Middle and Late Pleistocene Wild Boar Remains from ...
Transcript of Middle and Late Pleistocene Wild Boar Remains from ...
第 四 紀 研 究(The Quaternary Research) 40 (2) p. 149-160 April 2001
Middle and Late Pleistocene Wild Boar Remains from Locality 1 of Ube
Kosan Quarry in Yamaguchi Prefecture and from the Kannondo
Cave Site in Hiroshima Prefecture, Western Japan
Masakatsu Fujita*1 and Yoshinari Kawamura*2
A systematic description is given to a Middle Pleistocene remain (M3) from Locality 1 of Ube Kosan Quarry, and three Late Pleistocene remains (frontal bone, I2 and P4) from the Kannondo cave site. These remains are important to elucidate morpholog-ical characters of wild boars inhabited the mainland of Japan during the Pleistocene, because wild boar remains dated certainly as the Pleistocene are quite limited in Japan. The remains are compared with the living and Quaternary fossil suid species known from East Asia. The morphological characters of the remains are mostly coincident with those of Sus scrofa, an extant species now widely distributed inEurasia, but the exact identification is left pending owing to the insufficiency of the morphological data of the fossil species as well as the poor preservation of the present remains. The remains are therefore assigned to S. cf. scrofa. As regards the size of the remains, the M3 is larger than that of S. scrofa leucomystax, an extant subspecies of S. scrofa now distributed in Honshu-Shikoku-Kyushu, but is approximately as large as those of S. scrofa from other Middle Pleistocene localities. The other three remains are approximately as large as S. s. leucomystax. On the basis of the present study as well as the data so far obtained, it is inferred that the wild boar of S. scrofa or its allied form already inhabited Honshu-Shikoku-Kyushu in the middle Middle Pleistocene, and then decreased toward the Late Pleistocene. From the late Late Pleistocene to Holocene, it increased drastically, and became a dominant artiodactyl in the Holocene fauna of Honshu-Shikoku-Kyushu.
Key words: Middle Pleistocene, Late Pleistocene, wild boar, Ube Kosan Quarry,
Kannondo cave site, Japan
I. Introduction
Our knowledge on Pleistocene wild boars has been fragmented in Japan, owing to the scant-iness of fossil material. Until recently, wild boar remains dated as the Pleistocene had been almost limited to those from Tsukinoki in Akita Prefecture (Matsumoto 1915a, b, 1916; Tokunaga, 1927; Naora, 1944), Yoshizawa Quarry in Tochigi Prefecture (Shikama, 1933, 1937a, b, c, 1949; Naora, 1944, 1954), the Kannondo cave site in Hiroshima Prefecture
(Kawamura, 1980, 1992, 1995), Locality 1 of
Ube Kosan Quarry in Yamaguchi Prefecture
(Kawamura, 1988), and Matsugae Cave in Fukuoka Prefecture (Tokunaga, 1930; Naora, 1944, 1954), which are shown in Figure 1. Of the remains, those from Tsukinoki and Yoshizawa
Quarry were described systematically by Matsumoto (1915a) and Shikama (1949), respec-tively. But no systematic description was
given to the remains from Matsugae Cave, which were possibly lost during the World War II. On the other hand, the remains from the Kannondo cave site and Locality 1 of Ube Kosan Quarry were obtained in relatively
Received June 5, 2000, Accepted October 28, 2000. *1 Graduate School of Science
, Osaka City University. 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka, 558-8585, Japan.
E-mail:*2 Department of Earth Sciences
, Aichi University of Education. 1 Hirosawa, Igaya-cho, Kariya, 448-8542, Japan.
150 M. Fujita and Y. Kawamura April 2001
Fig. 1 Pleistocene fossil localities of wild boars in
the mainland of Japan
recent years, but their systematic descriptions have not been published so far.
Recent excavations of the Middle Pleistocene sediments of NT Cave produced rich wild boar remains which were systematically described in detail by Fujita et al. (2000) in the course of our studies on Quaternary wild boars of Japan and the adjacent areas. In the same coause, we here attempt to provide a systematic descrip-tion of the remains from Locality 1 of Ube Kosan Quarry and the Kannondo cave site. The remains are quite limited in number and
poor in preservation, but their systematic de-scription is expected to supplement important knowledge to the Pleistocene wild boars in Japan.
II. Fossil locality
Ube Kosan Quarry is a large limestone
quarry in Isa Cement Plant of Ube Kosan Com-
pany, which is situated at Isa, Mine City, Yamaguchi Prefecture. Fossil localities yield-ing Quaternary mammals have been occasion-
ally found in the quarry by the advance of limestone quarrying (Shikama and Okafuji, 1958, 1963; Shikama et al., 1967; Okafuji, 1971; Kawamura, 1988). Locality 1 named by Kawa-mura (1981) is one of the fossil localities, in which Pleistocene fossiliferous cave sediments were exposed. The stratigraphic sequence of the sediments and the f aunal list of the mam-mals obtained were given in Kawamura (1988), and all the sediments are considered to be of late Middle Pleistocene age (Kawamura, 1988, 1991; Kawamura et al., 1989). The wild boar remain described herein was obtained from the lowest part of the sediments (Layer 4b; vide Fig. 6 of Kawamura, 1988). The Kannondo cave site is located at
Nagano, Jinseki, Hiroshima Prefecture. This
site is one of the largest and most important
sites in the limestone cave and rockshelter sites collectively called the Taishaku-kyo sites dis-
tributed mainly along the gorge of the Taishaku River. Over 30 years' excavations
of the site have revealed that the upper part
of the sediments yields abundant artifacts, human bones and vertebrate remains of
Holocene age, while the lower part dated as the
Late Pleistocene produces abundant vertebrateremains, but lacks evident signs of humans. The stratigraphic sequence of the sediments and the disposition of the excavation grids are summarized in Kawamura (1988). In the upper
part of the sediments (Holocene horizons), wild boar remains are abundant, but they are very scarce and restricted to Horizon N and Horizon 0 (upper part) in the lower part (Late Pleisto-cene horizons), as already pointed out by Kawamura (1992). These horizons are approxi-mately dated between 20 and 40 ka (vide Fig. 2 of Kawamura, 1992).
III. Terminology and measuring method
The terminology of the skull and teeth a-dopted here is given in Figure 2. For the cusp terminology of the cheek teeth, we mainly follow Made (1996). The tooth measurements are taken parallel or perpendicular to the base line (BL) as shown in Figure 2. As regards the measurements, the following abbreviations are used: Lhp: Length from the menial surface of the
2001年4月 Pleistocene wild boar remains from western Japan 151
Fig. 2 Terminology and measuring method for describing the present wild boar remains
For the abbreviations see text.
hypopreconulid to the distal surface of the
pentapreconulid in M3. LLD: Labiolingual diameter of the crown
in I2, measured at 2mm above the lingual cervix, which is measurable in the I2 described here. Wa: Width of M3 between the buccal sur-face of the protoconid and the lingual surface of the metaconid. In the M3 described here, Wa is estimated from Wm by the regression line shown in Figure 6.
Wm: Width of M3 between the buccal sur-face of the hypoconid and the lingual surface of the entoconid, which is the same as the middle width of the crown by Fujita et al.
(2000).
IV. Systematic description
Order Artiodactyla Owen, 1848
Family Suidae Gray, 1821 Subfamily Suinae Zittel, 1893
Genus Sus Linnaeus, 1758
Sus cf. scrofa Linnaeus, 1758
(Figs. 3-5) Material-
Locality 1 of Ube Kosan Quarry: 1 fragmental left M3 from Layer 4b (ASM
703374) stored in the Akiyoshi-dai Museum of Natural History (listed in p. 102 of Kawamura, 1988). Kannondo cave site (Late Pleistocene hori-
zons): 1 skull fragment (right frontal bone) from
Horizon N (Layer 24-B in Grid J) numbered HUA-K04160 (listed in p. 68 of Kawamura, 1980)
;1 left I2 from Horizon N (Layer 24 in Grid HE) numbered HUA-K04161 (listed in p. 123 of Kawamura, 1995); 1 fragmental left P4 from the upper part of Horizon O (Layer 25-B in Grid
J) numbered HUA-K04162 (listed in p. 68 of Kawamura,1980). All the specimens are stored in the Department of Archaeology, Faculty of Letters, Hiroshima University.1)
Description
Skull-
The skull is represented only by a right fron-
152 M. Fujita and Y. Kawamura April 2001
tal bone from the Kannondo cave site (HUA-K 04160; Fig. 3). The frontonasal, frontolacrimal and coronal sutures form the anterior, ante-rolateral and posterior margins of the speci-men respectively, where the striated vertical surfaces of the sutures are observed. This sug-
gests that the nasal, lacrimal and parietal bones were easily removed from the frontal bone along the sutures, and thus the frontal bone belongs to a relatively young individual.
In lateral view, the dorsal surface of the ex-ternal plate of the frontal bone gently curves upward, and the orbital margin preserved is a circular arc (Fig. 3, B). The wall of the orbit forms a smooth spherical surface. In dorsal view, the external plate of the frontal bone is smooth except in its anteromedial part, where a shallow groove runs parallel to the lateral margin of the bone from the position of the supraorbital foramen whose dorsal wall is broken away (Fig. 3, A). The internal surface of the internal plate of the frontal bone is wrinkled. As a whole, the morphology and size of the orbit, the external and internal plates and the frontal sinuses between the plates are almost equal to those of the living S. scrofa leuco-mystax compared.
I2- I2 is represented only by HUA-K04161 from
the Kannondo cave site (Fig. 4, la-c). The crown is strongly worn, so that its lingual sur-face becomes only 1-2mm in height. Its labial surface, relatively well preserved, is smooth and weakly inflated. The occlusal surface forms a flat wear facet with a narrowly ellipti-cal occlusal outline (Fig. 4, 1b). The enamel exposed on the facet measures 0.6mm to 1.2 mm in thickness. The cervix is almost straight on the lingual surface, while it is remarkably undulated on the labial surface. A stout root is observed above the cervix. It extends dorso-distally, although its apical part is lost. The cross section of the root is elliptical at its broken end. No longitudinal grooves are ob-served on both labial and lingual surfaces of
the root. LLD measures 5.0mm. P4-
P4 is represented only by HUA-K04162 from the Kannondo cave site, which preserves the linguodistal part of the crown and the distal root (Fig. 4, 2a, b). The metaconid and hypo-conid form the distal part of a high cutting edge, which descends distally. The lingual sur-face of the crown is weakly concave between these cusps to form a shallow vertical valley. A small accessory cusp is attached on the distal surface of the hypoconid. The cusp is slightly lower than the hypoconid. A furrow between the cusp and hypoconid is short, but clearly observed. This furrow is blocked lingually byanother small accessory cusp, which is much
lower than the hypoconid. In lateral view, the
posterior margin of the crown steeply inclines
mesially. The cervix is nearly straight and
gently inclines mesially. The root is much
longer than the height of the crown preserved.
It extends straight ventrally, and tapers
apically. Its cross section is broadly elliptical.
M3- M3 is represented only by ASM703374 from
Locality 1 of Ube Kosan Quarry, which pre-serves the middle part of the crown (Fig. 5). The width of the crown decreases distally (Fig. 5, A). All the cusps preserved are unworn, but the enamel thickness is measurable on the ven-tral broken surface of the tooth. It ranges from 0.9mm to 1.8mm.
Of the cusps preserved, the hypopreconulid
is slightly lower and much smaller than the
entoconid which has nearly the same size and
height as the hypoconid. In occlusal view, the
hypopreconulid shows an elliptical outline
elongated transversely, and is situated relative-
ly buccal to the median line of the crown. Two
fine vertical furrows are observed on the lin-
gual and buccal surfaces of the cusp, respec-
tively. A narrow transverse groove separates
the hypopreconulid from the entoconid and
hypoconid. The lingual part of the groove is
deeper and more distinct than its buccal part.
The entoconid and hypoconid are conical,
1) In addition to these three specimens, Kawamura (1995) listed a canine fragment of Sus scrofa from the upper part of Horizon O in his Table 5 (p. 123). Our revision, however, has revealed that the fragment
does not belong to S. scrofa, but is probably assignable to a bear canine.
2001年4月 Pleistocene wild boar remains from western Japan 153
Fig. 3 Sus cf. scrofa from the Late Pleistocene horizons of the Kannondo cave site
Skull fragment numbered HUA-K04160.
Fig. 4 Sus cf. scrofa from the Late Pleistocene
horizons of the Kannondo cave site
154 M. Fujita and Y. Kawamura April 2001
Fig. 6 Relationship between Wa and Wm in the
living Sus scrofa leucomystax from Honshu.
A regression line (Wa=0.9597 Wm+1.4254)
is obtained in order to estimate Wa from
Wm in the M3 from Locality 1 of Ube
Kosan Quarry.
Fig. 5 Left M3 of Sus cf. scrofa from Locality 1 of
Ube Kosan Quarry (ASM703374)
and are opposite in position. They are sepa-
rated from each other by a central longitudinal
groove, which meets the transverse groove at
its mesial end. On the mesiobuccal surface of
the entoconid, there is a fine vertical furrow
which has a branch extending distobuccally. A
short vertical furrow is also observed on the
buccal surface of the entoconid and on the
lingual surface of the hypoconid, respectively.
The furrow on the buccal surface of the en-
toconid has a long branch extending mesio-
lingually. Furthermore, a longer vertical
groove is observed on the distal surface of the
entoconid and on the distal surface of the
hypoconid, respectively. The groove on the
distal surface of the hypoconid bifurcates near
the apex of the cusp. There is no cingulum on
the lingual surface of the entoconid and on the
buccal surface of the hypoconid.
The central longitudinal groove bifurcates
distally; one branch extends distobuccally,
while another extends distolingually. These
branches separate the pentapreconulid from
the hypoconid and entoconid. The penta-
preconulid is elliptical in occlusal view, and is considerably lower and smaller than the hypoconid and entoconid. The pentaectoconu-lid is attached on the buccal surface of the
pentapreconulid. This cusp is much smaller and lower than the pentapreconulid. Further-more, a very small accessory cusp is attached on the mesiobuccal base of the pentaectoco-nulid (Fig. 5, A, B). On the other hand, a cusp corresponding to the pentaectoconulid is ob-served on the lingual surface of the penta-
preconulid. This cusp has almost the same size and height as the pentaectoconulid. Addition-ally, two small indistinct accessory cusps are attached on its lingual base (Fig. 5, C). Lhp and Wm measure 16.3mm and 17.9mm,
respectively. Wa is estimated as 18.5mm from the regression line shown in Figure 6.
Comparison We compare the present fossil specimens
with the living and Quaternary fossil suid spe-cies known from East Asia. As regards the living suids of the Palaearctic and Oriental Regions, their taxonomy was recently revised by Corbet (1978), Groves (1981), and Corbet and Hill (1992). According to these authors, only one species of suids, S. scrofa, is now dis-tributed in East Asia. This species contains six East Asian subspecies, such as S. s. leucomystax
2001年4月 Pleistocene wild boar remains from western Japan 155
in the mainland of Japan (Honshu-Shikoku-Kyushu; excluding Hokkaido), S. s. riukiuanus in the Ryukyu Islands, S. s. ussuricus (=S. s.
gigas) in northeast China, Korea and Far East Russia, S. s. sibiricus in Transbaikalia and northern Mongolia, S. s. moupinensis from North and South China and S. s. taivanus in Taiwan (Groves, 1981). On the other hand, the following Quaternary fossil species have been recorded from East Asia.
Potamochoerus nodosarius Han (from Gigan- topithecus Cave, Liucheng, Guangxi, south- ern China; Early Pleistocene)
Dichoryphochoerus ultimus Han (ditto) Sus liuchengensis Han (ditto) S. australis Han (ditto) S. peii Han (ditto) S. xiaozhu Han, Xu et Yi (from Giganto-
pithecus Cave, and from Bijiashan, Liu- zhou, Guangxi, southern China; Early
Pleistocene)S. bijiashanensis Han, Xu et Yi (ditto) S. subtriquetra Xue (from Weinan, Shaanxi,
northern China; Early Pleistocene) S. lydekkeri Zdansky (from many fossil
localities of Early and Middle Pleistocene age in northern China)
Among these fossil species, S. subtriquetra was described on the basis of a pair of dentaries with canine, and one worn M2 only (Xue, 1981). This species is, therefore, impossible to com-
pare with the present fossil specimens. The remaining species except S. lydekkeri are
compared with the present fossil specimens on the basis of the descriptions and figures of Han et al. (1975) and Han (1987), because we could not observe the specimens of these species di-rectly in the Institute of Vertebrate Paleontolo-
gy and Paleoanthropology, Academia Sinica, and because these papers are the only data sources which provide us morphological char-acters of the species. On the other hand, we could observe many specimens of S. lydekkeri in the same institute. Thus our comparison with S. lydekkeri is based upon the direct obser-vation as well as the descriptions and figures of Zdansky (1928) and Young (1932). Of the fossil species listed above, Potamo-
choerus nodosarius and Dichoryphochoerus
ultimus are problematic in their generic alloca-
tion, judging from the recent revision of fossil suids in the Indian Subcontinent (Pickford, 1988). But we use Han's original allocation here, because we did not observe their speci-mens and their generic allocation is not the aim of this paper. On the other hand, the taxonom-ic position of S. lydekkeri was discussed by Fujita et al. (2000) who considered it as a chron-ological subspecies of S. scrofa, because its characters are accommodated in the range of variation of S. scrofa, judging from the recent taxonomical concept of S. scrofa (Corbet, 1978; Groves, 1981; Corbet and Hill, 1992). We here follow Fujita et al. (2000), and treat S. lydekkeri as S. scrofa lydekkeri. Among the fossil specimens described here, the skull from the Kannondo cave site is com-
parable with that of the living S. scrofa leucomystax from Honshu as well as those of S. scrofa from the Middle Pleistocene of NT Cave, S. scrofa lydekkeri from the Middle Pleistocene of Locality 1 of Zhoukoudian and P. nodosarius from the Lower Pleistocene of Gigantopithecus Cave. The comparisons with D. ultimus, S. liuchengensis, S. australis, S. peii, S. xiaozhu and S. bijiashanensis are, however, impossible, be-cause the morphology of their skulls is un-known (vide Han et al., 1975; Han,1987). The present skull is very similar to that of S.
scrofa leucomystax in size and shape. It is also similar to S. scrofa from NT Cave and S. s. lydekkeri from Locality 1 of Zhoukoudian, but is considerably smaller than these two. On the other hand, the skull of P. nodosarius is differ-ent from the present skull in having the exter-nal plate of the frontal bone steeply elevated
posteriorly and the supraorbital foramen positioned more posteriorly. Furthermore the groove extending anteiorly from the foramen is deeper and more distinct in the skull of P. nodosarius. The I2 from the Kannondo cave site is compa-
rable with those of the living S. scrofa leucomystax, S. scrofa from NT Cave and S. scrofa lydekkeri from Locality 1 of Zhoukou-dian. The I2 coincides with that of S. scrofa leucomystax in morphology and size (Fig. 7). It is also similar to those of S. scrofa from NT Cave and S. scrofa lydekkeri from Locality 1 of Zhoukoudian in morphology, but is considera-
156 M. Fujita and Y. Kawamura April 2001
Fig. 7 Size variation in LLD of I2 and Wa of M3 in the subspecies of the living Sus scrofa, in
comparison with that in the fossils (S. cf. scrofa from the Kannondo cave site and Locality 1
of Ube Kosan Quarry, S. scrofa from NT Cave and S. s. lydekkeri from Locality 1 of
Zhoukoudian)
This figure shows that the size variation of the fossils is accommodated in that of the living
S. scrofa. In the M3 from Locality 1 of Ube Kosan Quarry, Wa is estimated from Wm by the
regression line of Figure 6.
bly smaller. The P4 from the Kannondo cave site is com-
parable with those of the living S. scrofa leucomystax, S. scrofa from NT Cave and S. s. lydekkeri from Locality 1 of Zhoukoudian as well as those of D. ultimus and P. nodosarius. The P4 is very similar to that of the living S. scrofa leucomystax in morphology and size, as far as the preserved part is concerned. The P4 also resembles those of S. scrofa from NT Cave and S. s. lydekkeri from Locality 1 of Zhoukou-dian in general, but it is considerably smaller and its distolingual accessory cusp is better developed. On the other hand, the P4 differs from those of D. ultimus and P. nodosarius in having a relatively slenderer crown and less cuspidate pattern with a high cutting edge. Additionally, the descriptions and figures of P4 of S. liuchengensis, S. australis, S. peii and S. xiaoxhu are obscure in Han et al. (1975) and Han
(1987), and the comparisons with the present P4 are impossible. But it can be said that the P4 of S. xiaoxhu is decidedly smaller than the present P4.
The M3 from Locality 1 of Ube Kosan Quarry is comparable with those of the living S. scrofa leucomystax, S. scrofa from NT Cave and S. s. lydekkeri from Locality 1 of Zhoukoudian as well as those of D. ultimus, P. nodosarius, S. liuchengensis, S. australis, S. peii, S. xiaoxhu and S. bijiashanensis. The M3 is similar to that of the living S. scrofa leucomystax in morphology, but is considerably larger (Figs. 7 and 8). The M3 is coincident with that of S. scrofa from NT Cave in size and shape and with that of S. s. lydekkeri from Locality 1 of Zhoukoudian in shape, but is somewhat smaller than that of S. s. lydekkeri (Fig. 7). On the other hand, the M3 is distinct from
those of D. ultimus and P. nodosarius in having thinner enamel, better developed furrows on the cusps and better developed hypopre-conulid and pentapreconulid. The M3 is also different from S. liuchengensis, S. australis, S.
peii, S. xiaoxhu and S. bijiashanensis in having better developed furrows on the cusps, and better developed hypopreconulid and/or pen-tapreconulid. In addition to these discriminat-
2001年4月 Pleistocene wild boar remains from western Japan 157
Fig. 8 Scatter diagram showing the relationship
between Lhp and Wm in M3 of the fossil
and living wild boars of Sus scrofa or its
allied form
ing characters, M3 of S. xiaozhu is easily distin-
guishable from the present M3 in its much
smaller size.
In conclusion, the present fossil specimens are morphologically similar to the living S. scrofa leucomystax, S. scrofa from NT Cave and S. s. lydekkeri from Locality 1 of Zhoukoudian. Of the specimens, the M3 from Locality 1 of Ube Kosan Quarry approximates that of S. scrofa from NT Cave in size, which are generally larger than the living S. scrofa leucomystax. The remaining specimens from the Kannondo cave site are coincident with the living S. s. leucomystax in size, and therefore smaller than S. scrofa from NT Cave and S. s. lydekkeri from Locality 1 of Zhoukoudian. These size differ-ences are considered to be intraspecific, as Fujita et al. (2000) considered (Fig. 7). On the other hand, all the fossil specimens
described here differ from the Quaternary fossil species listed above, as far as the compa-rable parts are concerned. The comparisons are, however, quite limited owing to the insuffi-ciency of the morphological data of the fossil species, as well as the poor preservation of the
present fossil specimens. The morphological similarity to the living S. scrofa leucomystax, S. scrofa from NT Cave and S. s. lydekkeri sug-
gests that the specimens are taxonomically
near to S. scrofa, but the insufficiency of the comparisons prevents us from identifying them as S. scrofa. Consequently, we assign them to S. cf. scrofa herein. Discussion
The M3 from Locality 1 of Ube Kosan Quarry is the only representative of wild boars in the late Middle Pleistocene of Honshu-Shikoku-Kyushu, when we adopt the chronological framework given by Kawamura (1988, 1991) and Kawamura et al. (1989). This specimen re-ferred to S. cf. scrofa above, resembles the M3 of S. scrofa from the middle Middle Pleistocene of NT Cave in shape and size. In the mammali-an assemblage of NT Cave, S. scrofa is relative-ly abundant (Kawamura et al., 1998), while S. cf. scrofa is rare in the assemblage of Locality 1 ofUbe Kosan Quarry, and no wild boar remains are found in the assemblage of Locality 3 of Ube Kosan Quarry which is also dated as the late Middle Pleistocene (Kawamura, 1988). These facts suggest that the wild boar (S. scrofa or S. cf. scrofa) decreased in number from the middle Middle Pleistocene to the late Middle Pleistocene without any remarkable morphological and size changes. The remains from the Kannondo cave site
are also the only representatives of wild boars certainly dated as the late Late Pleistocene in Honshu-Shikoku-Kyushu. They are also as-signed to S. cf. scrofa, and are coincident with the living S. scrofa leucomystax in morphology and size. Thus they are smaller than the middle and late Middle Pleistocene wild boars. The wild boar in Honshu-Shikoku-Kyushu
probably diminished in size from the late Middle Pleistocene to the late Late Pleistocene. On the other hand, wild boar remains exactly dated as the early Late Pleistocene are un-known. These facts indicate that the wild boaralmost extinguished from the late Middle Pleis-tocene to early Late Pleistocene. In the late Late Pleistocene, however, it appeared in small number, and then drastically increased at the beginning of the Holocene, when we take abundant occurrence of wild boars in archaeo-logical sites and fossil localities of Holocene age into consideration, as already pointed out by Kawamura (1992).
158 M. Fujita and Y. Kawamura April 2001
V. Conclusion
The comparisons with living and Quaterna-ry fossil suid species of East Asia indicate that the Middle Pleistocene remain from Locality 1 of Ube Kosan Quarry (left M3) and the Late Pleistocene remains from the Kannondo cave site (right frontal bone, left I2 and left P4) are similar to Sus scrofa in morphology. But they are allocated only to S. cf. scrofa because of their poor preservation and the insufficiency of the comparisons. Among the remains, the M3 is larger than those of the living S. scrofa leucomystax from Honshu, but is nearly as large as those of S. scrofa from NT Cave. The size of the other three is coincident with that of the living S. s. leucomystax. On the basis of the present study and the
data so far obtained, it is inferred that the wild
boar of S. scrofa or its allied form already
inhabited Honshu-Shikoku-Kyushu in the middle Middle Pleistocene, and decreased in
number toward the Late Pleistocene. The wild
boar of the Middle Pleistocene had a large size
comparable to or somewhat smaller than S. s. lydekkeri of North China. In the early Late
Pleistocene, it is likely that the wild boar was
very rare or almost became extinct in Honshu-Shikoku-Kyushu. In the late Late Pleistocene
localities, it was rarely found, which suggests
the revival of the wild boar in this time. The
wild boar of the late Late Pleistocene was smaller than that of the Middle Pleistocene,
and was nearly as large as that of the Holocene
and living S. s. leucomystax. The wild boar drastically increased at the beginning of the
Holocene, and became a dominant element of
the Holocene terrestrial mammal fauna in Honshu-Shikoku-Kyushu.
Acknowledgments
We are grateful to Messrs T. Haikawa and S. Sugimura of the Akiyoshi-dai Museum of Nat-ural History for assisting one of us (Y. Ka-wamura) with the field survey of 1978 in Ube Kosan Quarry, and for giving him many facilities in the research activities in their museum. The staffs of the quarry (Isa Cement Plant of Ube Kosan Company) including Mr. F.
Shibata permitted him the field survey and
provided useful pieces of information. We also
thank the staffs of the Department of Archaeol-
ogy, Hiroshima University including Mr. T.
Nakagoshi, Prof. T. Kawagoe, Prof. M. Kawase,
Associate Prof. K. Furuse for giving us permis-
sion, facilities and encouragement to study the
specimens from the Kannondo cave site.
Thanks are due to Prof. T. Inada (Okayama University) and Dr. Jin Chang-zhu (Institute of Vertebrate Paleontology and Paleoanthropol-ogy, Academia Sinica=IVPP) who permitted and assisted us to access the comparative spec-imens. The measurements of the collections of the following institutions by us are used to draw Figure 7: American Museum of Natural History (AMNH), British Museum of Natural History (BMNH), IVPP, Department of Anato-my, Osaka City University (OCU), ZoologicalInstitute, Academia Sinica (ZI). We are grateful to Prof. R. H. Tedford, Dr. X. M. Wang and Ms. F. Brady (AMNH); Dr. J. Hooker, Mr. A. Cur-rant and Dr. P. D. Jenkins (BMNH); Dr. M. Abe
(OCU); Prof. Feng Z. J. and Ms. M. Luo (ZI) and many other staffs of the institutions who
permitted and assisted us to access the collec-tions in their care and gave us many facilities. We also thank to many people who helped us to collect the living specimens of S. scrofa leucomystax from Honshu. This study was partly supported by the
Grants-in-Aid from the Ministry of Education, Science, Sports and Culture, Japan (project nos. 11301014 and 09208101).
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160 M. Fujita and Y. Kawamura April 2001
山口県宇部興産採石場第1地 点と広島県帝釈観音堂洞窟遺跡産の
中 ・後期更新世イノシシ化石
藤 田 正 勝*1・ 河 村 善 也*2
(要 旨)
山 口県美祢市 にある宇部興産採石場第1地 点 か ら産 出
した中期更 新世 の イノ シ シ化石1点(下 顎第3大 臼歯)
と,広 島県神石町にあ る帝釈観音堂洞窟遺跡 か ら産 出 し
た後期更 新世 のイノ シシ化石3点(前 頭骨,上 顎第2切
歯,下 顎第4小 臼歯)を 系統分類学 的に記載 し,そ れ らの
形態的特徴を明 らかに した.わ が国では確実 に更新世 の
イノシシ化石 といえ るものは少 な く,こ れ らは更新世 の
本州 ・四国 ・九州 に分布 したイ ノシシの特徴 を知 る上 で
貴重 な材料 とな る.こ れ らの化石 を東 ア ジア産 のイノ シ
シ類の現生種お よび第四紀の化石種 と比較 した結果,現
在 ユー ラ シアに広 く分布 す るSus scrofaに その形態 的
特徴が よ く一致す ることがわか った.し か し,東 ア ジァ
産化石種 の形態 に関す るデータは十分でな く,今 回の化
石標本 も数が少 ない上 に保存 も悪 く,十 分な比較が行 え
なか ったので,今 回は これ らの化石 をS.cf.scrofaと す
るにとどめる.こ れ らの化石 のうち,宇 部興産採石場第
1地 点産 の ものは,現 在 の本州 ・四国 ・九州 に分布す る
S.scrofaの 亜種S.s.leucomystaxの それ よ り大 き く,
ほかの中期更新世 の化石産地 の ものとほぼ同 じ大 きさで
あ った.し か し,帝 釈観音堂洞窟遺跡産の化石 はS.s
leucomystaxと ほぼ同 じ大 きさであ った.今 回 の研究 の
結果 とこれまでに得 られているデータか ら,S.scrofaや
それに近 いイノ シシは中期更新世 中期 にはすで に本州 ・
四国 ・九州 に生息 していて,そ こか ら後期更新世 にかけ
て数 が減少 し,さ らに後期更新世後期 か ら完新世 にかけ
ては逆 に急増 した後,こ の地域 の完新世 の動物相 の主要
な構成要素 とな った と推定 される.
*1大 阪市 立大 学大 学 院理学 研究 科 〒558-8585大 阪 市住 吉区 杉本3-3-138 .E-mail9
*2愛 知 教育 大学地 学教 室 〒448-8542愛 知 県刈 谷市 井 ヶ谷 町広沢1 .