bull. kitakyushu mus. nat. hist., 6: 239-264.march …...fossil teeth of the genus carcharodon have...

Bull. Kitakyushu Mus. Nat. Hist., 6: 239-264. March 20, 1987

Oligocene Lamnid Shark of the genus Carcharodonfrom Kitakyushu, Japan.

Yoshitaka Yabumoto

Kitakyushu Museum ofNatural History, Nishihonmachi,Kitakyushu, 805Japan

(Received April 20, 1986)

Abstract Sixteen fossil teeth of the lamnid shark, Carcharodon angustidens, fromKitakyushu are described here. These teeth are from a bed of the Ashiya Group whichis considered to be the Late Oligocene. There is a wide range of morphologicalvariations among these fossil teeth, which represent individual and positional differenceson the jaw.

Introduction

Fossil teeth of the genus Carcharodon have been abundantly discovered not only inJapan, but in various parts of the world. Cappetta (1970) recognized 8species and onesubspecies of the genus Carcharodon in the world. Fossil teeth belonging to several speciesof the genus Carcharodon have been found in more than 40 localities in Japan, ranging fromHokkaido to Miyakojima Island of the Ryukyu Islands (Goto, 1972; Uyeno et al., 1974).Five species of the genus Carcharodon are reported from Japan. These species are C.carcharias from Pliocene to Recent, C. tnegalodon from Miocene to Pliocene, C. akitaensisfrom Miocene in Akita Prefecture (Uyeno and Hasegawa, 1974), C. sulcidens fromMiocene in Mie Prefecture (Uyeno et al., 1980) and C. angustidens from Oligocene inKitakyushu (Uyeno et al., 1984). Uyeno et al. (1984) briefly reported six fossil teeth of C.angustidens from the Islands ofAinoshima and Kaijima that are in the Ashiya group. Theage ofAshiya group is considered here as the Late Oligocene (Nagao, 1927; Matsushita,1949; Hirayama, 1956; Murata and Mokudai, 1959; Mizuno, 1963). This paperdescribed 16 teeth of C. angustidens from the Islands of Ainoshima, Kaijima, andHimeshima, Tomoro Beach of Wakamatsu, northern part of Kitakyushu City', andMizumaki which is located west of Kitakyushu City. All localities belong to members ofthe Ashiya Group.

Acknowledgment

I am very grateful to Dr. Teruya Uyeno of National Science Museum for hisinvaluable advice and critical reading of the manuscript. I like to express my sinceregratitude for cooperation of the owners of the specimens, Mr. Toshiyuki Kamei, Mr.

240 Yoshitaka Yabumoto

Hideo Ikeuchi, Mr. Masatoshi Okayama and Miss Noriyo Kida. I thank Mr. Koichi

Mukaibo for donation of his specimen. I am grateful to Dr. Ryuzo Toriyama and Dr.Masamichi Ota of Kitakyusyu Museum of Natural History for their constantencouragement. I thank Mr. Atsushi Fujii and Mr. Yoshihiko Okazaki of KitakyushuMuseum of Natural History, and Mr. Takashi Okamoto of the University of Tokyo for

their cooperation in collecting the specimens.

Methods

The tooth terminology is based mainly on Applegate (1965). The method of themeasurements in shown in Figure 1,which is based on Uyeno (1975). The counts of the

l-OH

outer surface inner surface anterior viewFig. 1. The method of the measurements of a fossil tooth of Carcharodon angustidens, right

upper jaw tooth.

small dent

small dents

minute dents

Fig. 2. Small dents and minute dents on cutting deges.

Oligocene Lamnid Shark of the genus Carcharodon 241

serration include small dents and minute dents (Fig. 2).

Locality. The Islands of Ainoshima, Kaijima, and Himeshima (130°49'E, 33°59'N), the rock of Hiroiwa (130°49'E, 33°60'N), Sakamizu (130°42'E, 33°50'N) andTomoro Beach (130°43' E, 33°50' N) in Kitakyushu City, Yoshida (130°42' E, 33°5l' N)Mizumaki-cho in Onga County. These localities are in the Fukuoka Prefecture, northernpart of Kyushu.

Horizon. Tomoro beach belongs to the Waita Fromation, Sakamizu belongs to theSakamizu Formation and the other locaties belong to the Yamaga Formation(Matsushita, 1949, 1969) in the Ashiya Group, Upper Oligocene.

Description

Class Chondrichthyes

Order Lamniformes

Family Lamnidae

Genus Carcharodon

Carcharodon angustidens (Agassiz)

The measurements and counts of the specimens are shown in Table 1.

Upper jaw teeth

The tooth is wide and low. The crown stands erect or inclines to the rear. Theinner (lingual) surface of the crown is convex. The outer (labial) surface is generallyflattish, but sometimes slightly concave or slightly convex. The outer surface of thecrown is slightly concave at the central part near the base ofthe crown and slightly convexnear the apex of the crown. Serrations of both cutting edges are equal in size. Thetooth neck is narrower than that of the lower jaw tooth. The inner surface of the root isconvex. The convexity of the central part of the inner surface of the root is notremarkable, except one specimen which is considered to be an anterior tooth. The outersurface of the root is slightly concave or flattish. The concavity of the root's radialmargin is shallower than that ofthe lower jaw teeth. Seven specimens ofupper jaw teethare described as follows.

Kamei's specimen 1. This specimen was collected from Kaijima Island byToshiyuki Kamei (Fig. 3, Uyeno et al., 1984; pi. 3-2). This is a left upper jawtooth andis considered to be an anterior tooth. The apex of the crown is broken and about 1mmof both cutting edges are missing. The coronal half of the posterior (distal) cusp ismissing. The crown is broad and stands erect. The central part of the inner surface ofthe crown is flattish. The outer surface is flattish and slightly convex along the centralaxis near the apex, but slightly concave along the central axis just above the crown base.Both cutting edges are almost straight and slightly convex outwards at the middle of the


Table 1. The measurements and counts of the fossil teeth of

Kamei's KMNH Kida's Okayama's KMNH KMNH Ikeuchi's Ikeuchi's

specimen VP specimen specimen VP VP specimen specimen1 100,093 1 1 100,112 100,113 1 2

a-b 30.7mm+ 13.2+ 30.0 — 20.0+ 6.4+ 31.8+ 49.0

a-b' 26.7 + 9.7 + 25.5 20.9+ 17.1 + 3.9+ 27.0+ 38.7

a-c 38.8+ — 36.7 35.6+ 21.5+ 11.9+ 31.0+ —

a-g 41.0+ 24.3+ 40.6 40.2 + 32.8+ 15.9+ 47.7+ 63.3

H 50.3 + 28.6+ 49.7 48.4+ 40.3 + 17.0+ 58.5+ 83.3

a-k 47.7 + — 46.6 44.0+ 30.5+ 21.8+ 50.1 + —

b-e 11.2 5.1 7.8 — 7.0 6.7 8.4 20.0

c-g 37.2 — 40.8 47.0 34.5 28.1 48.0 40.1 +

d-f 41.0 — 44.3 48.1 38.0 29.9 50.6—

i-h 11.0 7.6 10.1 — 9.1 7.1 13.9 26.6

b'-n 2.8 1.8 1.9 3.4 0.6 2.2 3.5 10.2

m-1 26.0 — 27.9 28.7 20.6 17.5 32.8 30.9

m-g 8.7 8.9 8.4 12.9 9.5 8.9 10.8 10.0

1-c 7.9 — 7.0 11.9 7.1 6.4 9.4—

q-s 6.1 4.0 5.4 — 6.2 6.3 —10.5

r-t — — 5.5 — 5.1 7.2 — —

o 7.5 6.6 7.4 — 7.0 7.7 8.2 15.1

P* 10.6 6.9 10.0 — 8.5 4.7 11.1 21.9

a-m 33.0+ 15.8+ 32.9 29.2+ 31.7 + 7.1 + 39.0+ 54.3

a-1 31.3+ 5.2+ 30.9 26.2+ 23.5+ 5.9+ 33.2+ 47.9+

Counts

serration of

a-m 42 27+ 47 52 38+ 10+ 43 + 67 +

a-1 40 8+ 49 46 29+ 10+ 40+ 63+

m-g 16 20 17 28 20 21 6+ 23

1-c — —17 25 15 20 5+ —

* Maximum thickness of the root at the central part.

crown and inwards near the apex of the crown. There are 42 serrations on the anterior(mesial) cutting edge. The anterior cutting edge has 14 to 16 indentations within 10 mmdistance. The blade of the anterior cutting edgeis continuous to the anterior cusp, but anotch is present between the anterior cutting edge and the anterior cusp. There are 40serrations on the posterior cutting edge. The posterior cutting edge has 14 to 16indentations within 10 mm distance. The anterior cusp has 16 serrations. There are 10indentations on the anterior edge and 5 indentations on the posterior edge, with thelargest and the broadest one at the apex ofthe anterior cusp. The dent on the anterioredge near the apex ofthe anterior cusp is the second largest while the other dents near theroot are smallerin size. Four dents on the posterior edge of the anterior cusp are similarin size and the dent at the anterior end of the edge is smaller than these dents. Both

Oligocene Lamnid Shark of the: genus Carcharodon

Carcharodon angustidens from the Ashiya group. See Fig. 1.

KMNH

VP

100,092

Kamei's

specimen2

KMNH

VP

100,090

KMNH

VP

100,116

KMNH

VP

100,114

Ikeuchi's

specimen3

KMNH

VP

100,115

KMNH

VP

100,091

39.2 + 45.2+ 47.2+ 54.3 26.5+ 36.9+ 22.8+ 24.3 +

32.0+ 33.7+ 39.0+ 43.2 15.9+ 26.4+ 18.0+ 20.0+

45.1 + 52.1 + 60.0+ — 21.1 + 47.0+ — —

47.6+ — 60.9+ 74.3 — 39.0+ — —

60.3 + — 76.5+ 85.4 — 51.0+ — —

57.0+ 66.0+ — — 38.6+ — — —

7.9 9.9 14.7 13.7 10.0+ 12.0+ — —

35.9 29.4+ 42.8+ — — 43.6+ — —

39.8 — 57.3 — — 48.4+ — —

11.7 16.8 19.5 21.4 11.9 18.8 — —

4.2 8.5 7.1 6.9 4.5 6.4 3.1 3.0

27.2— 32.0

— — 33.0 18.7 + 26.0+

6.2 — — 10.8 — 9.1 — —

5.4+ 4.1 9.8+ — 7.0+ 8.0+ — —

4.9— — 9.4+ — 6.8 — —

4.5+ 3.9 6.8 — 7.6+ 7.3+ — —

8.8 9.2 11.1 13.3 8.8 10.5 5.9 9.2

11.4 13.8 16.4 20.0 12.0+ 14.5 — —

42.5+— 50.0+ 63.9 — 30.2 + 25.2+ 27.0+

38.6+ 47.9+ 49.7+— 21.1 + 40.1 + 26.1 + 24.1 +

61 + 35+ 49+ 84 35+ 41 + 45+ 39+

50+ 67 + 54+ 44+ 27+ 57 + 20+ 28+

— — — 15 — 18 — —

— 14 10+— 10+ 15

— —

243

surface of the anterior cusp are slightly convex and the outer surface is more convex than

the inner surface of the cusp. The anterior cusp is thin along the blade and thick at itsbase. The width of the crown (Fig. 1, c-g) is 37.2 mm. The maximum thickness of thecrown is 7.5 mm and 20.2% of the crown width. The maximum width of the tooth neck

is 2.8 mm and 7.5% of the crown width. The tooth neck narrows rapidly at the anteriorand the posterior ends. The inner surfaceof the root is convex and particularly convexatthe central part. The anterior part of the root extends radially and its margin is circularin outline. The posterior margin of the root is circular in outline. Small convexities are

present near both lateral cusps on the root. The concavity of the root's radial margin isrounded. The outer surface of the root is flattish, but the narrow part along the toothneck is slightly concave. The posterior and the anterior parts of the root inclineoutwards(Fig. 3C).


Fig. 3. Kamei's specimen 1. A, outer surface; B, inner surface; C, anterior view.Scale 10 mm.

the anterior parts of the root incline outwards(Fig. 3C).

KMNH VP 100,093. This specimen was collected from Ainoshima Island by

Atsushi Fujii (Fig. 4, Uyeno et al., 1984; pi. 3-3). This is a left upper jaw tooth. Theapex of the crown, the posterior part of the crownand the root, and the central part of theinner surface of the crown are missing. The tooth is the smallest in size among the

collected specimens. The tooth is almost an equilateral triangle in shape. The crown isthick and both sides of the crown are prominently convex. The narrow part of the outer

surface along the anterior cutting edge is convex. There are 27 serrations on thepreserved anterior cutting edge which is 15.8 mm. The anterior cutting edge has 15indentations within 10 mm distance. The blade of the anterior cutting edge is continuous

to the anterior cusp (Fig. 4D). The preserved posterior cutting edge of the crown is 5.2mm and it is the middle part which has 8 serrations. The anterior cusp is low andcontinuous to the anterior cutting edge of the crown (Fig. 4D). The anterior cusp has 20indentations. There are 11 on the anterior edge and 8 on the posterior edge with the

largest one at the apex of the anterior cusp. The dent at the middle part of the anterioredgeof the anterior cusp is the second largest. Bothsides of the anterior cusp arc equallyconvex. A ridge is present on the inner surface of the anterior cusp at the anterior endnear the tooth neck (Fig. 4D). The maximum width of the preserved tooth neck is 1.6mm. The tooth neck reaches below the anterior end of the lateral cusp and is black along

the base of the crown. The inner surface of the root is convex. The outer surface of the

root is concave along the baseof the crown and is slightly convex at the radial part. Theradial margin of the root appears to be deeply concave almost like the V shape.

Kida's specimen 1. This specimen was collected from Tomoro Beach, Wakamatsu,Kitakyushu City by Noriyo Kida (Fig. 5, PI. 1-1). This is a right upperjaw tooth. The

Oligocene Lamnid Shark ofthe genus Carcharodon

Fig. 4. KMNH VP 100,093. A,outersurface; B, innersurface; C, anterior view,D, anterior cusp. Scales 10 mm.

245

specimen is considered to be a lateral tooth. The specimen is almost completely

preserved except for about 5 mm of the posterior cutting edge near the apex of the crown

which is broken and missing. The crown slightly inclines to the rear. The apex of the

crown is pointed and curves outwards (Fig. 5C). The inner surface of the crown is

convex, but flattish at the middle central area. The outer surface of the crown is flattish,

but slightly convex at the coronal part and the anterior part near the root. There are

three grooves from the base to the middle part of the crown at the central part of the outer

surface. The anterior groove is the longest and the deepest. These grooves become

gradually short and shallow close to the rear. The anterior cutting edge is concave near

the base of the crown and slightly convex near the apex of the crown. There are 47

serrations on the anterior cutting edge. The anterior cutting edge has 14 and 15

indentations within 10 mm distance. The blade of the anterior cutting edge is continuous


Fig. 5. Kida's specimen 1. A, outer surface; B, inner surface; C, anterior view.Scale 10 mm.

to the anterior cusp, but a notch is present between them. The anterior cutting edge ison thesame plane with theanterior cusp. The posterior cutting edge is concave near thebase of the crown and almost straight from middle to the apex of the crown. There are49 serrations on the posterior cutting edge. The posterior cutting edge has 12 to 15indentations within 10 mm distance. The blade of the posterior cutting edge iscontinuous to the posteriorcusp, but a deep notchis presentbetween them. The anteriorcuspslightly inclines to the front. Thereare 17 serrations on the anteriorcusp, 12 on theanterior edge and 4 on the posterior edge, with the largest and the broadest one at theapex of the anterior cusp. Three dents on the anterior end of the anterior cusp areminute. There are 17 serrations on the posterior cusp, 4 on the anterior edge and 12 onthe posterior edge, with the largest and the broadest oneat the apex of the posterior cusp.The dents become gradually smaller close to the front and the rear. One dent on theposterior end of the posterior cusp is minute. Both surfaces of lateral cusps are equallyconvex. The width of the crown is 40.8mm. The height of the crown (Fig. 1, a-b) is30.0 mm and 73.5% of the crown width. The maximum thickness of the crown is 7.4 mm

and 18.1% of the crownwidth and 24.7% of the crown height. The tooth neckis narrowand the maximum width is 1.9 mm and 4.7% of the crown width and 6.3% of the crown

height. The inner surface of the root is convex and more convex at the central part.The anterior and posterior parts of the inner surface of the root are flattish. The outersurface is slightly convex at the anterior and the posterior parts and slightly concave atcentral part. The maximum thickness of the root is 10.0 mm occurring at the centralpart. The posterior part of the root is thinner than the anterior one. The concavity ofthe root's radial margin is the V shape.

Okayama's specimen 1. This specimen was collected from Ainoshima Island by

Oligocene Lamnid Sharkof the genus Carcharodon

Fig. 6. Okayama's specimen 1. A, inner surface; B, anterior cusp; C, posterior cusp.Scales 10 mm.

247

Masatoshi Okayama (Fig. 6, PI 1-4). This specimen is cleaned only the inner surface, onthe rock with mollusc and the shark tooth of the genus Odontaspis. The specimen is aright upper jaw tooth. The apex ofthe crown is broken and about 5 or 6mm ofbothcutting edges are missing. The crown slightly inclines to the rear. The anterior cuttingedge of the crown is almost straight. There are 52 serrations on the anterior cutting edge.The anterior cutting edge has 20 indentations at the middle part and 18 indentations nearthe base of the crown within 10 mm distance. The blade of the anterior cutting edge iscontinuous to the anterior cusp (Fig. 6B). The posterior cutting edge is slightly concave.There are 46 serrations on the posterior cutting edge. The posterior cutting edge has 14and 15 indentations at the middle part and 18 indentations near the base of the crownwithin 10 mm distance. The blade of the posterior cutting edge is continuous to the


posterior cusp with a notch (Fig. 6C). There are 28 serrations on the anterior cusp and25 serrations on the posterior cusp(Fig. 6B, C). Three dents at the anterior end of theanterior cusp and six dents at the posterior end of the posterior cusp are minute. Thewidth of the crown is 47.0 mm. The maximum width of the tooth neck is 3.4 mm and7.2% of the crown width. The radial part of the root is flattish at central part and isslightly concave at the anterior and the posterior parts. The concavity ofthe root's radialmargin is rounded.

KMNH VP 100,112. This specimen was collected from Ainoshima Island byAtsushi Fujii (Fig. 7, PI. 1-2). This is a left upper jaw tooth, probably a lateral tooth.The apex ofthe crown is broken and about 8mm ofboth cutting edges are missing. Thecrown strongly inclines to the rear and is twisted outwards at the posterior part. Theinner surface of the crown is convex, but flattish at the middle central area. The outersurface of the crown is flattish. About one fifth of the central part from the base of theouter surface is slightly concave with a low, weak ridge running from the center ofthe baseto the middle part of the crown (Fig. 7A). The middle and coronal part of the outer

L 1

Fig. 7. KMNH VP 100,112. A, inner surface; B, outer surface; C, anterior view; D,outer surface ofanterior cusp; E; outer surface ofposterior cusp. Scales 10 mm.


surface of the crown is slightly convex. The anterior cutting edge is almost straight.

There are 38 serrations on the anterior cutting edge. The anterior cutting edge has 16 to18 indentations within 10mm distance. The blade of the anterior cutting edge iscontinuous to the anteriorcusp, but a notch is present between them. The anteriorcuspis on the same plane with the anterior cutting edge. The posterior cutting edge isconcave and convex toward outside at the middle part. There are 29 serrations on theposterior cutting edge. There are 16 and 17 serrations within 10 mm distance on the

posterior cutting edge. A notch is present between the posterior cutting edge and theposterior cusp. The blade of the posterior edge is not continuous to the posterior cusp(Fig. 7E). The posterior cusp is not on the same plane with the posterior cutting edgeand slightly inclines inwards. The anterior cusp inclines to the front. There are 20serrations on the anterior cusp, 14 on the anterior edge and 5 on the posterior edge, withthe largest and the broadest one at the apex of the anterior cusp. Two large dents arepresent at the middle part of the anterior edge of the cusp and the others are about half ofthese in size. Five dents on the anterior end of the anterior cusp are minute. Theposterior cusp inclines to the rear. There are 15 serrations on the posterior cusp, 6ontheanterior edge and 8 on the posterior edge, with the largest and the broadest one at theapex of the posterior cusp. One large dent is present at the middle partof the posterioredge ofthe posterior cusp and the others are about halfofit insize. Two short ridges arepresent on the inner surface at the posterior end of the posterior cusp (Fig. 7E). Bothsurface of lateral cusps are equally convex, but the anterior cusp is thicker than theposterior one. The width of the crown is 34.5 mm. The thickness of the crown is 7.0mm and 20.3% of the crown width. The tooth neck is narrow. The maximum width ofthe neck is 0.6 mm and 1.7% ofthe crown width. The anterior and the posterior parts ofthe neck are black and these enamel layers are thick. The inner surface of the root isconvex and becomes more convex at the central part. The outer surface is flattish andslightly concave at the posterior part. The maximum thickness of the root is 8.5 mm atthe central part. The anterior and the posterior parts of the root are thin. Theconcavity of the root' s radial margin is the V shape.

KMNH VP 100,113. This specimen was collected from Hiroiwa, a rock locatednorthwest ofAinoshima Island, by the author (Fig. 8, PI. 1-3). This is a right upper jawtooth and is considered to be a lateral tooth. About half ofthe coronal part ofthe crownis missing. The central part of the inner surface of the crown baseis broken. The outersurface ofthe crown base is broken. Thecrown strongly inclines to the rear. The outersurface is flattish and slightly concave along the central axis just above the crown base.The narrow parts along both cutting edges are slightly concave. The blade of theanterior cutting edge is continuous to the anterior cusp, but a notch is present betweenthem (Fig. 8F). There are 10 serrations on the preserved anterior cutting edge whichlength is 7.1 mm. The posterior cutting edge curves inwards at the baseof the crown andis not continuous to the posterior cusp. There are 10 serrations on the preservedposterior cutting edge which length is 5.9 mm. The anterior cusp has 21 serrations, 8 on


Fig. 8. KMNH VP 100,113. A, outer surface; B; inner surface; C, anterior view; D,inner surface ofposterior cusp; F; inner surface ofanterior cusp. Scales 10 mm.

the anterior edge and 12 on the posterior edge, with the largest and the broadest one atthe apex of the anterior cusp. The anterior cusp is almost on the same plane with theanterior cutting edge of the crown (Fig. 8C, F). The posterior cusp has 20 serrations, 9on the anterior edge and 10 on the posterior edge, with the largest and the broadest one atthe apex. Two dents on the posterior end of the posterior cusp are minute. Theposterior cusp inclines inwards and is not on the same plane with the posterior cuttingedge of the crown (Fig. 8D, E). Both lateral cusps are equally convex on both sides.The anterior cusp is larger and broader than the posterior one. The width ofthe crownis 28.1 mm. The maximum thickness of the crown is 7.7 mm and 27.4% of the crownwidth. The maximum width of the tooth neck is 2.2 mm and 7.8% of the crown width.The inner surface of the root is convex. The convexity of the central part of the innersurface of the root is not significant. The outer surface of the root is slightly concave.The concavity of the root's radial margin is the V shape.

Ikeuchi's specimen 1. The specimen was collected from Kaijima Island by HideoIkeuchi (Fig. 9, Uyeno et al., 1984; pi. 1-1). This is a right upper jaw tooth and isconsidered to be a lateral tooth. The apex of the crown is broken and about 7mm ofboth cutting edges are missing. The coronal parts of both lateral cusps are missing.The serrations ofboth cutting edges are missing in several places. The crown is thin andinclines to the rear. The inner surface isconvex, butslightly concave at the central part.


Fig. 9. Ikeuchi's specimen 1. A, outer surface; B, inner surface; C, anterior view.Scale 10 mm.

The outer surface of the crown is slightly concave. The base of the crown is slightlyconvex at the anterior and the posterior parts of the outer surface. A low ridge is presenton the central part of the outer surface running from the base to the middle part of thecrown (Fig. 9A). The anterior cutting edge is slightly convex but becomes slightlyconcave inwards at the middle part(Fig.9C). The posterior cutting edge is almoststraight at the middle part and concave near the root. The posterior cutting edge isslightly convex inwards near the root. The blade of the posterior cutting edge is notcontinuous to the posterior cusp. The cervical endof the posterior cutting edge is locatedoutside the posterior cusp. Both cutting edges of the crown have 14 indentations within10mm distance. Both lateral cusp appear to be low and broad. The inner surfaces ofboth cusps are convex. The outer surfaces of both cusps are flattish. The posteriorcusps is thicker than the anterior one. The width of the crown is 48.0 mm. The

maximum thickness of the crown is 8.2 mm and 17.1% of the crown width. The

maximum width of the tooth neck is 3.5 mm and 7.3% of the crown width. The neck of

the tooth narrows at the base ofboth lateral cusps and is black along the coronal marginofthe neck. Theinner surface ofthe root isconvex. The convexity ofthe central partofthe inner surface ofthe root is not significant. The inner surface along the radial marginof the root is flattish. There is a small convexity near the posterior cusp on the root.The outer surface of the root is flattish, but the central part of the root along the neck ofthe tooth is slightly concave. The posterior part is broader than the anterior part of theroot. The concavity of the root's radial margin is the V shape.

Lower jaw teeth

The tooth is narrow and high. The crown stands erect or inclines to the rear. Theinner surface of the crown is convex. The outer surface is flattish. The outer surface of


the crown is slightly concave at the central part near the base of the crown and slightlyconvex near the apex of the crown. Serrations of both cutting edges are equal in size.The tooth neck is wider than that of the upper jaw tooth. The inner surface of the root isconvex. The convexity of the central part of the inner surface of the root is remarkable.The outer surface of the root is slightly concave or flattish. The concavity of the root'sradial margin is deeper than that of the upper jaw teeth. Nine specimens of lowerjaw

Fig. 10. Ikeuchi's specimen 2. A, outer surface; B, inner surface; C, anterior view;D, outersurface ofanterior cusp. Scales 10 mm.

Oligocene Lamnid Shark ofthe genus Carcharodon 253

teeth are described as follows.

Ikeuchi's specimen 2. This specimen was collected at Yoshida, Mizumaki-cho,Fukuoka Prefecture by Hideo Ikeuchi (Fig. 10, PI. 3-1). This is a left lower jaw tooth.The posterior part of the root and one sixth of the posterior part near the base of thecrown are missing. The serrations of the anterior cutting edge of the crown are broken inplaces. The serrations on the posterior cutting edge are almost completely preserved.The enamel surface of the base of the crown has deteriorated in several places. The

crown stands erect. The inner surface of the crown is prominently convex. The outer

surface of the crown is slightly convex and about one fifth of the central part from the base

to the apex of the crown is slightly concave (Fig. 10A). The central part of the outersurface of the crown is flattish at the middle part and is slightly convex near the apex.

The narrow part of the outer surface is slightly concave along the posterior cutting edge

and is flattish along the anterior cutting edge. Both cutting edges of the crown are almost

straight near the apex and slightly convex near the base. Both cutting edges of the crown

are convex outwards at middle parts and curve inwards near the apex. There are 67

serrations on the anterior cutting edge. The anterior cutting edge has 12 to 13

indentations within 10 mm distance. There are 63 serrations on the posterior cutting

edge. The posterior cutting edge has 12 to 14 indentations within 10 mm distance. The

anterior cusp has 23 serrations, 10 on the anterior edge and 12 on the posterior edge, with

the largest and the broadest one at the apex of the cusp. The dent on the apex and the

fourth dent from the anterior end are the largest. Both surfaces of the cusp are convex,

but the inner surface is more convex than the outer surface. The tooth neck is

remarkably wide but becomes increasingly narrower below the anterior cusp. The height

of the crown is 49.0 mm. The maximum thickness of the crown is 15.1 mm and 30.8% of

the crown height. The maximum width of the neck is 10.2 mm and 20.8% of the crown

height. The inner surface of the root is prominently convex and particularly convex atthe central part. The radial part of the inner surface is flattish at the center. The

anterior part of the root is relatively thin with thickness about half of the central part.The corner of the anterior part of the root is rounded. The concavity of the root's radialmargin appears to be round.

KMNH VP 100,092. The specimen was collected from Ainoshima Island byYoshihiko Okazaki (Fig. 11, Uyeno etal., 1984; pi. 3-1). This is a right lower jaw tooth.The apex of the crown is worn-out and about 1mm of both cutting edges are missing.Both cutting edges are broken in places. The posterior half of the anterior cusp and theanterior end of the posterior cusp are missing. The crown is thin. The crown standserect and curves outwards near the apex of the crown. The outer surface of the crown isflattish. The central part of the outer surface is slightly concave just above the crown

base and slightly convex near the apex. Both cutting edges of the crown are slightlyconvex near the apex and are slightly concave near the root. There are 61 serrations onthe anterior cutting edge. The anterior cutting edge has 12 to 18 indentations within 10mm distance. There are 50 serrations on the posterior cutting edge. The posterior


Fig. 11. KMNH VP 100,092. A, outer surface; B; inner surface; C, anterior view.Scale 10 mm.

cuttingedge has 13 to 15 indentations within 10mmdistance. There are 5 serrations onthe preserved anterior cusp. The dent of the posterior end is the largest among theremaining dents of the anterior cusp. The posterior cusp is highand inclines to the rear.There are 14serrations are the preserved posterior cusp, 4 on the anterior edge and 5 onthe posterior edge, with the largest one having four minute serrations located on theanterior margin at the apex of the posterior cusp. Both surfaces of lateral cusps areconvex, but the inner surfaces are more convex than the outer surfaces. The width of thecrown is 35.9 mm. The maximum thickness of the crown is 8.8 mm and 24.5% of the

crown width. The tooth neck is wide and the greatest width is 4.2 mm and 11.7% of thecrown width. The inner surface of the root is convex and particularly convex at thecentral part. The outer surface is slightly convex. The anterior part of the root isnarrow and extended. Both surfaces of the anterior part of the root are equally convex.The posterior part of the root is broad and both surfaces are equally convex. Thenutrientforamen is present at the central part of the innersurface of the root. There aretwo small foramina at the front of the nutrient foramen.

Kamei's specimen 2. This specimen was collected from Ainoshima Island byToshiyuki Kamei (Fig. 12, PI. 2-2). This is a left lower jaw tooth. The apex of thecrown is broken and about 2 mm of both cutting edgesare missing. The anterior part ofthe root and the radial half of the anterior cutting edge are broken and missing. Thecrown slightly inclines to the rear. The inner surface ofthe crown is convex, butflattishat the middle central part and flattish or slightly concave along both cutting edges. Theouter surface is flattish. The low ridgeis presentfrom the base up to the mid-central part


Fig. 12. Kamei's specimen 2. A, outer surface; B, inner surface; C, posterior view.Scale 10 mm.

ofthe outer surface ofthe crown. The central part ofthe outer surface isslightly convexnear the apex ofthe crown. The anterior part ofthe outer surface ofthe crown isslightlyconvex near the root. Both cutting edges of the crown are almost straight, but theanterior cutting edge curves to the rear near the apex. There are 35 serrations on thepreserved anterior cutting edge. The anterior cutting edge has 12 and 13 indentationswithin 10 mm distance. There are 67 serrations on the preserved posterior cutting edgewhere there are 14 to 16 indentations within 10 mm distance. The posterior cusp inclinesoutwards and has 14 serrations. There are 5 on the anterior edge and 8 (include 4minute dents near the root) on the posterior edge. The largest and the broadest one islocated at the apex of the posterior cusp. The tooth neck is remarkably wide. Themaximum width of the neck is 8.5 mm. The inner surface of the root is convex andparticularly convex at the central part. The posterior part of the root extends radially.The radial margin of the root is concave as rounded.

KMNH VP 100,090. The specimen was collected from Kaijima Island byYoshihiko Okazaki (Fig. 13, Uyeno et al., 1984; pi. 2-2). This is a right lowerjaw tooth.The anterior cusp and a part of the posterior cusp are missing. The apex of the crown isworn-out. The enamel surfaces have deteriorated along the base of the crown. Thecrown is thin. The crown stands erect. The inner surface of the crown is convex. The

outer surface of the crown is slightly concave along the central axis from the base to themiddle part of the crown and slightly convex near the apex. The anterior and the



posterior parts of the crown's outer surface are convex near the root. The anteriorcutting edge is slightly convex. There are 49 serrations on the anterior cutting edge.The anterior cutting edge has 11 and 12 indentations within 10 mm distance. Theposterior cutting edge is straight in outline. There are 54 serrations on the preservedposterior cutting edge. The posterior cutting edge has 11 and 12 indentations within 10mm distance. The posterior cusp has 10 indentations in existence. The outer surface ofthe posterior cusp is flattish. The inner surface of the cusp is convex. There is a shortridge near the root on the inner surface of the posterior cusp. The tooth neck isremarkably wide and maximum width is 7.1 mm. The neck narrows down at the base ofthe posterior cusp. The inner surface of the root is convex and particularly convex at thecentral part. The maximum thickness of the root is 16.4 mm. The anterior part of theroot extends radially. The outer surface of the root is flattish and is slightly concavealong the base of the crown. The posterior margin of the root is straight in outline. Theradial margin of the root is concave as rounded.

KMNH VP 100,116. The specimen was collected from Ainoshima Island byTakashi Okamoto and theauthor (Fig. 14, PI. 3-2). This isa left lower jaw tooth. Theposterior part of the root and the posterior cusp are missing. About 10 mm of the middlepart of the posterior cutting edge is broken. The apex of the anterior cusp is missing.The crown inclines to the rear. The inner surface of the crown is flattish at the centralpart. The outer surface is slightly convex atthe mid-central part near the root and alongboth cutting edges. The outer surface is slightly convex near the apex of the crown.The anterior part ofthe outer surface ofthe crown is convex near the root. The anterior



cutting edge is convex, but the basal part is concave and thin. There are 84 serrations on

the anterior cutting edge. The blade of the anterior cutting edge is continuous to theanterior cusp, but a notch is present. The posterior cutting edge is straight. There are44 serrations on the preserved posterior cutting edge. Both cutting edges have 12 to 14indentations within 10mm distance. There are 15indentation on the anterior cusp, 8 onthe anterior edge and 6 on the posterior edge, with the largest and the broadest one at theapex of the cusp. Both surfaces ol the anterior cusp are convex (Fig. 14C). The heightof the crown is 54.3 mm. The maximum thickness of the crown is 13.3 mm and 24.5% of

the crown height. The neck of the tooth is wide and greatest width is 6.9 mm and 12.7%of the crownheight. The tooth neck narrowerbehind the baseof the anterior cusp. Theinner surface of the root is convex and particularly convex at the central part. Themaximum thickness of the root is 20.0 mm. The anterior margin of the root is straight inoutline. A small convexity is present before the anterior end of the anterior cusp. Theouter surfaceof the root is slightlyconvex and the narrow part along the base of the crownis slightly concave. The radial margin of the root is concave as rounded.

KMNH VP 100,114. This specimen was collected from Kaijima Island byYoshihiko Okazaki (Fig. 15, PI. 2-1). This is a right lower jaw tooth. The coronal partof the crown and the anterior part of the root are missing. The crown stands erect. Theinner surface of the crown is convex, but flattish at the middle central part. The outer


Fig. 15. KMNH VP 100,114. A, outer surface; B; inner surface; C, posterior view.Scale 10 mm.

surfaceof the crown is flattish, but slightly convex at the central part. The outer surfaceis slightly concave along thecentral axis just above thecrown base and along bothcuttingedges. The maximum thickness of the crown is 8.8 mm. The anterior cutting edge isalmost straight. There are 35 serrations on the anterior cutting edge. The anteriorcutting edge has 16 and 17 indentations within 10 mm distance. The posterior cuttingedge is slightly concave and curves inwards near the base of the crown. There are 27serrations on the posterior cutting edge. The posterior cutting edge has 13 to 14indentations within 10 mm distance. The blade of the posterior cutting edge appear to

be not continuous to the posterior cusp, although a short part between the posteriorcutting edge and the posterior cusp is missing. The posterior cusp is broken in places.There are 10indentations on the posterior cusp in existence, 4 on the anterior edgeand 5on the posterior edge, with the largest and the broadest one at the apex ofthe cusp. Thedent near the apex onthe posterior edge ofthe cusp is the second largest. Both surface ofthe posterior cusp are convex. The inner surface of the cusp is more convex than theouter one. The neck of the tooth is wide and the maximum width is 4.5 mm. The neckof the tooth narrows rapidly near the anterior end of the posterior cusp. The neck isblack along its coronal margin. The root is wide. The inner surface of the root isconvex. There is a small convexity near the posterior cusp. The posterior part of theroot is thin. Both surfaces of the posterior part of the root are flattish. The concavity ofthe root's radial margin appears to be rounded.

Ikeuchi's specimen 3. This specimen was collected from Kaijima Island by HideoIkeuchi (Fig. 16, PI. 2-3). This is a left lower jaw tooth. The apex of the crown isbroken. About 10 mm of the posterior cutting edge and about 20 mm of the anteriorcutting edge are missing. The posterior part ofthe root is missing. The dents on both


Fig. 16. Ikeuchi's specimen 3. A, outer surface; B, inner surface; C, anterior view.Scale 10 mm.

cutting edges are missing in several places. The crown slightly inclines to the rear. The

inner surface of the crown is convex, but flattish at the middle central part. The outer

surface is slightly concave along the central axis from the base to the middle part of the

crown. The anterior and posterior parts of the outer surface are slightly convex. The

central part of the outer surface near the apex is slightly convex. The anterior cutting

edge is nearly straight. There are 41 serrations on the anterior cutting edge. The

anterior cutting edge has 13 and 14 indentations within 10 mm distance. The blade of

the anterior cutting edge is continuous to the anterior cusp, but a notch is present between

them. The posterior cutting edge is straight in outline. There are 57 serrations on the

posterior cutting edge. The posterior cutting edge has 13 to 15 indentations within 10

mm distance. The blade of the posterior cutting edge is not continuous to the posteriorcusp. The cervical end of the posterior cutting edge is located at the outside of the

posterior cusp. The anterior cusp is broad. The anterior cusp has 18 serrations, 12 on

the anterior edge and 5 on the posterioredge, with the largest and the broadest one on theapex of the anterior cusp. The four serrations on the anterior edge near the root of theanterior cusp are minute. The posterior cusp has 15 serrations, 6 on the anterior edge

and 8 on the posterior edge, with the largest and the broadest one at the apex of the

posterior cusp. Both lateral cusps are thin. Both surfaces of lateral cusps are convex,but the inner surfaces are more convex than the outer surfaces. The tooth neck is

remarkably wide and the maximum width is 6.4 mm. The tooth neck narrows graduallyclose to the posterior and the anterior ends. The inner surface of the root is convex.

The convexity of the central part of the root is not remarkable. The outer surface is

slightly convex. The anterior part of the root extends and curves outwards. The

260

Fig. 17. KMNH VP 100,115.Scale 10 mm.

Yoshitaka Yabumoto

A, outer surface; B; inner surface; C, anterior view.

concavity of the root's radial margin is rounded.

KMNH VP 100,115. This specimen was collected from Sakamizu, Wakamatsu-ku,

Kitakyushu City by Koichi Mukaibo (Fig. 17, PI. 1-5). This is a left lower jaw tooth.

The apex of the crown is broken. About 5 mm of the anterior cutting edge and the half of

the posterior cutting edge near the apex are missing. The serrations of both cutting edges

are missing in several places. The posterior and the anterior cusps are missing. The

root is entirely broken and missing. The specimen is small in size. The crown is thin

and slightly inclines to the rear. The inner surface of the crown is convex, but flattish at

the mid-central part. The outer surface of the crown is slightly convex and more convex

near the base of the crown. There is a low ridge at the central part near the apex of the

crown on the outer surface. The anterior cutting edge is slightly convex near the apex

and slightly concave near the root. In the anterior view, the anterior cutting edge is

almost straight (Fig. 17C). There are 45 serrations on the preserved anterior cutting

edge. The anterior cutting edge has 17 and 18 indentations within 10 mm distance.

The posterior cutting edge is straight in outline and slightly curves outwards near the root.

There are 20 serrations on the preserved posterior cutting edge. The posterior cutting

edge has 16 indentations within 10 mm distance. The tooth neck is wide at the central

part and the greatest width is 3.1 mm.

KMNH VP 100,091. This specimen was collected from Kaijima Island byYoshihiko Okazaki (Fig. 18, Uyeno el al., 1984; pi. 2-3). This is a left lower jaw tooth.The apex of the crown is broken and about 8 mm of both cutting edges are missing.

Oligocene Lamnid Shark ofthe genus Carcharodo 261

Fig. 18. KMNH VP 100,091. A, outer surface; B; inner surface; C, anterior view.Scale 10mm.

About 5mm of the middle part of the posterior cutting edge is missing. Both lateralcusps and the root are missing. The crown inclines to the rear. The outer surface ofthecrown is slightly convex. A low ridge is present along the central axis from the base tothe middle of the outer surface of the crown. The anterior cutting edge is straight inoutline. There are 39 serrations on the anterior cutting edge. The anterior cutting edgehas 14 and 15 indentations within 10 mm distance. The posterior cutting edge is almoststraight, but concave and curves outwards near the root. There are 28 serrations on theposterior cutting edge. The posterior cutting edge has about 12 indentations within 10mm distance. The width ofthe tooth neck is moderate and the maximum width is 3.0mm.

Concluding Remarks

There is a wide variation in size, thickness, inclination and number of serrations onthe crown, lateral cusps, tooth neck and a shape of the root among teeth of Carcharodonangustidens from the Ashiya Group. The variations of these characters indicate positionson jaws and an individual differences.

The small specimens, KMNH VP 100,112 and 100,113, are considered to be lateralteeth on the upper jaws, and their crown incline to the rear. These specimens are similarto each other, but the lateral cusps, the tooth neck and root show differences. Thesespecimens are similar to figures of Carcharias helerodon and Carcharias megalotis which aredescribed by Agassiz (1833-45), but I consider that the figures of C. heterodon and C.megalotis by Agassiz are based on posterior lateral teeth of Carcharodon angustidents Thespecimen, KMNH VP 100,093 (Fig. 4, Uyeno et al., 1984: pi. 3-3) and Kamei's specimen


1, (Fig. 3, Uyeno et al., 1984: pi. 3-2) are considered to be anterior teeth on upper jaws,because their crowns stand erect. The specimen, KMNH VP 100,093, is considered tobe a tooth of a small individual, because it is the smallest in size among specimensexamined. This specimen is characterized that the outer surface is convex. Yamaoka'sspecimen 1(Fig. 6, PI. 1-4), Kida's specimen 1(Fig. 5, PI. 1-1) and Ikeuchi's specimen 1(Fig. 9, Uyeno et al., 1984: pi. 2-1) are lateral teeth on upper jaws. The specimens ofYamaoka and Kida are similar to each other excepting lateral cusps. The crown ofIkeuchi's specimen 1 is thin and wide. The specimen is probably transformed afterdeposition. Ikeuchi's specimen 2(Fig. 10, PI. 3-1) is considered to be an anterior toothon the lower jaw, because the crown stands erect and is thick. The cusp of this specimenis not continuous to the cutting edge ofthe crown. The specimen ofKMNH VP 100,090(Figs. 13, Uyeno et al, 1984: pi. 2-2) and KMNH VP 100,116 (Fig. 14, PI. 3-2) areconsidered to be lateral teeth on lower jaws because ofthese crowns slightly inclined to therear. The crowns of these specimens are wider and thinner than that of the anteriortooth of Ikeuchi's specimen 2 (Fig. 10). The crown of KMNH VP 100,116 more inclinesto the rear than that ofKMNH VP 100,090. Ikeuchi's specimen 3 (Fig. 16 PI. 2-3) is alateral tooth, because the crown inclines to the rear. In this specimen, both lateral cuspsare wide and low, and the blades ofthe both cutting edges'are continuous to lateral cusps.The specimen, KMNH VP 100,115 (Fig. 17, Pl> 1^5) is considered to be alateral tooth ona lower jaw, because the crown inclines to the rear and has a wide tooth neck. Thisspecimen is considered to be atooth of asmall individual. These lower jaw teeth have awide tooth neck and a height crown.

Casier (1960) suggested that Carcharodon auriculatus ultimately evolved into C.angustidens. Welton and Zinsmeister (1980) considered that C. auriculatus ranged fromEocene to Oligocene, mainly Eocene and C. angustidens ranged from Oligocene to LowerMiocene. Case (1980, 1981) and Fowler (1911) considered that C. angustidents is asynonym for C. auriculatus. But Welton and Zinsmeister (1980) described the differencebetween C. auriculatus and C. angustidens (C. auriculatus has higher and narrower crownedanterior teeth comparing to C. angustidens). The anterior tooth from Kitakyushu(Ikeuchi's specimen 2) has lower and wider crown comparing to specimens of C. auriculatusreported by Welton and Zinsmeister (1980).

These variation in the tooth of the upper and lower jaws from Kitakyushu are similarto the fossil teeth of Carcharodon auriculatus, which included C. angustidents as a synonym,from the beds of Late Eocene of South-Central Georgia (Case, 1981), Lower Miocene ofeastern North Carolina in North America (Case, 1980) and Cretaceous, Eocene andMiocene in North America (Fowler, 1911). Carcharodon cfr. turgidus has been reportedfrom Kyushu by Nagao (1928). The specimens of Nagao (1928) are considered to be C.angustidens.

Casier (1960) deduced that the fossil species of Carcharodon could be divided into twogenera, Procarcharodon and Carcharodon, and the modern Carcharodon derived from earlyIsurus hastalis, and recognized aseparate lineage for the remaining species of Procarcharodon.


But here I tentativelyagree with Keyes (1972) and Welton and Zinsmeister (1980) thatthe similarities between /. hastaris and Carcharodon might be indication of convergencerather than phylogenetic relationship.

Literature Cited

Agassiz, L. 1833-45. Recherches sur les poissons fossiles. 3.Appleoate, S. P. 1965. Tooth terminolgy and variation in sharks with special reference to the sand

shark, Carcharias taurus Rafinesque. Los Angeles County Museum, Contrib. Set., 86: 3-18, figs. 1-5.Cappetta, H. 1970. Les selaciens du Miocene de la region de Montpellier. Palaeovertebrata, Memoir

Etraordinaire: 1-139, 27 pis.

Case, G. R. 1980. A selachian fauna from the Trent Formation, Lower Miocene (Aquitanian) ofeastern North Carolina. Palaeontographica Abt. A, 171: 75-103, figs. 1-6, pis. 1-10.

Case, G. R. 1981. Late Eocene selachians from South-Central Georgia. Palaeontographica, Abt A176:52-79, figs. 1-9, pis. 1-9.

Casier, E. 1960. Note sur la collection des Poissons Paleocene et Eocenes de I'Enclave de Cabinda(Congo) recueillis par J. Bequaert au cours de sa mission en 1913. Ann. Mm. roy. Congo BelsSer. 31, (2): 1-48. '

Fowler, H. W. 1911. A description of the fossil fish remains of the Cretaceous, Eocene, andMiocene formations ofNew Jersey. Bull. Geol. Surv. New Jersey, 4: 22-182.

Goto, M. 1972. Fossil Chondrichthyes ofJapan. J. Geol. Soc. Japan, 78 (11): 585-600.Hirayama, K. 1956. Tertiary Mollusca from Hikoshima, Yamaguchi Prefecture, Japan, with

remarks on the geological age ofthe "Ashiya Fauna". Sci. Rep. Tokyo Kyoiku Daigaku, Sec C 5(45): 81-127, fig. 1, pis.6-8.

Keyes, I. W. 1972. New records ofthe elasmobranch C. megatodon (Agassiz) and a review ofthegenus Carcharodon in the New Zealand fossil record. N. Z.Jour. Geol. Geophys. 15 (2)- 229-242

Matsushita, H. 1949. Geology ofthe coal fields in northern Kyushu. J. Mining Inst., Kyushu, SbecPaper, 57 pp., figs. 1-8.

Matsushita, H. 1969. Geological map of Kitakyushu City. Kitakyushu City.Mizuno, A. 1963. Paleogene and Lower Neogene biochronology of West Japan. (III. Stratigraphic

and Geographic distributions of molluscan faunas in West Japan). /. Geol. Soc. laban 69(808): 38-58, figs. 1-2.

Murata, S. and T. Mokudai. 1959. Paleogene stratigraphy in Ainoshima, Kokura City, KyushuBull. Kyushu Inst. Tech. (M. &N. S.), (5): 49-57, figs. 1-3.

Nagao, T. 1927. Palaeogene fossils of the Island of Kyushu, Japan. Part II. Sci. Rep. Tohoku ImpUniv., 2nd Ser., 12( 1): 11 -140, 17 pis.

Uyeno, T. 1975. Pisces, pp. 181-242. In Shikama, T., (ed.), Paleontology, III, Asakurashoten,Tokyo, iv+7+527 pp.

Uyeno, T and Y. Hasegawa. 1974. A new Miocene lamnoid shark, Carcharodon akitaensis, fromCentral Japan. Bull. Natn. Sci. Mas. Tokyo, 17 (3): 257-260, figs. 1-3, pi. 1.

Uyeno, T., Y. Hasegawa and T. Kakuta. 1980. Some shark teeth'from Miocene IchishiFormation in Mic Prefecture, Japan. Bull. Natn. Sci. Mus. Ser. C(Geol.) 6(4): 125-128, pis. 1-2

Uyeno, T., Y. Hasegawa, T. Nohara, and A. Adaniya. 1974. A fossil shark tooth ofCarcharodonmegalodon from Miyako-jima. (Studies of the palaeovertebrate fauna of Ryukyu Islands, Japanpart V.). Mem. Natn. Sci. Mus., 7: 61-64, figs. 1-2.

Uyeno, T., Y. Yabumoto and N. Kuga. 1984. Fossil fishes of Ashiya group-(I). Late OligoceneElasmobranchs from Islands of Ainoshima and Kaijima, Kitakyushu. Bull Kitakyushu Mus.


Nat. Hist., 5: 135-142, pis. 1-5.Welton, B.J. and W.J. Zinsmeister. 1980. Eocene neoselachians from the La Meseta Formation,

Seymour Island, Antarctic Peninsula. Los Angeles County Museum, Contrib. Sci., 329: I-10, figs.1-4.

Oligocene Lamnid Shark of the genusCarcharodon from Kitakyushu, Japan.

Yoshitaka Yabumoto

Plates 1-4

Explanation of Plate 1.


1. Kida's specimen 1. Right upper jaw tooth; a, outer surface; b,inner surface; c, anterior view. X 1

2. KMNH VP 100,112. Left upper jaw tooth; a, outer surface; b,inner surface; c, anterior view. X 1

3. KMNH VP 100,113. Right upper jaw tooth; a, outer surface; b,inner surface; c, anterior view. X 1

4. Okayama's specimen 1. Inner surface ofthe right upper jaw tooth.X 1

5. KMNH VP 100,115. Left lower jaw tooth; a, outer surface; b,inner surface; c, anterior view. X 1

Yabumoto, Y. Oligocene Lamnid Shark of the genus Carcharodon Plate 1

Plate 2



1. KMNH VP 100,114. Right lower jaw tooth; a, outer surface; b,inner surface; c, posterior view. X 1

2. Kamei's specimen 2. Left lower jaw tooth; a, outer surface; b,inner surface; c, posterior view. X 1

3. Ikeuchi's specimen 3. Left lower jaw tooth; a, outer surface; b,inner surface; c, anterior view. X 1

PlateS



1. Ikeuchi's specimen 2. Left lower jaw tooth; a, outer surface; b,inner surface; c, anterior view. X 1

2. KMNH VP 100,116. Left lower jaw tooth; a, outer surface; b,inner surface; c, anterior view. X 1

Plate 4



1. Inner surface of posterior cusp. Okayama's specimen 1. X4.22. Inner surface of anterior cusp. Okayama's specimen 1. X4.23. Outer surface of anterior cusp. Kida's specimen 1. X4.84. Outer surface of posterior cusp. Kida's specimen 1. X5.35. Inner surface of anterior cusp. Ikeuchi's specimen 2. X3.46. Outer surface of posterior cusp. KMNH VP 100,112. X5.57. Outer surface of anterior cusp. KMNH VP 100,113. X5.88. Outer surface of posterior cusp. KMNH VP 100,113. X5.8

bull. kitakyushu mus. nat. hist., 6: 239-264.march …...fossil teeth of the genus carcharodon have...

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