Bulletin of the Tateyama Caldera Sabo Museum,Vol.9, pp.1-10（2008）

A gigantic ammonite from the Upper Jurassic Arimine Formation of
the Tetori Group, Japan
Masaki Matsukawa 1)* , Kazuto Koarai 2) , Makiko Fukui 1) , Koji Suzuki 1) , Yutaka Ogawa 1) ,Shigeru Kikukawa 3) , Masahiro Kometani 3) and Toshikazu Hamuro 4)

1) Department of Environmental Sciences, Tokyo Gakugei University, Koganei, Tokyo 184-8501, Japan
2) Keio Shonan Fujisawa Junior and Senior High School, Fujisawa 252-8522, Kanagawa, Japan
3) Tateyama Caldera Sabo Museum, Tateyamamachi 930-1407, Toyama, Japan
4) Toyama Paleontological Society, Imizu 939-0303, Toyama, Japan*Corresponding author: matsukaw@u-gakugei.ac.jp

Abstract
A gigantic ammonite specimen discovered from the Arimine Formation of the Tetori Group in the eastern part of the
Jinzu section is described as Perisphinctes (Kranaosphinctes) matsushimai Yokoyama. The specimen, measuring over 25
cm in diameter, is one of biggest specimens reported from the Tetori Group. The occurrence of the species suggests that
the Arimine Formation can be assigned to the Perisphinctes matsushimai Assemblage Zone of Middle Oxfordian, Late
Jurassic. The Kiritani Formation, distributed in the western part of the Jinzu section, also contains fossils assigned to thePerisphinctes matsushimai Assemblage Zone and is thus correlative with the Kiritani Formation. Both formations were
deposited during the first transgressive phase in the Tetori area.
Key words: gigantic ammonite, Arimine Formation, Perisphinctes (Kranaosphinctes) matsushimai, Middle Oxfordian

Introduction

discuss the changes of terrestrial environments and theiraccompanying terrestrial and fresh-water biota.

As late Mesozoic terrestrial deposits are widely distrib-

The Tetori Group is represented by different outcrops inuted on the Asian continent and include various kinds

the Mt. Hakusan and Jinzu sections. Recently, two strati-of zoo- and phyto-assemblages, they are suitable for un-graphic sequences of the group in the Mt. Hakusa area

derstanding the changes of terrestrial environments andwere redefined as lithostratigraphic units of the group

their accompanying terrestrial and fresh-water biotas. To

and the unified definitions and nomenclature for thesehelp understand this significance, a suitable chronologicalstrata were given (Matsukawa et al., 2006, 2007). Then,

scale for these deposits is required.

based on occurrence of ammonites, the Tetori Group

There are marine intercalations within the upperis correlated with Callovian to Oxfordian, Tithonian to

Mesozoic nonmarine successions of the eastern part ofBerriasian and Hauterivian to Barremian (Sato, 1962;

the Asian continent, including the eastern part of theSato and Westermann, 1991; Sato et al., 2003,2008;

Heilongjian Province, China and the Tetori area, Japan.

Matsukawa et al., 2007).

It is, therefore, possible to assign the marine stage no-

The Tetori Group in the Jinzu section reflects the eastern

menclature for these nonmarine deposits. We can, then,distribution of the group and consists small, localized− 1 −Masaki Matsukawa , Kazuto Koarai , Makiko Fukui , Koji Suzuki , Yutaka Ogawa , Shigeru Kikukawa , Masahiro Kometani and Toshikazu Hamuro

Fig. 1. Map showing ammonite locality in the Arimine region. Thick line represents the route along which columnar sectionof the Arimine Formation (Fig. 2) was measured along Higashisakamori-dani Creek. Index map shows distributionof the Tetori Group in two sections.

marine deposits in its lower part and widespread terrestrial deposits in its upper part. Although there are diverse
opinions about the stratigraphy of the upper part of theTetori Group in the Jinzu section (Maeda and Takenami,
1957; Kawai and Nozawa, 1958; Takenami and Maeda,
1950), there is an accordance of opinion concerning
its lower marine deposits. These marine deposits are
assigned to two formation, the lower, Magawa and upper,
Arimine formations (Figs. 1, 2). To date, an occurrenceof the Jurassic ammonite Kranaosphinctes sp. in theArimine Formation was listed by Maeda and Takenami(1957), who showed the formation can be correlated with
the Oxfordian stage. Subsequently, Kranaosphinctes sp.
from the Arimine Formation has been used as an age
constraint for the Oxfordian in a number of geologicalstudies, including these of Kawai and Nozawa (1958),
Takenami and Maeda (1959), Maeda (1961), Toyama Prefecture (1992), and Toyama Board of Education (2002).
However, paleontological descriptions and illustrations ofFig. 2. Columnar section of the Tetori Group along theHigashisakamori-dani Creek, Toyama Prefecture,
Japan.

−2−ammonite specimens from the Arimine Formation have
not yet been presented.

A gigantic ammonite from the Upper Jurassic Arimine Formation of the Tetori Group, Japan

We collected a gigantic ammonite specimen identi-

Geological setting

fied as Perisphinctes (Kranaosphinctes) matsushimai
Yokoyama from Higashisakamori-dani creek in Arimine

The Tetori Group is one of the principal late Mesozoic,

area, Toyama Prefecture, Japan. The specimen measures

dominantly terrestrial deposits of East Asia, withover 25 cm in diameter and preserves the original

commonly found taxa in the area. The Tetori Group isshape and surface ornamentation. This species was

distributed in two separate locations, the Mt. Hakusan

named as Perisphinctes (Procerites) matsushimai by

and Jinzu sections. The Mt. Hakusan section contains the

Yokoyama (1904) based on specimens from the Jurassic

main “type” stratigraphic sections of the group and bears

shale in Echizen province (present Fukui Prefecture).

rich zoo- and phyto-fossils. There are three stratigraphic

Sato and Westermann (1991), then, used Perisphinctes

sequences of the group in the Mt. Hakusan section: the(Kranaosphinctes) matsushimai as an assemblage zone

Kuzuryugawa sequence, the Hakusan sequence andspecies of the Perisphinctes (Kranaosphinctes) matsushi-

the Hida-Furukawa sequence (Matsukawa et al., 2006,

mai Assemblage Zone, assigning the zone to the Middle

2007) (Fig. 3). In the Kuzuryugawa region, the group

Oxfordian, with the Yambarazaka Formation in Kuzuryu

can be divided into eight formations: the Shimoyama,area in Fukui Prefecture as type locality.

Tochimochiyama, Kaizara, Yambarazaka, Yambara,

In this paper, we present a paleontological description of

Ashidani, Izuki and Nochino formations in ascending

the specimen from the Arimine area and discuss the age

order. In the Hakusan area, the group can be divided intoof the Arimine Formation.

nine units: the Ushimaru Formation, Mitarai Formation,

Fig. 3. Geological correlation of the Tetori Group between Hakusan and Jinzu sections based on ammonite indices andmarine trangressive phases.

−3−

Masaki Matsukawa , Kazuto Koarai , Makiko Fukui , Koji Suzuki , Yutaka Ogawa , Shigeru Kikukawa , Masahiro Kometani and Toshikazu HamuroOtamiyama For mation /Gomishima Conglomerate

Department of Environmental Sciences, Tokyo Gakugei

Member, Okurodani Formation /Kuwajima Formation,

University, Koganei. Tokyo (TGUSE).

Amagodani Formation, Okura Formation and Bessandani

Terminology. In general, morphological terminology

For mation in ascending order. Then, in the Hida-

follows Arkell et al. (1957), and adjectives used in

Furukawa region, the group can be divided into six

descriptions are in accordance with the definition offormations: the Tanemura, Numamachi, Sugizaki/Tochio,

Matsumoto (1988).

Taie and Inagoe formations, in ascending order.

Abbreviation. D: diameter; U: umbilicus (expressed as

Ammonites are found in the Kaizara and Yambarazaka

a percentage of diameter); H: whorl height; W: whorl

formations in the Kuzuryugawa region, in the Ushimaru

width; W/H: width/height ratio.

and Mitarai formations in the Hakusan area, and in
the Inagoe Formation in the Hida-Furukawa region.

Class: Cephalopoda von Zittel, 1884

Ammonite indices suggesting Callovian and Oxfordian

Order: Ammonoidea von Zittel, 1884

ages occur in the Kaizara and Yambarazaka formations,

Suborder Ammonitina Hyatt, 1889

suggesting that Tithonian to Berriasian exists in the

Superfamily Perisphinctaceae Steinmann, 1890

Ushimaru and Mitarai formations and suggesting that

Family Perisphinctidae Steinmann, 1890

the Hauterivian to Barremian are present in the Inagoe

Subfamily Perisphictinae Steinmann, 1890

Formation. Consequently, three sequential marine

Genus Perisphinctes Waagen, 1869

transgressions can be recognized in the Tetori area:

Subgenus Kranaosphinctes Buckman, 1921

Middle to Late Jurassic Callovian to Oxfordian, Jurassic

Per i sphincte s (K ranaosphincte s) mat su shimai– Cretaceous transition from Tithonian to Berriasian, andYokoyama, 1904
1904 Per i sphincte s (Procer ite s) mat su shimai;

Early Cretaceous Hautervian to Barremian.
In the Jinzu section, the Tetori Group can be divided
into five formations and one member in ascending order:
the Magawa, Arimine/Kiritani, Ioridanitoge, and Inotani
formations, and the Minamimatadani Conglomerate
Member. Five units, the Magawa and Arimine formationsof the lower part of the group, and the Ioridanitoge andInotani formations and the Minamimatadani Conglomer-

Yokoyama, p. 3-4; pl. 1, fig. 1.
1962 Kranaosphinctes matsushimai; Sato, p.86-88; pl.
2, figs. 4a, 8; pl. 7, figs. 1, 2, 3, 4, 5; pl. 9, fig. 7.
1972 Kranaosphinctes matsushimai; Suzuki and Sato,p.214-215, fig. 2.
1990 Kranaosphinctes matsushimai; Shimonoya and
Takahashi, pl. 25, fig. 4.

ate Member, in the upper part, can be recognized in the2002 Kranaosphinctes matsushimai; Fukada, pl. 2, fig. 2.

Tetori Group. Based on lithologic characteristics andMaterial. A single specimen, TGUSE-MM 5220 (K.

fossil evidence, the lower unit consisting of the Magawa

Koarai and Y. Ogawa Coll.), from the lowermost blackand Arimine formations suggests shallow marine envi-

mudstone unit of the Arimine Formation (Higashisaka-ronments, while the unconformably overlying upper unit,

mori-dani Creek).

consisting of the Ioridanitoge and Inotani formations andMeasurements (in mm).

the Minamimatadani Conglomerate Member, suggest

Description. The specimen is very large, ca. 280 mm inallvial fan and meandering river environments.
A gigantic ammonite has been collected from blackshale of the lower part of the Arimine Formation along
Higashisakamori-dani creek in the Arimine region.

Systematic description

Specimen

D
U
TGUSE-MM 5220 278(1) ca130(0.47)

H

Half-whorl earlier, costa
Half-whorl width, costal

68.8

W/2

(W/2)/H

27.6

0.80

diameter, with moderately involute whorl with a fairly
wide umbilicus, <50 % of diameter in later growth-stage,

Repository. The specimen illustrated is deposited in the−4−

being moderate in early growth-stage. Whorl is polygyral

A gigantic ammonite from the Upper Jurassic Arimine Formation of the Tetori Group, Japan

Fig.4. Perisphinctes (Kranaosphinctes) matsushimai Yokoyama, 1904 from the Arimine Formation in HigashisakamoridaniCreek, Toyama. Scale shows 5 cm.

−5−Masaki Matsukawa , Kazuto Koarai , Makiko Fukui , Koji Suzuki , Yutaka Ogawa , Shigeru Kikukawa , Masahiro Kometani and Toshikazu Hamuro

and shows subtrapezoidal cross-section with somewhat(UMUT MM7054, University Museum of the University

convex flanks, and much compressed, with W/H aboutof Tokyo), from the Yambarazaka Formation, Tetori

0.40 in later growth-stage.

Group, at Nagano, Fukui Prefecture (Yokoyama, 1904,

Surface is ornamented by primary, secondary, and inter-pl. 1, fig. 1), has three secondary ribs at early growth-calated ribs. Primary ribs are narrow and sharp, forming

stage, and two secondary and intercalated ribs at its

subtriangle sections and arising at the umbilical margin.

continuously later growth-stage. As well, the specimen

They branch into four or five secondary ribs at one-of Kranaosphinctes matsushimai from the Yambarazaka

fourth of the distance along the flank from the ventral

Formation, Tetori Group, at Nakajima, Fukui Prefecture

margin. Intercalated ribs present are between secondary(UMUT MM3789)(Sato, 1962, pl. 2 fig. 6) has single

ribs. Deep and wide constrictions, appear periodically,

primary ribs at early growth-stage, and two secondary

crossing both secondary and iniercalated ribs.

ribs, intercalated ribs and sometimes a single primary

Remarks. Specimen is similar to the illustrated specimen

rib at its continuously later stage. The specimen ofof Kranaosphinctes matsushimai from the probableKranaosphinctes matsushimai from the Yambarazaka

Yambarazaka Formation, Tetori Group, at Nagano,

Formation, Tetori Group, at Nagano, Fukui Prefecture

Fukui Prefecture (Shimonoya and Takahashi, 1990, pl.

(UMUT MM3785) (Sato, 1962, pl. 2, fig. 5, pl. 7, fig. 1)

25, fig. 3), in having four secondary ribs branched fromdisplays two secondary ribs. The sparse primary ribbing

primaries. Variable ribbing patterns can be recognizedof the present specimen is similar to that seen on theon specimens identified as Kranaosphinctes matsushimai

illustrated specimen of Kranaosphinctes matsushimaifrom the Tetori Group in Japan (Fig. 5). For example,(Fukada, 2002, pl. 2, fig. 2), held at the Omori Inn at

the holotype of Perisphinctes (Procerites) matsushimai,

Oginohama, Miyagi Prefecture; this specimen is now
housed at the Fukada Geological Institute, Tokyo.
Kranaosphinctes matsushimai (Suzuki and Sato, 1972,
p. 214-215, fig. 2), probably from the Torinoko Formation
at Ohira, Mashiko, Tochigi Prefecture, also shows
similar sparse ribbing, but this specimen, typically, hastriplicate secondary ribs, while our specimen has fouror five secondary ribs. The illustrated specimen (IGPS
7178, University Museum of the Tohoku University) of
Kranaosphinctes cf. matsushimai from the Oginohama
Formation at Aritahama, south of Oginohama, Ishinomaki city, Miyagi Prefecture, northeast Japan (Takahashi,
1969, pl. 14, fig. 5), is also different from the present
specimen in having dense primary ribs.
Although Glowniak (2002) def ined the subgenus
Kranaosphinctes as having bifurcate secondary ribs
and intercalatory ribs between the secondaries, variableribbing patterns can be recognized in Japanese specimens
assigned to the subgenus. Almost all Japanese specimens
possess constrictions and can thus be identified as theFig. 5. Comparison of secondary ribbing of specimens
identified as Perisphinctes (Kranaosphinctes)
matsushimai Yokoyama. A and D are the holotype,
UMUT MM7054; D shows enlarged part of laterstage of shell. B is UMUT 3789. C is UMUT 3785.
Scale bars show 1cm.

−6−

subgenus Kranaosphinctes based on the criteria ofArkell et al. (1957).
Occurrence. Middle Oxfordian (Arimine Formation) ofHigashisakamori-dani creek, Toyama Prefecture, Japan.

A gigantic ammonite from the Upper Jurassic Arimine Formation of the Tetori Group, Japan

sequence is subdivided into the Magawa and Arimine
Geological age of the Arimine Formation offormations, in ascending order. These marine formations

the Tetori Groupare all unconformably overlain by the Ioridanitoge
Formation, consisting of alluvial fan deposits.

Sato and Westermann (1991) showed the Jurassic

The Kiritani Formation consists mainly of coarse

regional ammonite zones of East Asia and Southeast

sandstone and bears abundant specimens of the genus

Asia, including Japan, the Philippines, Thailand andNipponitrigonia. Perisphinctes (Dichotomosphinctes)

Indochina, Indonesia, and N.W. Papua-New Gunea.

kiritaniensis Sato is also noted in the formation (Sato,

Regarding Japan, thirteen regional zones, consisting1962). Based on Sato and Westermann (1991), the Kiritaniof three Lower Jurassic zones, seven Middle Jurassic

Formation is defined of the Perisphinctes matsushimaizones, including the Hosoureites ikianus Assemblage

Assemblage Zone, indicating Middle Oxfordian. This

Zone which ranges down into the Upper Toarcian, andsuggests that the Kiritani Formation can be correlated

three Upper Jurassic zones were distinguished. Four ofwith the Arimine Formation. Based on lithologic char-these Middle and Upper Jurassic zones were recognizedacteristics of their molluscan fossil-bearing units, thewithin the Tetori Group in Mt. Hakusan section; theKiritani Formation is characterized by coarse sandstone

Pseudoneuqueniceras yokoyamai Assemblage Zone isand conglomerates while the Arimine Formation isdefined in the lower part of the Kaizara Formation of thecharacterized by black shale and muddy sandstone. The

Tetori Group as type zone,;the Kepplerites japonicus As-

common molluscan species are rare in both formations;semblage Zone, indicating earliest Callovian, is defined

the Kiritani Formation bears common specimens of thein the middle part of the Kaizara Formation as typegenus Nipponitrigonia while the Arimine Formation

zone; the Oxycerites Assemblage Zone, indicating Early

bears abundant specimens of the genus Myophollera but

Callovian, is defined in the upper Kaizara Formation as

no record of the genus Nipponitrigonia. The different

type zone; and the Perisphinctes matsushimai Assem-

molluscan assemblages suggest that both formations

blage Zone, indicating Middle Oxfordian, is defined inreflect different depositional environments. Tashiro andthe Yambarazaka Formation of the Tetori Group as typeMatsuda (1988) interpreted that the genus Nipponitrigo-

zone.

nia inhabited shallow-marine beach environments. The

As a gigantic ammonite specimen from the Arimine

genus Myophollera ornamented with many nodes on its

Formation is identified as Perisphinctes (Kranaosphinc-shell surfaces, can be interpreted to inhabit mud bottomstes) matsushimai Yokoyama, the Arimine Formationin the deep sea, as Stanley (1970) shows relation between

can be correlated with the Yambarazaka Formationthese shell characteristics and such environments. Basedof the Tetori Group of the Mt. Hakusan Section, andon environmental differences of trigonians, the Kiritani

can be assigned to the Middle Oxfordian. Previousely,

Formation in the west seems to be shallower than the

Maeda and Takenami (1957) suggested the Arimine

Arimine Formation in the east. This concurs with theFormation can be correlated with the Oxfordian based on

hypothesis that western hinterland to the Tetori Group

Perisphinctes sp. Our study supports this previous study.

depositional basin existed during the Late Jurassic(Matsukawa et al., 1997).
Matsukawa et al. (2007) showed three sequentional

Geological correlation and environments

marine transgressions can be recognized in the Tetori
There are two isolated distributions of marine rocks

area, during Callovian to Oxfordian, Tithonian to Ber-within the dominantly nonmarine Tetori Group in theriasian, and Hauterivian to Barremian, while two marine

Jinzu section. In the eastern exposures of the Jinzu

transgressions, late Oxfordian to Volgian (approximately

section, the marine formation is named as the Kiritani

equivalent Tithonian to early Berriasian) and BarremianFormation, and in the western section, the marine

to Aptian, can be recognized in the Heilongjiang area of−7−

Masaki Matsukawa , Kazuto Koarai , Makiko Fukui , Koji Suzuki , Yutaka Ogawa , Shigeru Kikukawa , Masahiro Kometani and Toshikazu Hamuro

China. Consequently, two regional marine transgressive

Dr. S. Fujii, graduate students and under graduates of

events, Oxfordian to Berriasian and Barremian to Aptian,Matsukawa Laboratory in Tokyo Gakugei University.

are recognizable along the east margin of the Asian

Dr. T. Sasaki supported us to study specimens housed

continent during Late Jurassic to Early Cretaceous time.

in Museum of University of Tokyo. The study was

Discrepancies in the timing of marine transgressions

financially supported in part by the fund of the Grant-in-

between the Tetori and Heilongjiang are considered to be

Aid for Scientific Research(B) of the Japanese Society forcaused by differences in regional diastrophism and thethe Promotion of Science (Hasegawa, no. 11791012, 2006-

distances of the basins from the ocean. Therefore, the2008).

Arimime and Kiritani formations appear to have been
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von (Ed.), Handbuch der Paläeontologie. 1(2)Oldenbourg, Munich/Leipzig, pp. 329-522.

【要 旨】
上部ジュラ系有峰層（手取層群）から産出した巨大なアンモナイト
松川正樹・小荒井千人・福井真木子・鈴木浩司・菊川茂・小河佑太力・米谷正広・葉室敏和
富山県東部の手取層群の有峰層から産出した巨大なアンモナイトは，Perisphinctes (Kranaosphinctes)

matsushimai Yokoyamaに分類・同定され，本論文で古生物学的に記載される．記載する標本は，直径25cmを越え，これまで手取層群から報告されたアンモナイトの中で最も大きいものの１つである．このアンモナイト種は日本
ではジュラ紀後期のオックスフォーディアン期中期を指示するPerisphinctes matsushimai帯の示帯種なので，この種の産出により有峰層はその時代を示す．従って，有峰層は富山県下に分布する桐谷層に対比され，両層は手取地域における最初の海進期に堆積したものであると解釈できる．

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