___---_-___-_-___-_-_-__.._-__---_.-___---_-______-_.__-_____________ 55-63

in

CRETACEOUS PLANTS FROM SOUTHWESTERN COLORADO

By ROLAND W. BROWN

ABSTRACT

In southwestern Colorado a sequence of strata between the Jurassic carnotite-bearing Morrison formation (fMcElmo) and the Upper Cretaceous marine 

Mancos shale contains fossil plants that are described 

here and used for determining the most likely position 

of the Lower Cretaceous-Upper Cretaceous boundary. 

The plants fall into two groups, the older, with the 

conifer Frenelopsis varians Fontaine, indicating Lower 

Cretaceous age, and the younger, with numerous ferns 

and well-developed dicotyledons, characterizing the 

early Upper Cretaceous. The boundary is probably at 

the top of the unit that Coffin called fPost-McElmo 

and at the base of his overlying Dakota.

GEOLOGICAL BACKGROUND

Investigation during the past 30 years of the carnotite-bearing sedimentary rocks of the fMcElmo (now 

Morrison) formation of southwestern Colorado and 

adjacent areas in Utah has resulted in the collection of 

plants from different horizons in the strata above the 

fMcElmo formation and beneath the Mancos shale. As 

the fMcElmo is considered, for the most part at least, 

to be of Jurassic age and equivalent to the Morrison 

of other regions, and as its uppermost beds are separated from the overlying plant-bearing strata by an 

unconformity of unknown extent, and as marine beds 

of the Mancos shale of Upper Cretaceous age conformably overlie the plant-bearing beds, it follows that all 

of Lower Cretaceous (unless some of the uppermost 

part of the fMcElmo is Lower Cretaceous in age) and 

part of Upper Cretaceous time must be represented by 

the interval between the fMcElmo and Mancos deposits. 

How much, if any, of this sequence is Lower Cretaceous 

and how much is Upper Cretaceous is the problem 

posed for solution by a study of the fossil plants.

The best collections of plants have come from southwestern Colorado, and this area, therefore, will receive 

most attention here. A complete description of the

tlndicates the name has been abandoned or rejected for use 

in classification in Geological Survey publications.

area, with maps and geologic sections, was published 

by R. C. Coffin (1921) and further data and opinions 

concerning ages and correlations were published by 

W. L. Stokes (1944, 1948). Generalized from Coffin 

and in his nomenclature, a composite geologic section 

southwest of Nucla, Colo., includes the following sequence of strata in descending order.

Geologic section near Nucla, Colo.

Mancos shale. Dark JJpper Cretaceous marine shales with 

QrypUaea newberryi. These lie comformably on the Dakota 

sandstone.

Dakota sandstone. Sandstone, shale, coal (some rninable), 

100-200 feet of basal conglomeratic sandstone. Plants.

f Post-McEHmo. Green to purple or somewhat varicolored shale, 

sandstone, limestone, dark shale, 100-200 feet of basal conglomeratic sandstone. Plants. The basal conglomerate, 

like that at the base of the Dakota, is a cliff-maker, and the 

two may readily be confused under given circumstances. 

This conglomerate lies on an undulating fMcElmo surface. 

At one locality, according to Coffin (1921, p. 112), Halymenites was found in the sandstone not far above the 

fMcElmo-fPost-McElmo contact, thus indicating a temporary interruption of fresh- by brackish-water or marine 

conditions. This fPost-McElmo unit was named Burro 

Canyon formation by Stokes in 1948.

fMcElmo formation. The upper part is chiefly variegated shale, 

whereas the lower part is white to greenish-gray sandstone 

that contains the carnotite-bearing beds. Fossil wood, 

poorly preserved twigs, and other plant fragments occur 

throughout the formation. Large reptilian bones occur in 

the basal portion. Coffin designated the fMcElmo as 

Jurassic or Cretaceous. The U. S. Geological Survey 

regards it as Morrison (Jurassic).

The fPost-McElmo and Dakota of the foregoing section are the debatable strata whose age is in question. 

Because only plant fossils have been obtained from 

them, the history of attempts to determine their age 

is that of the treatment of the several collections, as, in 

part, already related by Junius Henderson (Coffin, 1921, 

pp. 113-118.) Of these collections, the first to be reported was made in 1915 by J. T. Duce for the Geological 

Survey of Colorado. This came from the upper sandy 

beds of the Dakota and was studied by Cockerell (1916), 

who tentatively identified in it the following species

45
46 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1949

(with later emendations suggested by E. W. Berry, in 

parentheses) :

Equisetum (=stipe of Matonidium americanum) 

Matonidium althausi (=Matonidium americanum) 

Fragments of other ferns (1=Onychiopsis) 

Cycadospadix? (=frond base of Matonidium americanum) 

Sapindopsis (= undetermined dicotyledon)

Cockerell considered that this assemblage indicated 

Lower Cretaceous age, probably the same as the Fuson 

shale in the vicinity of the Black Hills, S. Dak., and 

somewhat younger than the Kootenai formation of 

Montana.

In 1914 Henderson and others collected plants from 

a black shale horizon south of Nucla, but these were 

not seen or considered by Cockerell at the time he reported the 1915 collection by Duce. They were, however, sent to E. W. Berry early in 1919 along with the 

Duce material. Berry (1919) shortly thereafter published a paper dealing with the principal and most 

striking species in the Duce collection, namely, the 

fern Matonidiiim americanum. His opening statement, 

unfortunately, is misleading, for it says that "In 1916 

Professor Cockerell, of the University of Colorado, 

published a brief note based upon plant material collected from the supposed McElmo formation of southwestern Colorado." Reference to Cockerell's opening 

paragraph (1916, p. 109), however, shows that Berry 

misread the locality citation, which says in part, "Above 

the McElmo, black shales alternate with massive sandstone, the two combined including the uppermost 131 

feet of the whole exposure. The plants are preserved 

in hard white quartzose sandstone, with occasional iron 

concretions about 10 feet below the top of the section." 

In this paper Berry did not express a definite opinion as 

to the age of the collections. Concerning the stratigraphic level of the black shale, Henderson said (Coffin, 

1921, p. 116) that it was "in a shale lens in the basal 

conglomerate of the so-called Dakota, near the top of 

Norwood Hill, where the wagon road from Placerville 

to Norwood leaves the San Miguel Canyon." Henderson's use of the term "so-called Dakota" would superficially suggest the Dakota of Coffin, but, in reality, the 

black shale is in the basal part of the f Post-McElmo as 

a letter, dated Feb. 1, 1919, from Henderson to Berry 

indicates:

The material from the black shale, . . . occurred in a lens 

of shale in the basal conglomerate, just above the variegated 

shales of the McElmo, far below the upper sandstone. . . . 

Since the question of the position of this shale was raised by 

the discovery of the material in the upper sandstone, Mr. Worcester, who is a very careful observer, revisited the place, and 

fully confirms my notes.

Berry (Coffin, 1921, p. 116) identified the following 

species in the black shale:

BracJiyphyllum sp.

Pinus susguaensis Dawson

Splienolepis Jcurriana (Dunker) Schenk

Cissites sp.

Sassafras mudgei Lesquereux

Berry's opinion (Coffin, 1921, p. 117) concerning the 

age of both collections, that in the upper sandstone and 

that in the black shale, is as follows:

Regarding the age of the material, it is not extensive or good 

enough for one to be dogmatic about, but I see nothing to indicate that either the older shale or the younger sandstone represents the true Dakota. There are no typical Dakota species 

in either and the general facies appears to me to be slightly 

older. Neither would I place either in the Lower Cretaceous, 

hut would be inclined to consider that both floras represent the 

same general horizon, and I am strongly of the opinion that this 

horizon is to be correlated with what has been called the Purgatoire formation in southeastern Colorado. . . . It is also to be 

correlated with the Belvidere section of southern Kansas at the 

top of the Washita division of the Texas Comanchean. The 

Washita is commonly considered to represent the top of the 

Lower Cretaceous, but I am confident that it is Cenomanian in 

age and represents the lower part of the Upper Cretaceous as I 

stated in my "Upper Cretaceous Floras of the World", and in 

this I am corroborated by European paleontologists from the 

fauual evidence.

Thus the matter stood until 1925, when W. W. Boyer 

found fragmentary plants in the Dakota at the Liberty 

Bell mine near Naturita, south of Nucla. These were 

identified in a routine report, by F. H. Knowlton, as 

including the species:

Cladophlebis falcata montanensis Fontaine 

Gleichenia nordenskioldi Heer

Of the age Knowlton said: "It may be Dakota, but 

somehow I cannot escape the conviction that it is older 

than Dakota."

In 1944 W. L. Stokes, associated with K. P. Fischer 

of the U. S. Geological Survey, obtained an excellent 

collection from gray shales in the Dakota at an abandoned coal mine in SW^SE^ sec. 11, T. 46 N., K. 16 W. 

In 1945 he found a good specimen of Frenelopsis varians 

Fontaine in black shale in the upper part of the f PostMcElmo, one-half mile east-southeast of the junction 

of Disappointment Creek and Dolores River. He also 

found a fragment of a cycadeoid in the basal fPostMcElmo on the southwest side of Little Gypsum Valley. 

From sandstone in the Dakota near the black shale locality, but about 20 feet higher stratigraphically, he 

obtained a collection containing numerous dicotyledonous leaves. Finally, in 1948, he made another excellent collection in pinkish-gray shale of the Dakota 

near the coke ovens at Naturita. This collection con-
CRETACEOUS PLANTS FROM SOUTHWESTERN COLORADO 47

tains the same ferns as occur in his original 1944 

collection but also includes several well-preserved 

dicotyledons.

The best material of each recognizable species in all 

these collections, now available to me, is here illustrated 

and described, and an attempt is made to integrate all 

the information into a satisfactory picture of the entire 

situation.

AGE AND SIGNIFICANCE OF THE FOSSIL PLANTS

The fossil plants here described fall into two groups. 

The first includes Cycadeoidea sp. (pi. 9, fig. 13), 

Brachyphyllum crassicaule Fontaine (pi. 9, figs. 5, 6), 

Frenelopsis varians Fontaine (pi. 9, fig. 12), SphenoUpis hurriana (Dunker) Schenk (pi. 9, fig. 14), and 

a few undetermined specimens (pi. 9, figs. 8-11). 

The second group contains all the remaining specimens, including numerous ferns and well-developed 

dicotyledons.

Three of the specifically identified species of the first 

group, but particularly Frenelopsis varians, are characteristic Lower Cretaceous forms. Cycadeoidea falls 

readily into this picture. Frenelopsis varians, however, is the clue to the age of this group, as it has never 

been found in younger strata. All the specimens in 

this group occur in the fPost-McElmo of Coffin (p. 3) 

and beneath the conglomeratic sandstone of the Dakota, 

above which all the plants of the second group were 

collected.

The plants of the second group include chieflly species 

that occur in the large flora described by Lesquereux, 

Newberry, and others from the brownish Dakota sandstone of Kansas and Nebraska, in the Woodbine formation of Texas, the Dakota of the Black Hills, S. Dak., 

and the Upper Cretaceous rocks of Greenland. A few 

species were probably closely related to some in the 

Patapsco formation of the Potomac group in the Atlantic Coastal Plain.

In view of these facts I conclude that in southwestern 

Colorado the fPost-McElmo is Lower Cretaceous and 

the Dakota of Coffin is Upper Cretaceous. I would 

draw the boundary line at the bottom of the conglomeratic sandstone at the base of Coffin's Dakota.

The scarcity of well-preserved plants in the Lower 

Cretaceous section in southwestern Colorado is matched 

by a similar condition east of the Eocky Mountains in 

the vicinity of Morrison and Walsenburg, Colo. Stose 

(1912, p. 3) described the typical Purgatoire formation 

in the Apishapa quadrangle east of Walsenburg, Colo., 

as including 220 feet of beds, chiefly sandstone in the 

basal portion and coal, shale, and sandstone in the 

upper portion, the whole lying conformably between

variegated Morrison (Jurassic) and massive Dakota 

sandstone (Upper Cretaceous). The age of the 

Purgatoire was determined as Comanche (Lower 

Cretaceous) by Stanton on the evidence of characteristic marine invertebrates and fishes. Gryphaea corrugata, in particular, was said to indicate equivalence 

of at least part of these beds with the Kiowa shale of 

Kansas. No plants have been taken from the type area 

of the Purgatoire formation, but some poorly preserved 

leaves were collected by W. T. Lee in beds so designated 

by him at the type section of the Morrison formation 

near Morrison, Colo. These plants were identified 

by F. H. Knowlton and restudied by E. W. Berry 

(Brown, 1946, p. 240), with rather inconclusive results, 

except that the flora resembles that from the Cheyenne 

sandstone of Kansas.

The only forms in common between the fPostMcElmo and the Kootenai formation of Montana are 

Sphenolepis kwriana (Dunker) Schenk and the problematic Finite susquaensis Dawson.

An interesting situation has arisen in regard to the 

Potomac group of the Atlantic Coastal Plain, which 

has long been regarded as Lower Cretaceous. In the 

volume, edited by Anderson (1948, pp 126-151), on 

the subsurface geology in three deep wells, H. E. Vokes 

discusses the Mollusca found at depths 4,875 to 4,885 in 

the Maryland Esso No. 1 well, 4^ miles north of 

Ocean City, Md. Vokes inclines to the belief that the 

Patuxent formation is Lower Cretaceous and the 

Arundel and Patapsco formations are earliest Upper 

Cretaceous, for he finds that the Mollusca of the two 

latter formations have their closest affinities with those 

of the Woodbine formation (Upper Cretaceous) of 

Texas. This conclusion appears to be fortified by C. 

W. Gilmore's opinion that the dinosaurs of the Arundel 

formation have closest affinities with those of the Belly 

River formation (Upper Cretaceous) in Canada. The 

great development of dicotyledons in Patapsco time, 

and especially of species similar to, if not identical with, 

some in the Dakota sandstone and other Upper Cretaceous formations of the western interior, lends considerable weight to the view that the Patapsco, at least, 

should be removed from the Lower Cretaceous 

classification.

Not much can be inferred from the fossil plants concerning the climate and environment of southwestern 

Colorado during Lower Cretaceous and early Upper 

Cretaceous time. The probability is that the region 

was low lying and not far above sea level. Frenelopsis 

varians, as judged by its occurrence in the Trinity 

group of Texas where it is found with marine inverte-
48 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1949

brates, preferred a coastal environment. Cycadeoidea 

may indicate a somewhat drier location on a hillside.

The early Lower Cretaceous sediments in this area 

were deposited near sea level, because at one locality 

Halymenites has been found. The ferns Matonidium 

and Bolbitis, if judged by their modern relatives in the 

Malay region, would indicate a relatively warm and 

moist environment at the beginning of the Upper 

Cretaceous. These ferns, however, were found in the 

shales associated with coal beds and reflect a swampy 

condition. The dicotyledons, on the other hand, indicate drier situations probably not far from the coalforming swamps.

SYSTEMATIC DESCRIPTIONS

ASPLENIACEAE 

Asplenium sp.

Plate 10, figure 4

Asplenium, dicksonianum Heer. Ward, U. S. Geol. Survey 19th 

Ann. Kept., pt. 2, p. 704, pi. 170, fig. 1,1899.

The specimen figured here appears to agree in every 

respect with that reported by Ward from the basal beds 

of the Dakota sandstone in Evans quarry, 5 miles 

southeast of Hot Springs, S. Dak. This fern was evidently bipinnate, with the pinnules in some instances 

deeply cut. These lobes have entire margins. The 

venation is open and once or twice forked. No fertile 

fronds have been seen..

It does not seem to me that either the present specimen or Ward's specimen from the Black Hills should 

be referred to Heer's Asplenium dicksonianum, which, 

according to the figured type and other supplementary 

specimens, is a smaller, more delicate fern, although 

perhaps of the same genus. There is doubtless confusion in regard to the generic assignment, as somewhat 

similar or perhaps identical material has been referred 

to Onychiopsis, Aneimia, and other genera. I know of 

no method to resolve this difficulty until adequate fertile 

material is found.

Occurrence: Abandoned coal mine near Naturita, 4 

miles south of Nucla, Colo. Collected by W. L. Stokes, 

1944.

GLEICHENIACEAE 

Gleichenia kurriana Heer

Plate 10, figures 5, 6

Gleichenia kurriana Heer. Lesquereux, U. S. Geol. Survey Terr. 

Kept., vol. 6, p. 47, pi. 1, figs. 5, 5b, 5c, 1874.

Many species of Cretaceous gleichenias have been described, especially by Oswald Heer from Greenland. 

The Greenland species were reviewed by A. C. Seward,

who resurrected the Paleozoic name Gleichenites for the 

few species to which he reduced the many described by 

Heer.

As the specimens under consideration here bear no 

sori, they can be compared but probably not identified 

satisfactorily with any described species. They resemble closely some specimens of Gleichenites giesekiana (Heer) Seward, .as synonymized by Seward 

(1926, p. 69). They are somewhat like Gleichenia argentinica Berry (1924, p. 17). However, no matter 

how these comparisons may be evaluated, the species 

is very likely that identified as Gleichenia kurriana 

Heer by Lesquereux from the Dakota sandstone, 3 miles 

east of Fort Harker (now Kanopolis), Kans. Lesquereux was uncertain that the Dakota species is identical 

with G. kurriana from Europe.

That the Gleichenia represented by the Colorado 

specimens has a long chronological range is likely, for 

Heer's Lower Cretaceous species seem to range locally 

also into the Upper Cretaceous.

A small fragment of what appears to be this species 

was collected by Karl Waage in 1943 from a white sandstone in the Dakota near Stone City, 15 miles northwest of Pueblo, Colo.

Occurrence: One and one-half miles southwest of 

coke ovens, Montrose County, Colo. Collected by W. L. 

Stokes, 1948.

MATONIACEAE 

Matonidium americanum Berry

Plate 10, figures 7, 8

Matonidium americanum Berry, Torrey Bot. Club Bull., vol.

46, p. 287, fig. 2; pi. 12, figs. 1-12; pi. 13, figs. 3-6, 1919. 

Matonidium althausi (Dunker) Ward. Cockerell, Washington

Acad. Sci. Jour., vol. 6, p. Ill, fig. 2,1916. 

Cycadospadix? sp. Cockerell, idem, p. 110, fig. 1.

This species was as well described by Berry as was 

possible with the fossil material at his disposal. To 

that description need be added perhaps only a few minor 

details. The venation of the fertile pinnules is obscure, 

but that of the sterile pinnules is as shown in figure 7. 

The secondary veins may be simple, branched, with a 

few scattered anastomoses, the principal forming lateral 

areolations along the midribs.

The features that distinguish this species from the 

Lower Cretaceous Matonidium althausi (Dunker) 

Ward are: more numerous pinnae, shorter and broader 

pinnules, fewer sori, and more conspicuously scorpioid 

disposition of the pinnae at the top of the stipe. As no 

exactly identical material has been described before, the 

presumption is that M. americanum represents an advance on M. althausi. This inference is strengthened 

by the fact that in the present material are fragments,
CRETACEOUS PLANTS FROM SOUTHWESTERN COLORADO 49

such as relatively long, slender pinnules completely 

covered with sori, that suggest throwbacks to M. 

althausi.

An Upper Cretaceous species comparable to Matonidium americanum is Matonia wiesneri Krasser (1896, 

p. 119, pi. 11, fig. al; pi. 12, figs. 1, 2; pi. 17, fig. 10) 

from Cenomanian beds near Kunstadt, Austria. 

Krasser's illustrations, showing the habit of the species, 

suggest a peltate arrangement of pinnae around the 

apex of the stipe, but I suspect that the drawings perhaps do not represent the specimens adequately on this 

point and that the pinnae are actually disposed in a 

rather close scorpioid fashion fanwise, as stated in 

Krasser's description. According to Krasser's figures, 

the venation of the pinnules is without anastomoses or 

areolations. Such fruiting specimens as Krasser found 

had few sori per pinnule. Despite these close similarities, I am disinclined to recognize the two species 

as identical.

Matonidiwn americankm resembled the graceful, existing Matonia pectinata Robert Brown, of southeastern 

Asia and the East Indies. This species has a creeping 

rhizome that produces at distant intervals simple, unbranched fronds composed of a tall, upright stipe, the 

apex of which widens into a semicircular base or crown, 

giving rise dichotomously to the scorpioidly disposed 

pinnae, which spread out horizontally, that is, at right 

angles to the stipe.

Occurrence: At abandoned coal mine near Naturita, 

4 miles south of Nucla, and at coke ovens, Montrose 

County, Colo. Collected by W. L. Stokes.

POLYPODIACEAE 

Bolbitis coloradica Brown, n. sp.

Plate 12, figures 6,. 7

Sterile frond pinnate below, but with segments tending to coalesce into a lobed blade toward the apex. 

Margin entire. Basal pinnae linear lanceolate, sessile 

or nearly so, with slightly asymmetric rounded bases. 

Secondary veins numerous, closely spaced, slightly 

curved, almost at right angles to the midrib, simple until near the margin, where they may fork or branch. 

Areoles between the secondary veins somewhat rhomboidal and elongated parallel to the secondaries.

Fertile fronds not present in the collection.

Comparison of these fossils with living ferns reveals 

closest resemblance to the entire-margined species of 

Bolbitis, formerly variously called Campiwm, Poecilopteris, Heteronewron, and others. The genus comprises about 85 species, distributed in the tropics, 

particularly of Africa and the Indo-Malayan region.

868180 50 2

Occurrence: At the abandoned coal mine near 

Naturita, Colo.

PTERIDACEAE 

Llavea hesperia Brown, n. sp.

Plate 11, figure 6

This somewhat eroded sterile leaf is nevertheless well 

enough preserved to indicate its original cordate outline. The veins are open, closely spaced, and repeatedly 

forked. The margin is minutely dentate.

At least three living species of ferns may be considered for comparisons with the fossil. Humata 

ophioglossoides Cavanilles, a davallioid fern from the 

Malay-Polynesian region, is an epiphyte with simple, 

lanceolate-cordate, sterile fronds that are about the 

same size as the fossil. The veins, however, are thicker 

and less forked. Pellaea cardiomorpha Weatherby, 

from Mexico, is a pinnate pteridoid fern with cordate 

pinnules closely simulating the fossil. It, however, 

prefers relatively dry, rocky situations, whereas the 

fossil, judging from its associates, lived in a moister 

habitat. Llavea cordifolia Lagasca, a monotypic 

pteridoid fern from central Mexico to Guatemala and 

distantly related to Pellaea cardiomorpha, has cordate 

pinnules and seems to compare best of all with the 

fossil. The assignment of the fossil to Llavea must 

be considered tentative until a fertile pinnule or other 

confirmatory material is found.

For making available material of living ferns and 

for helpful consultation toward identification, I am 

grateful to C. V. Morton, curator of ferns in the U. S. 

National Herbarium, Smithsonian Institution.

Occurrence: One and one-half miles southwest of 

coke ovens, Montrose County, Colo.

TEMPSKYACEAE 

Tempskya knowltoni Seward

Plate 9, figure 15

Tempskya Icnowltoni Seward, Annals of Botany, vol. 38, pp. 

485-507, pis. 16, 17, 1924; Brown, Washington Acad. Sci. 

Jour., vol. 26, pp. 46, 47, fig. 5, 1936; Read and Brown, U. S. 

Geol. Survey Prof. Paper 186, pp. 112-114, pi. 29, figs. 1-3, 

1937.

This piece of a trunk of Tempskya measures 4 by 6 

cm. It contains a few sections of stems surrounded 

by roots. The stems are relatively small like those of 

Tempskya knowltoni Seward from the Upper Cretaceous of Montana.

Occurrence: SW% sec. 28, T. 22 S., R. 22 E., Utah. 

In lower part of Dakota?, 100 feet above the Morrison 

formation. Collected by W, L. Stokes, 1944.
50 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1949

CYCADACEAE 

Cycadeoidea sp.

Plate 9, figure 13

This fragment of a cycadeoid trunk, showing part of 

a fruit and numerous leaf bases or traces, is too poorly 

preserved for specific identification.

Occurrence: In the basal part of the fPost-McElmo 

beds, not far above the unconformity with the fMcElmo. 

Southwest side of Little Gypsum Valley, San Miguel 

County, Colo. Collected by W. L. Stokes, 1946.

CONIFERALES 

Brachyphyllum crassicaule Fontaine

Plate 9, figures 5, 6

Brachyphyllum cr.assicaule Fontaine, U. S. Geol. Survey Mon. 

15, p. 221, pi. 100, fig. 4; pi. 109, figs. 1-7; pi. 110, figs. 1-3; 

pi. Ill, figs. 6, 7; pi. 112, figs. 6-8; pi. 158, fig. 9, 1889.

A number of Lower and Upper Cretaceous species of 

the conifer B rockyphyllum have been described, but 

methods for clearly distinguishing them, especially 

when possible variations in individual trees and parts 

of trees are taken into account, have not been stated. 

The situation has been reviewed by Berry (1911, p. 389).

The specimens in this collection are poorly preserved 

in respect to details, although in places enough of the 

spirally arranged, closely appressed leaves can be seen 

to permit reconstruction as shown in the illustrations. 

Assignment to Brachyphyllum, crassicaule Fontaine 

seems reasonable, although B. macrocarpum Newberry 

and B. parceramosum Fontaine are also very similar. 

The latter is a common Lower Cretaceous species, including, according to Berry, B. texense Fontaine, from 

the Glen Rose limestone of the Trinity group in Texas.

Figure 5 apparently represents the termination of a 

twig or a fruiting organ with elongated leaves or bracts.

Occurrence: In black shale in lower part of fPostMcElmo, south of Nucla, Colo. Collected by Junius 

Henderson and party, 1914>

Frenelopsis varians Fontaine

Plate 9, figure 12

Frenelopsis varians Fontaine, U. S. Nat. Mus. Proc., vol. 16, 

p. 273, pi. 40, figs. 1, 2; pi. 41, figs. l-3a, 1893.

This coniferous fragment is characteristic of the 

species, showing little or no development of leaves at 

the nodes, the twigs having served the function of 

leaves. The parallel rows of dots represent stomata.

The species was described from the Trinity group 

(Lower Cretaceous) on the .Paluxy River, near Glen 

Rose, Texas. It resembles most closely Frenelopsis 

parceramosa Fontaine (1889, p. 218) found in the

Patuxent formation of the Potomac group at Trents 

Reach, Va. The latter, however, displays a little leaf 

development at the nodes.

As Frenelopsis varians and its closest relatives have 

never been found in other than Lower Cretaceous strata, 

I am inclined to regard it as a Lower Cretaceous time 

index.

Occurrence: Black shale in upper part of fPostMcElmo but beneath basal sandstone of the Dakota. 

Collected by W. L. Stokes, 1945.

Sphenolepis kurriana (Dunker) Schenk

Plate 9, figure 14

Sphenolepis kurriana (Dunker) Schenk. Berry, Maryland 

Geol. Survey, Lower Cretaceous, p. 432, pi. 74, figs. 2, 3,1911. 

See extensive synonymy.

This many-named conifer, or a very closely related 

species, is common in Lower Cretaceous strata in Virginia, South Dakota, Montana, and California. Without attached fruits the species of /Sphenolepis are not 

readily distinguishable from one another.

Occurrence: In black shale in lower part of fPostMcEhno, south of Nucla, Colo. Collected by Junius 

Henderson and party, 1914.

JUGIAWDACEAE 

Juglans crassipes Heer

Plate 12, figures 8, 9

Juglans crassipes Heer. Lesquereux, U. S. Geol. Survey Mon. 

17, p. 69, pi. 49, figs. 1-3, 1892.

These specimens from southwestern Colorado seem 

to fall readily into this classification, but doubt must be 

entertained concerning the reference of the species to 

Juglans.

Occurrence: One and one-half miles southwest of 

coke ovens, Montrose County, Colo.

MORACEAE 

Ficus daphnogenoides (Heer) Berry

Plate 11, figures 1, 2, 5

Proteoides daphnogenoides Heer. Lesquereux, U. S. Geol.

Survey Terr. Kept, vol. 6, p. 85, pi. 15, figs. 1, 2, 1874. 

Ficus daphnogenoides (Heer) Berry, Torrey Bot. Club Bull.,

vol. 32, p. 329, pi. 21, 1905; Berry, U. S. Geol. Survey Prof.

Paper 129, p. 163, pi. 39, fig. 1, 1922. See synonymy.

These entire-margined leaves have been referred to 

many different genera with little satisfaction, as might 

be expected for entire leaves, the internal venational 

structure of which tends in many toward similarity. I 

regard the reference to Ficus as a makeshift. Many 

similar leaves from the Dakota sandstone have been 

referred with little evidence to Andromeda. All are
CRETACEOUS PLANTS FROM SOUTHWESTERN COLORADO 51

perhaps examples of lauifaceous species that are difficult 

to separate. At any rate, they are fairly abundant in 

early Upper Cretaceous strata.

Occurrence: Near junction of Disappointment Creek 

and Dolores River, San Miguel County, Colo. Collected 

by W. L. Stokes, 1945.

NYMPHAEACEAE 

Nelumbium sp.

Plate 10, figure 2

This fragment, with a portion of the entire margin 

and a number of the radial veins preserved, has the 

characteristic features of a waterlily leaf. It, however, 

is so imperfect that a specific designation does not seem 

warranted.

No waterlily has thus far been identified from Lower 

Cretaceous strata in the western states, but species 

appear in early Upper Cretaceous deposits.

Occurrence: One and one-half miles southwest of coke 

ovens, Montrose County, Colo.

BERBERIDACEAE 

Mahonia furnaria Brown, n. sp.

Plate 12, figure 4

Compound leaf with five lanceolate leaflets, the 

laterals being sessile, the terminal long-petioled. 

Margins serrate, with sharp teeth. Sinuses between 

the teeth scalloped. The secondary venation makes 

conspicuous internal, closed areas, with anastomoses 

and with thin branches to the teeth.

All the features of this leaf seem to ally it clearly 

with the genus Mahonia in the barberry family. If so, 

it may be in the ancestral line of the numerous species 

described from Eocene, Oligocene, and Miocene strata 

in the northwestern states.

Occurrence: One and one-half miles southwest of coke 

ovens, Montrose County, Colo.

LAURACEAE 

Sassafras cretaceum Newberry

Plate 11, figure 8

Sassafras cretacewn Newberry, TJ. S. Geol. Survey Mon. 35, p. 98, 

pi. 6, figs. 1-4; pi. 7, figs. 1-3; pi. 8, figs. 1, 2, 1898.

The blunt, rounded lobes, as well as the venation of 

this specimen, conform closely to those of Newberry's 

plate 8, figure 1, and to several figured by Lesquereux 

as /Sassafras cretacewn var. obtu&wn, and S. obtusum 

from the Dakota sandstone of Kansas and Nebraska. 

The reference of these leaves to Sassafras is questionable, but transfer to Ardlia, Araliopsis, Araliopsoides,

Platanus, Sterculia, or to some other genus is untimely 

and of no advantage so far as stratigraphy is concerned. 

Occurrence: Near junction of Disappointment Creek 

and Dolores River, San Miguel County, Colo.

PLATANACEAE 

Platanus newberryana Heer

Plate 12, figure 3

Platanus newberryana Heer. Lesquereux, TJ. S. Geol. Survey 

Terr. Kept., vol. 6, p! 72, pi. 8, figs. 2, 3; pi. 9, fig. 3, 1874.

The fragment figured here is the tip of the middle 

lobe of a leaf of this species. The scalloped sinuses between the teeth and the disposition of the secondary 

veins and their branches into the teeth are characteristic features.

Occurrence: One and one-half miles southwest of 

coke ovens, Montrose County, Colo.

CELASTRACEAE 

Celastrophyllum stokesi Brown, n. sp.

Plate 12, figures 1, 2

Lanceolate leaves, with rounded, crenate-dentate 

marginal teeth. Midrib strong. Secondary veins and 

intersecondaries form an anastomosing, more of less 

looped, network with short branches into the teeth.

This species approaches closely to G elastropfiyllimi 

ensifolium Lesquereux (1874, p. 108, pi. 21, figs. 2, 3) 

from near Fort Harker, Kans., but the leaves of the 

latter, especially Lesquereux's figure 2, are elliptic 

rather than lanceolate and the teeth are shorter and 

sharper. Berry (1911, pp. 474-481) recognized seven 

species of C elastrophyllum in the Patapsco formation, 

the species most closely resembling C. stokesi being perhaps G. acutidens Fontaine (Berry, 1911, p. 478, pi. 89), 

a specimen of which Ward had tentatively labeled G. 

pulcfirum. He, however, did not publish the name until later (1899, p. 706, pi. 171, figs. 3, 4) in connection 

with what he considered identical material from the 

Dakota of the Black Hills. G. stokesi may be the same 

as G. acutidens, but the leaves of the latter appear to be 

shorter and more elliptic. It is significant that, as 

Berry (1911, p. 475) pointed out, GelastrophyllMm is 

not present in the Patuxent and Arundel formations of 

the Potomac group. Neither is it present in any other 

formations attributed to the Lower Cretaceous. Consequently, this may be additional evidence for considering the Patapsco formation as Upper Cretaceous in age.

Occurrence: One and one-half miles southwest of 

coke ovens, Montrose County, Colo. Collected by W. L. 

Stokes, 1948, for whom the species is named.
52 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1949

STERCULIACEAE 

Sterculia towneri (Lesquereux) Berry

Plate 9, fig. 7; plate 11, figs. 3, 4

Sterculia, towneri (Lesquereux) Berry, U. S. Geol. Survey Prof. 

Paper 129, p. 217, 1922. See synonymy and cited figures.

These lobed Cretaceous leaves arouse considerable 

speculation as to separation of species and assignment 

to a definite botanical category. Berry's synonymy includes leaves from both Lower and Upper Cretaceous 

zones, and, therefore, if correct, the species cannot serve 

for distinguishing one zone from the other. Doubts, 

however, may well be expressed about the Berry synonymy, after examining numerous leaves from both zones.

Berry included under Sterculia towneri only lobed 

leaves with entire margins. A critical feature of the 

venation of these leaves must also be noted, namely, that 

the branching of primary veins from the midrib occurs at some distance above the top of the petiole and 

actual base of the blade. If the leaf is five-lobed, the 

lateral primaries fork at 1 or 2 cm. from the midrib. 

Thus the venational architecture is strikingly like that 

of Platanus. This pattern is also seen in the lobed 

Cretaceous leaves assigned by Lesquereux to various 

species of Aralia, Cissites, Liquidambar, and Sassafras. 

The lobes of the Aralia species, however, have more or 

less toothed margins, with scalloped sinuses between the 

sharp teeth, thus especially simulating leaves of Platanus. The association of similar, entire-margined 

with toothed-margined, lobed leaves that have been assigned to the same species in Paleocene, Eocene, and 

Oligocene strata in the northwestern states suggests a 

need for further study of the Cretaceous species here 

discussed and of Berry's Sterculia towneri synonymy.

Be all this as it may, the prime question so far as 

dating is concerned is whether any differences can be 

detected in these leaves that will permit separation of 

Lower and Upper Cretaceous strata. Unfortunately, 

too few of these leaves (except in the Cheyenne sandstone where they are not very well preserved), have 

been found in known Lower Cretaceous strata, thus 

giving perhaps an imperfect idea of their features. 

However, I find that the known Upper Cretaceous 

leaves are more deeply lobed, with a greater tendency to 

being toothed and with lobes that tend to be wider 

medianly. The Lower Cretaceous leaves are less deeply 

lobed, with scarcely any toothing, and the lobes tend 

to be cuneate, with scarcely any median widening.

It will be noted that the leaves here figured display 

the features noted for the Upper Cretaceous leaves. 

If, as seems most likely, the Lower Cretaceous leaves 

are immediately ancestral to those in the Upper Cretaceous it would not be surprising to find reversions or 

throwbacks to such leaves in Upper Cretaceous collections.

On this basis, the lobed leaves of the Lower Cretaceous Cheyenne sandstone, assigned by Berry to Sterculia towneri, ought perhaps to be given a new name, 

whereas those of the Upper Cretaceous Dakota sandstone remain S. towneri. The reassignment of some or 

all of these leaves to another genus than Sterculia must 

some day be considered.

Occurrence: Near'junction of Disappointment Creek 

and Dolores River, San Miguel County, Colo.

Capsulocarpus dakotensis Berry

Plate 9, figure 3

Capsulocarpus dakotensis Berry, Washington Acad. Sci. Jour., 

vol. 29, pp. 331-336, figs. 1-4, 1939.

The fruit here figured is considerably smaller than 

those reported by Berry from the Dakota sandstone 

near New Ulm, Minn., but resembles them in all other 

respects general outline, transverse plications, and 

marginal flange. As shown by Berry's figure 2 of the 

counterpart of his figure 1, the specimens with the 

flanges and transverse folds are casts of the interiors 

of fruits.

The relationship of this fruit is unknown. Except 

for the prominent flange, there is some resemblance to 

the fossil fruits of Cercidiphyllum, some of which are 

relatively large as compared with the fruits of the living species.

Occurrence: Near junction of Disappointment Creek 

and Dolores River, San Miguel County, Colo.

SPECIMENS OF UNCERTAIN IDENTITY

Plate 9, figure 1. This is part of a spherical fruit 

head with many closely packed, squarish carpels radiating from a round center. It may represent an early 

burreed, Sparganiwn. Disappointment Creek.

Plate 9, figure 2. This is a reticulately pitted seed 

that probably belongs with the fruit, plate 9, figure 1. 

Disappointment Creek.

Plate 9, figure 4. This may be the young stage of the 

fruit in plate 9, figure 1. Disappointment Creek.

Plate 9, figure 8. A lobed leaf, perhaps of a species 

of Sassafras. Black shale near base of fPost-McElmo.

Plate 9, figure 9. Perhaps a fragment of a cycad 

leaf. Black shale near base of fPost-McElmo.

Plate 9, figures 10,11. These are the narrow needlelike specimens identified by Berry as Pinus susguaensis 

Dawson. Such material also occurs in the Kootenai 

formation of Montana and in other Lower Cretaceous 

strata in the United States and Canada. However, the
CRETACEOUS PLANTS FROM SOUTHWESTERN COLORADO 53

"needles" have never been seen in fascicles, nor have 

authentic pine seeds been found with them, and consequently the identification as Pinus remains unconfirmed. Black shale near base of fPost-McElmo.

Plate 10, figure 1. A dicotyledonous leaf with unusually coarse, serrate teeth. One and one-half miles 

southwest of coke ovens.

Plate 10, figure 3. An undetermined fern. Four 

miles south of Nucla.

Plate 11, figure 7. Apparently a fruit or husk of a 

fruit. Disappointment Creek.

Plate 12, figure 5. A flower with 3 broad-based, 

alternating with 3 narrow-based oblanceolate petals or 

sepals. In the center are 3 striated seeds. This structure may represent a monocotyledon. One and onehalf miles southwest of coke ovens.

BIBLIOGRAPHY

Anderson, J. L., and others, 1948. Cretaceous and Tertiary 

subsurface geology: The stratigraphy, paleontology, and 

sedimentology of three deep test wells on the Eastern Shore 

of Maryland: Maryland Dept. Geology, Mines, and Water 

Resources, Bull. 2.

Berry, E. W., 1911. Lower Cretaceous flora of Maryland: 

Maryland Geol. Survey, Lower Cretaceous, pp. 214-508.

 1919. A new Matonidium from Colorado, with remarks 

on the distribution of the Matoniaceae: Torrey Bot. Club 

Bull., vol. 46, pp. 285-294.

 1920. The age of the Dakota flora: Am. Jour. Sci., vol. 

50, pp. 387-390.

 1922a. The flora of the Woodbine sand at Arthurs Bluff, 

Texas: U. S. Geol. Survey Prof. Paper 129, pp. 153-181.

 1922b. The flora of the Cheyenne sandstone of Kansas:

U. S. Geol. Survey Prof. Paper 129, pp. 199-225.

Berry, E. W., 1924. Mesozoic Gleichenia from Argentina: PanAm. Geologist, vol. 41, pp. 17-21.

 1939. Fossil plants from the Cretaceous of Minnesota:

Washington Acad. Sci. Jour., vol. 29, pp. 331-336. 

Brown, R. W., 1946'. Fossil plants and Jurassic-Cretaceous

boundary in Montana and Alberta: Am. Assoc. Petroleum

Geologists Bull., vol. 30, pp. 238-248. 

Cockerell, T. D. A., 1916. A Lower Cretaceous flora in Colorado:

Washington Acad. Sci. Jour., vol. 6, pp. 109-112. 

Coffin, R. C., 1921. Radium, uranium, and vanadium deposits

of southwestern Colorado: Colorado Geol. Survey Bull. 16.

 1924. Some anticlines of western Colorado: Colorado

Geol. Survey Bull. 24, pp. 1-68. 

Fontaine, W. M., 1889. The Potomac or younger Mesozoic

flora: U. S. Geol. Survey Mon. 15.

 1893. Notes on some fossil plants from the Trinity 

division of the Comanche series of Texas: U. S. Nat. Mus. 

Proc., vol. 16, pp. 261-282.

Krasser, Fridolin, 1896. Beitrage zur Kenntniss der fossilen 

Kreideflora von Kunstadt in Mahren: Beitr. Palaontologie 

und Geologic 5 sterr.-Ungarns, Band 10, Heft. 3, pp. 15-152.

Lesquereux, Leo, 1874. The Cretaceous flora: U. S. Geol. Survey 

Terr. Rept, vol 6.

Seward, A. C., 1926. The Cretaceous plant-bearing rocks of 

western Greenland: Royal Soc. London Philos. Trans., ser. 

B., vol. 215, pp. 57-175.

Stokes, W. L., 1944. Morrison and related deposits in and adjacent to the Colorado Plateau: Geol. Soc. America Bull., 

vol. 55, pp. 951-992.

 1948. Geology of the Egnar-Gypsum Valley area, San 

Miguel and Montrose Counties, Colorado: U. S. Geol. Survey 

Oil and Gas Investigations Prelim. Map 93.

Stose, G. W., 1912. U. S. Geol. Survey Geologic Atlas, Apishapa 

folio (no. 186).

Ward, L. F., 1899. The Cretaceous formation of the Black Hills 

as indicated by the fossil plants: U. S. Geol. Survey 19th 

Ann. Rept., pt. 2, pp. 527-712.

PLATES 9-12

55
PLATE 9

Figure 1. Undetermined fruit with squarish carpels. X 2.

2. Undetermined pitted seed. X 8.

3. Capsulocarpus dakotensis Berry x 2.

4. Undetermined fruit.

5. 6. Brachyphyllum crassicaule Fontaine.

7. StercuUa towneri (Lesquereux) Berry.

8. Probably a species of Sassafras.

9. Probably a fragment of a cycad leaf. 

10,11. Probably Pinus susquaensis Dawson.

12. Frenelopsis varians Fontaine.

13. Cycadeoidea sp.

14. Sphenolepis kurriana (Dunker) Schenk.

15. Tempskya knowltoni Seward.
GEOLOGICAL SURVEY PBO:FESSIONAL PAPER 221 PLATE 9

CRETACEOUS PLANTS
PLATE 10

Figure 1. Undetermined dicotyledonous leaf.

2. NelumMum sp.

3. Undetermined fern.

4. Asplenium sp.

5,6. Gleiclienia Jcurriana Heer.

7, 8. Matonidium americanum Berry.
GEOLOGICAL SUEVEY

PKOFE

CRETACEOUS PLANTS
PLATE 11

Figures 1, 2, 5. Ficus daphnogenoides (Heer) Berry. 

3,4. StercwUa towneri (Lesquereux) Berry.

6. Llavea hesperia Brown, n. sp.

7. Undetermined fruit.

8. Sassafras cretaceum Newberry.
GEOLOGICAL STTBVEY PKOFESSIONAL PAPEE 221 PLATE 11

CRETACEOUS PLANTS
PLATE 12

Figures 1, 2. Celastrophyllum stolcesi Brown, n. sp.

3. Platanus newberryana Heer.

4. Mahonia furnaria Brown, n. sp.

5. Undetermined flower.

6. 7. Bolbitis coloradica Brown, n. sp. 

8, 9. Juglans crassipes Heer.
GEOLOGICAL SURVEY PBOPESSIONAL PAPER 221 PLATE 12

CRETACEOUS PLANTS

INDEX

Page

acutidens, CelastrophyUum... ___________________________. 51 

Age of fossil plants _______________________________ 47-48 

althausi, Matonidium.......................................................... 46,48

americanum, Matonidium________________________ 46, 48-49, pi. 10 

Andromeda................................................................... 50

Aneimia.........................__________________________ 48

Ardlia................_________........____._.___...._____ 51,52

AraliopsiS-....................................__________________ 51

Araliopsoides........._..____ _________________________ 51

argentinica, Gleichenia......................................................... 48

Asplenium dicksonianum. .................................................... 48

sp.-__-_____________________________________ 48, pi. 10

Berry, E. W., quoted_________________________________ 46 

Bibliography______________________________________ 53 

Bolbitis..............______.______...- .____.______.._ 48

coloradica_________________________________ 49, pi. 12 

Brachyphyttum............................................................... 50

crassicaule........._.___ ____________________ 47,50, pi. 9

macrocarpum____________________________________ 50 

parceramosum ___________________________________ 50 

sp..__________________________________________ 46 

texense.................................................................... 50

Campium..............................................^..................... 49

Capsulocarpus dakotensis_____________________________ 52, pi. 9 

cardiomorpha, Pettaea......................................................... 49

Celastrophyttum.............................................................. 51

acutidens............... .__________.__._____________ 51

ensifolium.......................=.______________________ 51

pulchrum______________________________________ 51 

stokesi................................................................ 51, pi. 12

Certidiphyllum..--.............................________________ 52

Cissites............ -___ _-.... ..__....___._____ 46,52

Cladophlebis falcata montanensis_________________________ 46 

Cockerell, T. D. A., quoted..._________________________ 46 

coloradica, Bolbitis........................................................ 49, pi. 12

Colorado, fossil collections from_________________________ 45-47 

Disappointment Creek, fossils from_____________________ 52 

Little Gypsum Valley, fossils from_ ___________________ 46,50 

Morrison, fossils from_______________________________ 47 

Naturita, fossils from.___________________..._____ 46,48,49 

Nucla, fossils from.______________________________ 45,46,50 

Stone City, fossils from_______'____________________ 48 

cordifolia, Llavea....________________________________ 49

corrugata, Oryphaea..................................... __ .__________ 47

crassicaule, Brachyphyttum.............................................. 47,50, pi. 9

crassipes, Juglans....................._____________________ 50, pi. 12

cretaceum, Sassafras.^.................................................... 51, pi. 11

obtusum, Sassafras. ............_________________________ 51

Cycadeoiidea.................................................................. 48

sp. _ ..._ ...___._______________ 47, 50, pi. 9 

Cycadospadix......... ........................................________ 46,48

Dakota sandstone, section near Nucla, Colo.. _________________ 45 

dakotensis, Capsulocarpus.................................................. 52, pi. 9

daphnogenoides, Ficus. ........................................... ___ 50-51, pi. 11

Proteoides______________________________________ 50 

dicksonianum, Asplenium......... _________.___.___________ 48

ensifolium, CelastrophyUum................................................... 51

Equisetum..............................._____________________ 46

falcata montanensis, Cladophlebis.............................................. 46

Ficus___________________________________________ 50

daphnogenoides................ ................................... 50-51, pi. 11

Frettelopsis parceramosa....................................................... 50

varians. ......................................................... 45, 47, 50, pi. 9

furnaria, Mahonia_________________________________ 51, pi. 12

Page

giesekiana, Glsichenites. 

Gleichenia..............

argentinica .. .............. 48

kurriana.. ____________________________ 48, pi. 10

nordenskioldi... ._______ 46

Gleichenites...................................... 48

giesekiana.^.............................. 48

Gryphaea corrugata................................. ................ 47

newberryi..........._____ 45

Halymenites. _ 45,48

Henderson, Junius, quoted.___.________ ______ 46

hesperia, Llavea.................._____ ___ 49, pi. 11

Heteroneuron.........._ __ 49

Humata ophioglossoides........._ 49

Juglans....................___ 50

crassipes.. ___________ _____ 50, pi. 12

knowUoni, Tempskya.....-.____________ 49, pi. 9

kurriana, Gleichenia_________________ __ 48, pi. 10 

Sphenolepis^____________________________ 46, 47, 50, pi. 9

Liquidambar____________ -__._ _ 52 

Llavea................................._____ ______ 49

cordifolia.______________________-______________ 49 

ia-... ............... .- . _ . 49, pi. 11

McElmo formation, section near Nucla, Colo... ___ 45 

macrocarpum, Brachyphyttum................................__ 50

Mahonia..............._ __ 51

furnaria................................__ 51, pi. 12

Mancos shale, in section near Nucla, Colo....._ _ 45

Matonidium............. ........ _ 48

althausi.______________________________________ 46,48

americanum..'________ _ - 46, 48-49, pi. 10

Matonia pectinata..........___ 49

wiesneri.... __________ _______ . 49

montanensis, Cladophlebis falcata_________ 46 

mudgei, Sassafras..................________ 46

Nelumbium sp__ ______- 51, pi, 10

newberryana, Platanus_________.____ . 51, pi. 12

newberryi, Gryphaea.........._ _ 45

nordenskioldi, Gleichenia_________________.____ __ 46

obtusum, Sassafras... ......._ 51

Sassafras cretaceum......................... 51

Onychiopsis....................................__ 46,48

ophioglossoides, Humata......................__ 49

parceramosum, Brachyphyttum 50 

parceramosa, Frenelopsis.......... 50

pectinata, Matonia_________ - _ 49 

Pettaea cardiomorpha________________ ._ ..__ _ 49 

Pinus-. ................................................................ 53, pi. 9

susquaensis____________________-_______ 46, 47, 52-53, pi. 9 

Platanus__________________________________________ 51,52

newberryana___________________ ____ - 51, pi. 12 

Poecilopteris_______________________________________ 49 

Post-McElmo, section near Nucla, Colo______________________ 45 

Previous investigations______________ _______ _____ 45-47 

Proteoides daphnogenoides..___ .___ 50 

pulchrum, Celastrophyttum_____________.___ ____ . -_ 51

Sapindopsis______________________-_______ _____ 46 

Sassafras.......................................... .-...... ... 51, 52, pi. 9

cretaceum. _____________________________ _ 51, pi. 11 

cretaceum obtusum________._...____ __ 51 

obtusum____________________________ ___ 51

mudgei.. ___________________________________ 46

65
66 INDEX

Page

Section near Nucla, Colo.. ____________________________ 45 

Significance of the fossil plants __________________________ 47-48 

Sparganium ___________________________________ 52, pi. 9 

Sphenolepis _____________________ - ______________ 50 

kurriana 46, 47, 50, pi. 9

___ __ .... 51,52

towneri... ___________________ . __________ 52, pis. 9, 11 

stoked, Celastrophyllum ___________________ . ____ . ____ 51, pi. 12 

susquaensis, Pinus ________________ ________ 46, 47, 52-53, pi. 9

Page 

Tempskya.. ______ __ .. 49

knowUmi...________-_____-____.___ ___- 49, pis. 9 

lexeme, Brachyphyllum.-------___ 50

towneri, Sterculia.___________________-____-____ 52, pis. 9,11

Utah, fossil collections from. 49

varians, Frenelopsis_____ __ 45, 47, 50, pi. 9 

wiesneri, Matonia.. 49

o