The malacologicalsocietymalacological society of Japan

fima VENUS (Jap. Jour, Malac.) Vel. 42. No.3 (1983):248-258

rkhYslh[LLzz;deXfrwEee Deltoidonazatilzts K

)i- 9 A ff l ff CD 1 ;ef ff

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･es ')': i}Z ( lttt' Jc P.Il d;ii suIttil iR fi:-1･ M[ V'7i. )

A New Species of Deltoidonautilus (Cephalopoda) from the Upper Eocene of western Kyushu

Kazushige TANABE and Noboru CHIBA

(Department of Earth Sciences, Faeulty of Seienee, Ehime University,

Matsuyama 790, Japan)

Intreduction

The Paleogene Okinoshima Formation in the Okinoshima Island, Takashima

Coal-Field, Western Kyushu yields abundant shallow marine mollusean fossils.

In 1959, Kobayashi and Kamada first described the gregarious occurrenee of a

nautilid, Eutrephoceras iapcmicum (.Shimizu) from the formation, and sub-

sequently they considered its taphonomieal and palaeobiogeographical implica- tions (Kobayashi and Kamada, 1959a-b).

Since the works by Kobayashi and Kamada, more than 300 fossil nautilid

speeirnens have beeii collected from the limited horizon of the Okinoshima For-

mation. Most of them were obtained by students of Nagasaki Minami Senior

High Sehool under the guidance of Mr, S. Horiguehi. The senior author pre- viously observed the nautilid speaimens stored in the high sehool, and at that

oceasion he noticed preliminarily that only several specimens are assigned to ,E. iaponicum, but the remaining ones are referable to another species of the

Nautilaceae. The junier author made a further field work in the Okinoshima

Island in 1980, and colleeted several additional nautilid specimens from the same bed as that of E. iaponieum described by Kobayashi and Kamada (1959a). On the examination of some well-preserved speeimens in the collections of

Nagasaki Minami Senior High School and Ehime University, the authors have

arrived at the conelusion that they represent Aturia･ yokoyamai Nagao and a new

speeies of DeLtoidonautilus, which is deseribed below.

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Tanabe . Chiba: A New Species of Deltoidonautilus from Upper Eocene 249

Systematic Description

SUBCLASS NAUTILOIDEA Agassiz, 1847

ORDER NAUTILIDA Afiassiz, 1847

Superfamily NAUTILACEAE de Blainville, 1825

Family HERCOGLOSSIDAE Spath, 1927

Genus Deltoidonautilus Spath, 1927

7iype-$pecies: Natttitus Sozverbyi J. de C. Sowerby, 1843

Re7narics: Kurnmel (1956, p. 452-457) regarded this genus as a junior synonym

of Angzalithes Montfort (1808). Indeed, Montfort's (1802, pl. 49) A. tria･nguttzris,

the type speeies of Anyulithes (the original illustration of the type speeimen

is reproduced in Kummel, 1956, pl. 25, fig. 1) is similar to Deltoidona･utitus species

in the triangular whorl section. But the suture of the Montfort's (1802) type

illustration is mueh simpler than the sinuous ones of Dettoidonautitus. Neverthe-

less, Kummel (1956) interpreted that Montfort's illustration of the suture is

oversimplified; for many of the nautilid specimens referable to A. triangula7'is

from the type loeality have a sinuous suture. However, the type speeimen of

Montfort's (1802) tTianguta?fiis. was probably missing. For the above reason,

Montfort's Angzalithes is now treated as a doubtful genus (nomen dub.) in the

Treatise (Kummel et al., 1964, K456). As Kurnmei (1956) has already emphasized,

Deltoidonautitus is in many respects transitional to both Cimomia and Herco-

glossa of the same family, differing mainly in the subtriangular whorl section.

The degree of sinuosity of the sutures in Deltoidonautilus is also intermediate

between those of the latter two genera (see Kummel, 1956, figs. 32, 34). Deltoi-

donautilus is a world-wide genus, known from the Upper Cretaeeous to the

Oligocene (Kummel et al., 1964), and most of the Tertiary species are Eeeene

in age (Kummel, 1956, fig. 30).

Deltoidbnautilus okinashimensis n･ sp･

(PL 1, figs. 1-2; Pl. 2, fig. 1; Fig. 2)

?1959b. Entrephoceras y'apon･icxtvn. (Shimizu). Kobayashi and Kamada, p.105-114, pL 10, fig. Ia (only),

Types: Holotype, EE.1035 from Aze, southwestern eoast of the Okinoshima

Island, Nagasaki Prefecture (see Fig.1 for the detailed loeations). K. Tanabe

coll. Paratypes, EE.1036, 1039 from almost the same loealities as that of the

holotype. N. Tsuchiya and others coll. These speeimens are now stored at

Department of Earth Sciences, Ehime University.

Material: In addition to the above type speeimens, many of the unregistered

specimens stored at Nagasaki Minami Senior High School are referable to the

present speeies.

Diagnosis: Large sized species of Deetoidonautilus, eharaeterized by its dis-

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250 VENUS: VoL 42. No. 3 (1983)

N 'iNDEXMAPi l:..t.-- 130E 132'fi34'-d x eo;･r･EEJ),,.:. o ."

oo0 -.-.--l.tv'i o tt i.-:t} IJ･.f.- . ) o oCop 10J 1MA ' s. -ao) '/Lx Q'ij \ 32'N ./. tts e"eenny t;t-" : ob ee t.. J[:, eO"+-: 'so e oe e V o ee .oqo .Oo - e ege eo e eeeoq

t-Lt--r;-J-tLL-.- oeaoe eoe

oeo i:" oe

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A[tuviurn ([;] OKINOSHI IllllllZ Daimyofji Member :.k -9ecaEL. ': EtsL ill- Funazu Member

rd.g

l6' El;l2iMagome Member t

S Okineshima Formation

Fautt O 2SOm ts

Fig. 1. Geological map of the Okinoshima Island, Western Kyushu, showing and herizon of Del- toidonautilzasokinoshimensisn.sp.(EE. 1035- 1036, 1039) and Aturia yofeoyainai (EE. 1037'-1038) (afterChiba, 1981 MS). ri- ;l= 1 y--tV2. thY (EE.1035-1036, 10:S9) SS .t V` Aturia yohoyamai 1037-1038) CDIEts'af]Ji-ggft[leli / a) lfi{,VilT,e ttecairscl 19s1 2cA.N }･izX E))

coidal whorls, with subtriangular cross section, narrowly rounded venter, in-

volute, very narrow umbilieus, adorally convex fine and deiise ribs, and sinuous

sutures possessing a broad and high lateral sadd!e. Description: Shell large-sized for the genus, sometimes exeeeding 20em in diameter, involute, discoidal in outline; body chamber lenger than a half whorl;

whorls widest at umbilical shoulder, higher than breadth with subtriangular

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Tanabe.Chiba: A New Species of Deltoidonautilus from Upper Eocene 251

B

10mm H c

at H=48mm at H-=-31mm

Fig. 2. Deltoidonautii"s okinoshimenst-s n. sp. Drawings of right lateral (A), and dorsal (B) views and external sutures (C) of the holotype (EE. 1035). f- ;} 7 v?tg A h"I oF. ec JktuJ!ts (EE. 1035) a) )CJ'MU tm (A), Wfi (B), ti X Ve me fi wt (C) O )K tiJ v tl.

cross seetions; venter sharply rounded; flank very long, gently convex, and con-

verges toward venter; umbilieal shoulder well defined, umbilical zone narrow,

descending obliquely into umbilieus; umbilicus very narrow and shallow; whorl

surface smooth except for fine and dense grewth lines, like Recent Nautitus;

growth lines regular-spaced with a rounded top, being adorally fiexuous and

retreating deeply for sharply curved hypotenic sinus; siphuncular position uncertain; septa elosely spaced, numbering about 8-9 per a half whorl; external

sutures sinuous, consisting of a broad and high lateral saddle, and equally broad

lateral lobe, and an acute ventral saddle, being lower than broad lateral saddle,

lateral saddle and lobe of almost equal in width.

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252 VENUS: VoL 42, No,3(1983)

Measurements (in mm) :

Whorl Whorl Diameter height(H) breadth(B) Umbilicus B/H Holotype (EE.1035) 105 67 23.5+ O.35 Paratype (EE.1036) 20e 98 32+ O.33 Paratype (EE. 1039) 122 50+ O.41 Obse･rvation and compa74ison: Among the large number of speeirnens stored at

Nagasaki Minami Senior High School and Ehime University, only the holotype

and one of the paratype (EE. 1036) have almost eomplete outline, although their whorls are partly fractured and have been suffered from a slight lateral defoT- mation during fossilization. They as well as other paratype, however, well

preserve the diagnostie eharaeters of the present species such as the sub- triangular whorl seetion and sinuous sutures. Speeimen I deseribed by Koba-

yashi and Kamada (1959b, fig. 3B) as a laterally deformed exarnple of Eutre- phoceras o'aponieum from the Okinoshima Formation may be attributed to the present species, because its discoidal whorl seetion is quite different from the jnflated whorl sections of other speeimens of E. e'aponieum from the same formation (see Kobayashi and Kamada, 1959a, pl.9, figs.1-2; Kobayashi and Kamada, 1959b, fig.2, fig.3A, C-D). Incidently the present speeies is easily distiiiguished from E. iaponicu･m of the Nautilidae in the more sinuous sutures

and more depressed whorl sections.

D. ekinoshi7nensis is most closely allied to Dettoidonautilus Sow･erbyi (J. de C. Sowerby) (Newton and Harris, 1849, p. 127 for the revised deseription; see Stenzel, 1940, figs.123-124 for the diagrammatie whorl section and suture) from the Eocene London Clay of England in the suture pattern and the diseoidal

whorl sections, but the lateral saddle of the suture is more broadly rounded in

the present speeies. DeLtoidonazatietts senegcttensis (Douvil16) (Douvil16, 1920, p.121, 137, 139, 141-143, pl.1, figs.3a-b; Miller, 1951, fig.14) and Deltoidonaut-itus etLioti Stenzel (1940, p.759-764, pl.38, figs.1-6, pl.39, figs.1-2; text-figs.123(2) & 124(2)) from the Middle Eocene of Senegal and Texas respectively, also resemble

the present species in having the sinuous sutures, but the former two are distinguished from the latter by their much higher ventral saddle in addition

to the larger whorl breadth in relation to whorl height.

The present species is somewhat similar to the following Eocene Dettoido-

nautitus species in the general outline of the shells; i.e. D. deluci (d'Archiae)

from western India (Miller, 1951, fig.11A-B for the redrawn d'Arehiae's illus- tration of the holotype), D. spathi Haas and Miller (1952, p.342-343, pl.29,

fig. 3, pl. 30, figs. 1-2; fig. 7) from Somalia, and D. chudeaui (Douville) CDouvill6, 1920, p. 121, 137, 139, 140-141, pl.1, figs.5a-b) from Sudan; but the sutures of

the latter three species are mueh simpler than that of the former.

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Tanabe . Chiba: A New Species of Deltoidonautilzas from Upper Eocene 253

Oecu?-rence and geotogical ho7'izon: The present species is found abundantly in the lower to middle part of the Okinoshima Formation in the Okinoshima Island, together with Ezttrephoceras o'aponicum and Aturia yoleoyamai (Pl.2,

fig.2). The latter two species are, however, rare in occurrence. According to

the foraminiferal and molluscan biostratigraphy by Murata (1961) and Mizuno (1962a-b), the formation is assigned in age to the Auverisian to the Bartonian

(Upper Eocene).

Concluding Remarks

This paper is a first record of Dettoidonautilus from the Japanese Islands.

As already described Dettodona.2tt'itus oicinoshimensi,s occurs abundantly i'n the

limited horizon of the Okinoshima Formation in the Okinoshima Island, West

Kyushu. Important bivalves assoeiated are Venewieard･ia･ nipponica, Pi,ta･r icyze-

shu･ensis, Cattista 7natsu?'ensis and Photadomya. sp., and most bivalve specimens

are complete and conjoined. Many speeimens referable to the present speeies in

the collection of Nagasaki Minami Senior High School have an almost complete

body chamber, although their last whorl has, in most eases, been suffered from a

slight secondary deformation, as in the speeimens of E. jupon･icum and A.

uokoyamai from the same bed. The lithology comprising the nautilid assemblage

is fine- to medium-grained glaueonitic sandstone or sandy siltstone, and no

sedimentary strueture suggesting a strong bottom current is recognized in the

nautilid-bearing beds. Judging from these lines of evidence, we support Koba-

yashi and Kamada (1959b) in their interpretation that the nautilid assemblage

in the Okinoshima Formation was accumulated within or near the habitat realm

of relatively shallow water.

Acknowtedgements: We are greatly indebted to MessTs. S. Horiguchi and K. Saka-

guchi, the former and present teachers of Nagasaki Minami Senior Hig'h School

respeetively, for making valuable material available to us. We speeially thank Dr.

T. Matsumoto (Professor Emeritus of Kyushu University) for critieal reading of a first version of the manuscript. Useful taxonomieal discussions were provided by

Drs. T. Matsumoto and C. Teiehert (Professor of the University of Rochester), te

whom we express our sincere gratitude. Thanks are extended to Professors H.

Matsuo (Ehime University) and Y. Kamada (Nagasaki University) for their en-

eouragements, and Messrs. Y. Miyata {Kyushu University) and N. Tsuchiya (Geologi-

cal Survey ef Japan) for giving us information about fossil loealities. Mr. A. Ishida

of Ehime University kindly assisted us in preparing the phetographs.

I tw

ftiltiRi'tii1 Sfb}c･f>Jfti'#L6LMSdeIXMViFi !lfffhli 5C･ik, IkJ[ilri' ij vx Vi'･t Xia) Eutrephoceras iaponi- -C 'C cum (Shimizu) ab: Kobayashi and Kamada (1959 a b) eC t o va tll, " tt L i 6. gZ 6eM Ko-

bayashi and Kamada }': k Z) E. juponicum L e･:C･t'Ea I;nctiphi6Ns- C) 2i.Vt gipXeC) t :) tH ab'･t ncItJEi

'JJv'wtl/･l ;E L'lt$J{'JII, CDi[,l': E. ]'aponicum, Aturia yokoyamai Nagao t-ece= DeJtoidonautil"sMeta

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254 VENUS ： Vol．42， No ．3 （ユ983）

’ め ら れ る 新 種 を 見 い 出 し た の で ， こ こ に D ．oleinoshimesnSt s （新 称 オ キ ノ シ マ オ ウ ム ガ イ ） と し て 記

“ ” 載 す る 。本 種 は 大 型 で 円 盤状 の 外 観 を 呈 し ，亜 三 角型 の 螺 環 断 面 ， 密 巻 き で 狭 い へ そ ， お よ び 多

数 の 細 肋 を 伴 う 殻 で 代 表 さ れ ，縫 合 線 は 本 属 特 有 の 波 形 の 曲 線 で 特 徴 づ け ら れ る 。 オ キ ノ シ マ オ ウ ム

ガ イ は ，円 盤 状 の 形 態 や 縫 合 線 の 様 式 な ど の 点 で ， 本 属 模 式 種 で 英 国 の London Clay （始 新 統 ）産

の D ． べ て い の Sowerbyi （J．de C ．Sowerby ， 1843 ） に 類 似 す る が ，後 者 に 比 よ り 広 く 高 縫 合 線 側 面 の 山 を 有 す る こ と で 区 別 さ れ る 。1）eltaidonautitus 属 は 汎 世 界 的 に 後期 白 亜 紀 か ら 漸 新世 に か け て 繁

栄 し ，世 界．各 地 か ら 化 石 例 が あ る が ， 日 本 か ら は 今 回 の オ キ ノ シ マ オ ウ ム ガ イ が 始 め て で あ る 。な お

沖 ノ 島 層 か ら 多産 す る オ ウ ム ガ イ 類 化 石 の 多 く は 本 種 に 含 め られ る で あ ろ う。沖 ノ 島 層 か ら産 す る オ

ウ ム ガ イ 類 化 石 は ， 多 数 の 個 体 が 住 房 部 を よ く 残 し た ま ま 見 い 出 さ れ る こ と か ら ， Kobayashi and ’ Kamada （1959 b ） が か つ て 指 摘 し た よ う に 大 部分 の 個 体 は 生 息 域 内 も し くは そ の 付 近 て 堆 積 し た と 一 ・ 考 え ら れ る 。記 載 標 本 の 部 は 長 崎 南 高 校 の 生 徒 に ょ って 採 集 さ れ た も の で ，同 校 の 堀 口 承 明 （当時 ）

阪 冂 和 則 （現 在 ） 而 教 諭 を 通 じ て 愛媛大 学 に 寄 贈 し て い た だ い た 。記 し て 深 く 感謝 す る 。

References

， Douvill6 ， H ．1920 ． L Eoc6ne au Soudan et au S．6n6gal ． Butl ．σom ・Etudes 正1｛st ・Sci・

A 吃 α nc α ・ ： − ．− ． ∫r gue Oceidentotles Fr ise， （2 ） 113 171 ， pls 1 5

Haas 0 ． and Miller A ． K ． ． Amer ． ， ， 1952 Eocene nautiloids of British Somaliland ．Buel．

Mus ． N α ． ． ： − ．21 −31 ． t HiSt ， 99 317 354 ， pls

Kobayashi T ． and Kamada Y ．1959a ． An Eocene nautiloid from Kyushu Japan ． ， ， ，

」α ・ ． ．σ θ og γ ．30 ： 105 − 114 ， P Jour Geol ， ， p1 ．9

Kobayashi T ． and Kamada − 一 − − ， Y ．1959b ． Bio thana セ） and fossilhistory of Ezatre ， ， ，

んoce 「 as aPoni （nt ？7t・ 」α ・ ． − P ゴ P Jour Geol．Geogr ．， 30 ： 115 125 ， pI．10．

Kummel B ．1956 ． Post − nautiloid ． Bull ． Mus ．σ o ？np ． Zoot ． H α rvard ， Triassic genera ，

Unin ．114 ； − ．1−28 ． ， 324 484 ， pls

Kummel B ． Furnish − ， ， W ．M and Glenister B ．F ．1964 ． Nautiloidea Nautilida In ： ， ， ．

Moore ， R ． C ．（ed ．）： Tre α tise ・ 冗 lnvertebrate Paleentology ， Part K （M ・ tluscα 3 ）：

K383 −K466 ． GeoL Soc ． Amer ．＆ Univ ． Kansas Press ．

Miller， A ． K ． 1951 ． Tertiary nautiloids of west −coastal Africa ． Ann ． tl4zts ． Congo

ser ．8 s6f ． ． − − Belge ， ， geol ， 8 ： 1 88 ，pls ．1 31 ．

Mizuno A ． ， ．1962a ． Paleogene and Lower Neogene b 量ochronology of Wes 七 Japan （1）．

．JotcT． Geol ． Soc 」 α α n ： − with abstract ． p ， 68 64 （〉 648 （in Japanese English ＞．

Explanation of Plate 1 − Figs ．1 2． Deltoidonautilus okinoshimensis sp ． nov ， オ キ ノ シ マ オ ウ ム ガ イ （新 種 新 称 ） Specimens from the Upper Eocene at Aze coast of the Okinoshima

Island， Nagaski Prefecture ． 1 ，Westen．Kyushu （’see Fig for the detailed fossil localities），図 示 し た 標 本 は 酋 丿L 州 長 崎 県 V・［i ノ 島 の 畦 海 岸 に 分 布 す る 上 ノ 部 始 新 統 沖 島 層 産 （産 地 は 第 1 図 を 参 照 の こ と ）。

1 ： Paratype （EE ．1036）． Dorsal （a ）， ventral （c ） and left lateral （b ） views ，All X 2f3．K ．Ogawa coll ．副模 式 慓 本 （EE ．1036 愛媛 大 学 収 蔵）。 背 面 （a ），腹 面 （c ）， お よ び 左 側 面 （b ）。 2 ： Paratype （EE ．1039 ）． Left lateral view of a part of a body chamber of the large specimen ． X 1／2． N ． Tsuchiya aad others co11 ．副 模 式 標 EE ．1039 一 本 （ 愛 媛 大 学 収 蔵 ）。 住 房 部 の 部 の 左 側 面 。 All photos whitened ．

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Tanabe .Chiba: A New Speciesef Deltoidonautilus from UpperEocene 255

Plate 1

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256 VENUS ： Vo1．42 ， No ．3 （1983 ）

Explanation of Plate 2 『 ー Fig ．1． Deltoidonautilus okinoshimensis sp ． nov ．オ キ ノ シ ／ オ ウ ム ガ イ （碧テ種 ・新 称 ） Holotype （EE ．1035 ）． Dc）rsal （a ）， ventra1 （c ：） and right lateral（b） views of the entire shell ， and left lateral view （d ） of the phragmocone ． See Fig ．1for the detailed locality． All X 1． K ． Tanabe coll ．完 模 式 標 本 （．EE ， 1035 a c 愛 媛 大 学 収 蔵 ）、 背 面 （）， 腹 面 （ ） お よ び 右 側 面 （b ） と 気 万｝部 分 の 左 側面 〔d ）。産 地 の 詳 細 は 第 ユ 図 を 見 よ 。

Fig ．2 ． Aturia yokoyamai Nagao ． Left lateral view of the specimen ， EE ．1037 ， The locality is almost the same as those of D ． oleinoshimensis （see Fig ．1〕． ． ． and others coll EE 1037 X1 N Tsuchiya ．（ ． 愛 媛 大 学 収 蔵 ） 右 側 面 。 All photos whitened ．

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Tanabe.Chiba: A New Speciesof Deltoidonautitus from UpperEocene 257

Plate 2

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258 VENUS: Vol. 42, No.3(1983)

Mizuno, A. 1962b. Paleogene and Lewer NeDgene biochronology of West Japan (II). Jour. Geol. Soc. Japan, 68: 687-693 (in Japanese with English abstract). Mentfort, D.D. 1802. Histoire naturelle, generale et particulibre des Mollusques, animaux sans vertebres et b sang blane; Ouverage faisant suite h 1'histoire naturelle g6n6rale et particulibre, eomposee par Leelerc de Buffon, et redig6e par C. S. Sennini, rnembre de plusieurs Soci6tes savantes. Paris, 4: 1-376, pls.42-50. Montfort, D.D. 1808. Conehyliologie systematique et classifieation methodique des eoquiles; offrant leurs figures, leur arrangement gen6rique, leurs deseriptions caraeteristiques, leurs noms; ainsi que leur synonymie en plusieurs langues. Paris, 1: 409 p. 100 pls.

Murata, S. 1961. Paleogene microbiostratigraphy of North Kyushu, Japan. Bull. Kyushu Inst. Technol. (Math. & Nat. Sci.), (8): 1-109, pl.1. Stenzel, H.B. 1940. Tertiary nautiloids from the Gulf Coastal Plain. Texas Univ. Pub. (3945): 731-794, pls. 35-42.

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