Hominoid Fossils Discovered from Chiang Muan, Northern Thailand

ANTHROPOLOGICAL SCIENCE Vol. 113, 85–93, 2005

Hominoid fossils discovered from Chiang Muan, northern Thailand: the first step towards understanding hominoid evolution in Neogene Southeast Asia YUTAKA KUNIMATSU1*, BENJAVUN RATANASTHIEN2, HIDEO NAKAYA3, HARUO SAEGUSA4, SHINJI NAGAOKA5

1Primate Research Institute, Kyoto University, 41 Kanrin, Inuyama, Aichi, 484-8506 Japan 2Department of Geological Sciences, Faculty of Science, Chiang Mai University, Thailand 3Faculty of Engineering, Kagawa University, Japan 4Himeji Institute of Technology, Japan 5Faculty of Education, Nagasaki University, Japan

Received 5 July 2003; accepted 3 March 2004

Abstract The Thai-Japanese Paleontological Expedition Team (TJPET) has been conducting paleontological and geological fieldwork in Thailand for a number of years. In January 2000, an upper molar (CMu6-1’00) of a large-bodied Miocene hominoid was found by TJPET in a lignite mine in the Chiang Muan basin, northern Thailand. It was the first record of a Miocene hominoid from a Southeast Asian country. Two years later, TJPET found a second hominoid specimen (CMu15-5’01) in the same lignite mine. The second specimen was collected from the Upper Lignite Member, while the first one had come from the Lower Lignite Member. The age of Chiang Muan is estimated to be at around the boundary of the Middle/Late Miocene (ca. 10–12 Ma) based on mammalian fauna and paleomagnetic study. There may be several hundred thousand years temporal difference between the Upper and Lower Lignite Members. Chaimanee et al. (2003) reported more hominoid specimens from the same site, and created a new species, cf. Lufengpithecus chiangmuanensis. The taxonomic status of the Chiang Muan hominoids, however, is still a matter of debate. Nevertheless, the discovery of Miocene hominoids from Chiang Muan has revealed the potential of Thailand for understanding hominoid evolution in Southeast Asia.

Key words: Miocene hominoids, Thailand, Chiang Muan, Lufengpithecus, Southeast Asia

Introduction reported from Lufeng and Yuanmou (for a recent review, see Harrison et al., 2002). In other parts of eastern Eurasia, no Around the end of the Early Miocene, hominoid primates Neogene hominoids have been known except for a single started to expand their distribution from Afro-Arabia into upper molar from Tinau Khola in Nepal (Munthe et al., Eurasia (Heizmann and Begun, 2001). In western Eurasia 1983) and a relatively small and damaged mandible from (Europe to Anatolia), various fossil hominoids have been Wudu in Gansu province, China (Xue and Delson, 1989). reported mainly from the Middle and Late Miocene Although it is in Southeast Asia that extant hominoid pri- (Andrews et al., 1996; Begun, 2002). In eastern Eurasia, the mates such as orang-utans and gibbons survive today, our majority of Miocene hominoid fossils have been discovered knowledge of hominoid evolution in this region is still very from two regions: Siwaliks in India and Pakistan, and Yun- poor (Kunimatsu, 2002a). In order to fill this gap of knowl- nan Province in the southwestern part of the People’s edge, the Thai-Japanese Paleontological Expedition Team Republic of China (Kelley, 2002). For more than a century, (TJPET) has been conducting paleontological and geologi- the Siwaliks have yielded Miocene hominoid fossils, most cal field research at late Cenozoic fossil sites in Thailand of which are now assigned to Sivapithecus, while a few (Saegusa et al., 1999; Kunimatsu et al., 2000b; Nagaoka and specimens belong to Gigantopithecus (Kennedy, 2000). In Suganuma, 2002; Nakaya et al., 2002a; Suganuma et al., Yunnan, since the 1950s when Wu Rukang (old spelling: 2002; Yabe, 2002). Woo Ju-kang) described a new species, “Dryopithecus” keiyuanensis, from a lignite mine at Xiaolongtan, Kaiyuan district (Woo, 1957, 1958), numerous Miocene hominoid Historical sketch remains, which are assigned to Lufengpithecus, have been Fossils from Thailand and adjoining areas have been reported since the early 20th century (for review of early * Corresponding author. e-mail: [email protected] works, see Kobayashi, 1964). Andersson (1916) studied Ter- phone: 81-568-63-0523; fax: 81-568-61-5775 tiary fish remains from northern Thailand. Even during the Published online 13 July 2004 Second World War, paleontological work was done on Per- in J-STAGE (www.jstage.jst.go.jp) DOI: 10.1537/ase.04S013 mian fusulinids (Minato, 1944; Toriyama, 1944).

After the Second World War, von Koenigswald (1959) the Late Oligocene (Ratanasthien, 2002). Recently, Yabe examined proboscidean teeth from the Mae Moh lignite (2002) analyzed plant megafossils collected from Ban Pa mine (Middle Miocene: Benammi et al., 2002) near Lam- Kha by TJPET, and reconstructed the paleoclimate of this pang (Figure 1), and assigned them to a new species, Stegol- area. Ban Pu and Ban Na Klang, several kilometers north of ophodon praelatidens. Later, Ginsburg et al. (1983) studied Ban Pa Kha, also yielded plant megafossils (Kunimatsu et other mammalian remains, as well as proboscidean fossils al., 2000b). from this site. Tassy et al. (1992) treated the Mae Moh pro- In 1982, Ukkakimapan found the first mammalian fossils boscidean remains as Stegolophodon cf. latidens. from Mae Long in the southern part of the Li basin, which In the Li Basin, Endo (1963, 1964) reported plant fossils included an antler of Stephanocemas (a Miocene cervid from the eastern part of the basin (17L50'N, 99L05'E), esti- genus) (Ginsburg and Ukkakimapan, 1983; Ginsburg et al., mated to be of Paleogene age, referring to the Late Eocene 1991). Jaeger et al. (1985) reported two rodent taxa, cf. Diat- flora of Fushin in south Manchuria. Based on pollens and omys sp. and Antemus thailandicus, and suggested a middle spores, Ratanasthien (1984) suggested a wide temporal Middle Miocene age for this site. On the other hand, Mein range from the Senonian or Paleogene to the Oligocene/ and Ginsburg (1985) reported six rodent taxa from the same Early Miocene. The age of initiation of Tertiary-aged basin locality, and proposed a late Early Miocene age (MN3b). development in northern Thailand is now considered to be in Mein et al. (1990) further described rodent fossils from Mae

Figure 1. Geographic locations of Neogene fossil sites in Thailand. Vol. 113, 2005 HOMINOID FOSSILS FROM CHIANG MUAN, NORTHERN THAILAND 87

Long, including two new species, and slightly emended the skeleton by TJPET suggests that the generic assignment of age to be equivalent to MN4. Later, Mein and Ginsburg the Ban Na Sai rhinocerotid remains should be revised (1997) gave a comprehensive report on small and large (Saegusa et al., 1999). mammalian fossils of this site, and placed its age to the In the Pong Basin, Sickenberg (1971) reported Deinothe- beginning of MN4 (late Early Miocene: ca. 18 Ma) with a rium cf. pentapotamiae from Ban Sop Kham. There are two suggestion that the paleoenvironment of Mae Long was a other fossil sites in this basin. One is Huai Siew, 5.5 km tropical rain forest near a shallow lake. north-northeast of the township of Pong (Ginsburg, 1989), In the mid-1980s, one of us (B.R.) collected fossils, and the other is Ban San Klang located in the eastern part of including a proximal part of a humerus belonging to an inde- the Pong Basin (Suteethorn et al., 1990). Both of them are terminate large-bodied mammal (rhinocerotid size) and a considered to be early Middle Miocene with the former complete fish, from a small lignite mine at Ban Na Sai seeming to be slightly older than the latter (Ducrocq et al., (Ginsburg et al., 1991). Subsequently, proboscidean remains 1995) (Figure 2). The mammalian material from Huai Siew were discovered (Ginsburg et al., 1991) and described as a includes a number of tragulids as well as proboscideans, new species, Stegolophodon nasaiensis, that is more primi- perissodactyls like Chalicotherium (Chalicotheriidae) and tive than the Stegolophodon species from Mae Moh (Tassy cf. Gaindatherium (Rhinocerotidae), and an artiodactyl et al., 1992). Rhinocerotid remains from Ban Na Sai have genus Brachyodus (Anthracotheriidae) (Ginsburg, 1989). been assigned to Gaindatherium (Ginsburg and Tassy, 1985; Based on silicified woods from this site, Vozenin-Serra Ducrocq et al., 1994), but a newly found rhinocerotid partial (Vozenin-Serra and Privé-Gill, 1989; Vozenin-Serra et al.,

Figure 2. Ages of Neogene fossil sites in Thailand (after Nakaya et al., 2002a). 88 Y. KUNIMATSU ET AL. ANTHROPOLOGICAL SCIENCE

1989) suggested that mangrove vegetation had preceded the In Mae Soi, there are two subareas called Doi Chang and tropical rain forest there. Interestingly, an isolated lower Kew Hoi Tal. The Doi Chang subarea was named after a hill molar of a small Miocene catarrhine was discovered from called Doi Chang, which means ‘elephant hill’ in Thai. Ban San Klang (Suteethorn et al., 1990); we will discuss this Coincidentally, from a locality of the Doi Chang subarea tooth in more detail below. (TJPET locality DCh1 [GPS data: 18L17'10.5''N, Some other Neogene fossil sites that were previously 98L36'28.7''E], Kunimatsu et al., 2000b), we excavated a known include Had Pu Dai in the Lampang Basin, the Mae skeleton of an amebelodontid proboscidean assigned to Teep lignite mine located ca. 80 km northeast of Lampang, Archaeobelodon (Saegusa et al., 1999; Nakaya et al., and Nong-Hen I (A) near Pitsanulok. Had Pu Dai (or Nah 2002a). In addition, we collected a number of vertebrate, Nai Yod) yielded suids (Conohyus), tragulids (Siamotragu- invertebrate, and plant fossils from twelve localities in the lus), indeterminate rhinocerotids and proboscideans, and Doi Chang subarea (DCh1 to DCh12) and six localities micromammals (Pope and Bernor, 1990; Ducrocq et al., (KHT1 to KHT6) in the Kew Hoi Tal subarea (Kunimatsu et 1995). The age of this site is estimated to be the early Middle al., 2000b, unpublished data). Based on the mammalian Miocene (Ducrocq et al., 1995). From Mae Teep, Buffetaut fauna, the age of Mae Soi is most likely the late Early et al. (1988) reported Stegolophodon sp. Nong-Hen I (A) is Miocene (MN4) (Nakaya et al., 2002a). different from the other fossil sites in that fossils of this site Sop Mae Tham is a village located 45 km southwest of were discovered from drilling cores for exploration wells Lampang. The fossil-yielding area is approximately 2.5 km (Legendre et al., 1988). The Nong-Hen I (A) material con- north of the village. The land is covered with vegetation and sists mainly of bat remains, the majority of which belong to agricultural fields, but there are patches of outcrops around a new species, Mormopterus (Hydromops) nonghenensis two small hills that we called the Eastern and Western Hills. (Legendre et al., 1988). We have extensively collected fossils from more than thirty localities (Kunimatsu et al., 2000b, unpublished data). Thai-Japanese Paleontological Expedition Among these fossils, we identified hipparion teeth, which are the first record of the Hipparionini from Southeast Asia Since 1996, our joint project consisting of Thai and Japa- (Nakaya et al., 2001, 2002a). nese researchers and graduate students of paleontology, We have conducted paleobotanical work, especially in anthropology, and geology has been conducting paleonto- Mae Lai, Ban Pa Kha, Ban Pu, Ban Na Klang, Mae Lamao, logical and geological fieldwork in Thailand. This Thai- and Chiang Muan. Yabe (2002) examined fossil leaves that Japanese Paleontological Expedition Team (TJPET) has TJPET collected at Ban Pa Kha (Late Oligocene) and Mae investigated both new and previously known fossil sites Lai (late Early to middle Middle Miocene), and recon- such as Mae Soi, Sop Mae Tham, Chiang Muan, Mae Oo, structed the paleoenvironment of these two areas by using the Li Basin (Ban Na Sai, Mae Long, Ban Pu, Ban Pa Kha, CLAMP (Climate Leaf Analysis Multivariate Program). His Ban Na Klang), Huai Siew in the Pong Basin, the Mae Moh results indicate a trend of increase in mean annual tempera- lignite mine near Lampang, Mae Lai, Mae Lamao, Tha ture (MAT) with an apparent rise of the cold month mean Chang near Nakhon Ratchasima, and Krabi in the Malay temperature from the Late Oligocene to the early part of the peninsula (Saegusa et al., 1999; Kunimatsu et al., 2000b, Miocene in northern Thailand. In addition, Yabe (2002) sug- unpublished data; Nakaya et al., 2002a, b, c, 2003; Yabe, gested the possibility of paratropical rain forests existing in 2002). this region during the Early to Middle Miocene with a warm

Figure 3. Chiang Muan lignite mine. The mining pit is seen from the south. Vol. 113, 2005 HOMINOID FOSSILS FROM CHIANG MUAN, NORTHERN THAILAND 89

(MAT: 19.2LC) and humid (growing season precipitation: Pickford et al., 2004; personal communications from A. 214.7 cm) climate (contra Ducrocq et al., 1994). Fukuchi). The mammalian fauna and paleomagnetic study In Chiang Muan, we discovered two molars of a large- by Suganuma et al. (2002) suggests that the age of Chiang bodied Miocene hominoid from the lignite mine (Figure 3) Muan is the latest Middle to earliest Late Miocene (ca. 10– operated by the Chiang Muan Mine Company (CMMC). 12 Ma). The first specimen (TJPET No. CMu6-1’00) was discovered during the field season of January 2000 (Kunimatsu et al., Large-Bodied Miocene Hominoids from 2000a; Suvunsavate et al., 2001). In the same year, the dis- Chiang Muan covery was announced at the 16th annual meeting of the Pri- matological Society of Japan. This was the first report of a An isolated upper molar (CMu6-1’00) of a large-bodied Miocene hominoid from a Southeast Asian country (Kuni- Miocene hominoid (Figure 4) was discovered at a lignite matsu, 2002a). Another hominoid specimen (CMu15-5’01) mine in Chiang Muan, northern Thailand, through the field- was discovered from the same lignite mine nearly two years work by TJPET on 22 January 2000 (the discoverer was later (Kunimatsu et al., 2002, 2003). We also collected more Nikorn Wongchai of the CMMC) (Kunimatsu et al., 2000a; than 200 specimens of vertebrate, invertebrate, and plant Suvunsavate et al., 2001). The place of discovery (TJPET remains. In addition, thanks to the efforts of the CMMC locality CMu6) was a slope near the southern end of the min- staff, a number of fossils have been rescued during lignite ing pit. The surface of the slope was covered with remnants excavation, and these fossils are stored in a small exhibition of lignite, and is almost parallel to the general dip of the room at the Chiang Muan mine (Suvunsavate et al., 2001). strata. Although the hominoid upper molar was found on the We have examined these fossils under the care of the surface, it most likely derived from the Lower Lignite Mem- CMMC, and have given them accession numbers with the ber (Nagaoka and Suganuma, 2002). The discovery of this prefix CM (after Chiang Muan). The vertebrate fossils from hominoid fossil was immediately reported to the office of Chiang Muan include three partial skeletons of Tetraloph- the CMMC, according to established procedures for field odon cf. xiaolongtanensis, suids such as Hippopotamodon research at the mine (Suvunsavate et al., 2001). This speci- cf. hyotherioides, Conohyus sindiensis, and Parachleuasto- men is a right M1 or M2 crown of a large-bodied hominoid. choerus sinensis, a tayassuid species Pecarichoerus The size of the crown (MD 11.8 mm P BL 14.0 mm) is sim- sminthos, tragulids (Dorcatherium sp. and Tragulidae ilar to that of extant orangutans (Pongo pygmaeus). The indet.), Chilotherium (Subchilotherium) intermedium a rhi- paracone is broken off. The occlusal surface is heavily worn nocerotid, and bovid, as well as fish, birds, and aquatic rep- (Kunimatsu et al., 2005). tiles like crocodiles and turtles (Kunimatsu et al., 2000b, Nearly two years later, a second specimen (CMu15-5’01) unpublished data; Nakaya et al., 2001, 2002a, b, c, 2003; of a large-bodied hominoid was discovered on 20 December

Figure 4. TJPET hominoid specimens from Chiang Muan. (a) CMu6-1’00, right M1 or M2; (b) CMu15-5’01, right lower molar with the protoconid and metaconid preserved. 90 Y. KUNIMATSU ET AL. ANTHROPOLOGICAL SCIENCE

2001 at the Chiang Muan lignite mine by Bantita Udomkan, Miocene: Dong, 1987; Harrison et al., 2002) or MN78 (late a graduate student of Chiang Mai University, during TJPET Middle Miocene: Qiu and Qiu, 1995). Therefore, these two fieldwork. The place of discovery (TJPET locality CMu15) sites are also close to each other in geological age. Nearly is situated in the Upper Lignite Member, approximately half a century ago, a famous Chinese anthropologist, Wu 60 m higher than the Lower Lignite Member (Nagaoka and Rukang, described a new species of large-bodied hominoid Suganuma, 2002). This specimen is a fragment of a right “Dryopithecus” keiyuanensis based on several lower cheek lower molar preserving the protoconid and metaconid (Fig- teeth from Xiaolongtan (Woo, 1957, 1958). Although he ure 4). The cusps are unworn. The two cusps are relatively used the generic name Dryopithecus according to the taxon- low, rounded, and voluminous, and connected with each omy accepted in those days, he correctly pointed out the other by double mesial transverse crests. The mesial fovea is similarities of the Xiaolongtan material to the Siwalik restricted. The preserved part of the talonid basin is coarsely Miocene hominoids (Dryopithecus punjabicus in Woo, crenulated. 1957), which are now treated as Sivapithecus. Zhang (1987) Apart from the hominoid fossils discovered through added to the Xiaolongtan hominoid material a palate with TJPET field research, Chaimanee et al. (2003) reported right C–M2 and left I2–M3, and a left lower tooth row with additional hominoid specimens from the same lignite mine M1–M3. He suggested similarities of the Xiaolongtan mate- in Chiang Muan. They assigned these hominoid specimens rial to “Ramapithecus” lufengensis (now Lufengpithecus to a new species, cf. Lufengpithecus chiangmuanensis. lufengensis) from Lufeng, a Late Miocene hominoid site With the aid of peripheral Quantitative Computer Tomog- west of Kunming, Yunnan Province. More recently, other raphy (pQCT) and a 3D reconstruction computer program researchers (Zheng and Zhang, 1997; Harrison et al., 2002; (INTAGE), relative enamel thickness (Martin, 1985) is esti- Kelley, 2002) have included the Xiaolongtan hominoid mated to be 22.6 for CMu15-5’01, which means that this material in Lufengpithecus (here we tentatively call it ?L. specimen has thick molar enamel (Kunimatsu et al., 2005). keiyuanensis). The relationship of ?L. keiyuanensis to the This value is similar to the average (22.4) of extant Homo other Lufengpithecus materials from Lufeng and Yuanmou is sapiens, and slightly exceeds the range of intraspecific vari- still debated, but it is apparent that ?L. keiyuanensis is mor- ation (11.3–20.5) in extant orang-utans (Martin, 1985). phologically, geographically, and temporally similar to the Chaimanee et al. (2003) provided slightly smaller values for Chiang Muan hominoid material, and is important in deter- two other hominoid molars from Chiang Muan (17.23 and mining the taxonomic status of the Chiang Muan hominoids. 17.80), but these values are also included within the range of Unfortunately, the Xiaolongtan hominoid material was not intraspecific variation of extant H. sapiens (13.8–32.3) mentioned in the description of cf. L. chiangmuanensis by (Martin, 1985). The difference of relative enamel thickness Chaimanee et al. (2003), so that it is not yet clear whether between CMu15-5’01 and the two specimens in Chaimanee these two materials are really two different species or not. et al. (2003) is not so great, and can be interpreted as The above-mentioned situation suggests that cf. L. chiang- intraspecific variation. Proconsul nyanzae (22.3–27.6), muanensis could be a junior synonym of ?L. keiyuanensis Afropithecus turkanensis (19.9–22.9), Lufengpithecus lufen- (Kunimatsu et al., 2005; Pickford et al., 2004). gensis (24.1–24.6), and Graecopithecus freybergi (28.3) show similar or slightly larger values compared to CMu15- A Small ‘Hominoid’ Molar from Ban San Klang 5’01 (Beynon et al., 1998; Schwartz et al., 2003; Smith et al., 2003). Before the first announcement (Kunimatsu et al., 2000a) CMu15-5’01 and all hominoid specimens described by of a large-bodied hominoid fossil (CMu6-1’00), Suteethorn Chaimanee et al. (2003) derive from the Upper Lignite et al. (1990) had reported an isolated lower molar of a small Member (Nagaoka and Suganuma, 2002). They are similar catarrhine from an early Middle Miocene site at Ban San in size and share general morphological traits such as low Klang in the Pong Basin, northern Thailand. They assigned and voluminous cusps, reduced buccal cingulum, and double it to a new species of small-bodied hominoid, Dendropithe- mesial transverse crests (at least in CMu15-5’01 and cus orientalis. The type species of the genus is Dendropith- TF6179, a left dp4). Therefore, they should be assigned to ecus macinnesi from the Early Miocene of East Africa, the same species. On the other hand, the first hominoid spec- thousands of kilometers away from Southeast Asia, and it is imen (CMu6-1’00) was discovered from the Lower Lignite the only species of the genus that had been known before the Member (Nagaoka and Suganuma, 2002), which is ca. 60 m Ban San Klang lower molar was described. Dendropithecus below the Upper Lignite Member, so that CMu6-1’00 is and some other small Miocene catarrhines in East Africa probably several hundred thousand years older than the have been called small-bodied Miocene apes, but their hom- other hominoid specimens from Chiang Muan. However, inoid status has been doubted (Harrison, 1988). It is more since CMu6-1’00 is similar in size and morphology to the likely that they are a group of primitive catarrhines that hominoid specimens from the Upper Lignite Member, it diverged before the split of extant hominoids and cercopith- seems appropriate to provisionally treat them as the same ecoids (Harrison, 2002). In addition, it is often difficult to species at present. However, the taxonomy of the Chiang precisely identify a single isolated molar of hominoid or Muan hominoid material is still a matter of debate. hominoid-like primate. The description by Suteethorn et al. Among the Miocene hominoid sites in eastern Eurasia, (1990) does not give clear characters that uniquely connect the Xiaolongtan lignite mine in Kaiyuan is geographically the Ban San Klang molar to the East African D. macinnesi. closest to Chiang Muan (ca. 650 km northeast). The age of In their revision of the Early Miocene primate fossils from Xiaolongtan (Kaiyuan) is estimated as MN9 (early Late Sihong, Jiangsu Province of the People’s Republic of China, Vol. 113, 2005 HOMINOID FOSSILS FROM CHIANG MUAN, NORTHERN THAILAND 91

Harrison and Gu (1999) interpreted the Ban San Klang Acknowledgments molar to be closely related to pliopithecids from Sihong (Dionysopithecus shuangouensis). With the paucity of the Our sincere thanks go to the Chiang Muan Mine Com- pany for permitting us to conduct field survey and to exam- Ban San Klang primate material, it appears better to treat it as Dionysopithecus orientalis for the time being (Harrison ine their fossil collection. The staff of the CMMC, especially and Gu, 1999). Nikorn Wongchai and Arong Sritulakarn, gave kind support to our study. We are grateful to the staff and students of the Department of the Geological Sciences of Chiang Mai Uni- Discussion versity, especially Thanuchai Silaratana, Yupa Thasod, Wic- kanet Songtham, and Rattanaporn Hanta, for their assistance Little is known about Neogene hominoid evolution in the during the field survey. Yang Changman of the Raffles Indochina peninsula and Southeast Asian archipelago. How- Museum of Biodiversity, National University of Singapore, ever, recent TJPET paleontological fieldwork in Chiang Boeadi of the Bogor Zoological Museum, Indonesia, Samir Muan (Kunimatsu et al., 2000a, b, 2002, 2003, 2005; Sen Gupta of the Geological Survey of India, Lu Qingwu Nagaoka and Suganuma, 2002; Nakaya et al., 2002a, b, c; and Pan Yuerong of the Institute of Vertebrate Paleontology Suganuma et al., 2002) revealed that hominoids had already and Paleoanthropology, China allowed one of the authors inhabited Thailand by the latest Middle Miocene. Chiang (Y.K.) to examine the extant and fossil primate specimens Muan is the first Miocene hominoid site that lies south of the under their care. We also appreciate Nobuo Shigehara and Tropic of Cancer in eastern Eurasia (Kunimatsu, 2002a; Osamu Takenaka of the Primate Research Institute, Kyoto Kunimatsu et al., 2005). This also means that Chiang Muan University for their support to our overseas research in Thai- is currently the southernmost Miocene hominoid site of the land. The Thai-Japanese Paleontological Expedition was Eurasian continent (Kunimatsu, 2002b). Although the hom- supported financially by the Grant-in-Aid for COE Research inoid material collected from the Upper Lignite Member (#10CE2005) from the Ministry of Education, Culture, was assigned to a new species, cf. Lufengpithecus chiang- Sports, Science and Technology of Japan. muanensis (Chaimanee et al., 2003), the taxonomic status of the Chiang Muan hominoid material has yet to be carefully investigated (Kunimatsu et al., 2005). In addition to work at Chiang Muan, TJPET is conducting paleontological field References work and analyses of museum specimens at various places Andersson E. (1916) Beschreibung einiger Fischreste aus Mada- in Thailand. For example, we have collected vertebrate and gascar und Siam. Bulletin of the Geological Institute, Upp- plant fossils from sandpits in Tha Chang near Nakhon Rat- sala, 13: 227–232 (cited in Kobayashi, 1964). chasima (or Khorat). We have also analyzed the vertebrate Andrews P., Harrison T., Delson E., Bernor R.L., and Martin L. fossils that were previously discovered from Tha Chang and (1996) Distribution and biochronology of European and Southwest Asian Miocene catarrhines. In: Bernor R.L., Fahl- stored in the museum of Rajabhat Institute Nakhon Rat- busch V., and Mittmann H.-W. (eds.), The Evolution of West- chasima, and in some other public and private collections. ern Eurasian Neogene Mammal Faunas. Columbia University We have recognized in the Tha Chang material multiple Press, New York, pp. 168–207. mammalian assemblages of the Middle Miocene, latest Begun D.R. (2002) European hominoids. In: Hartwig W.C. (ed.), Miocene to Early Pliocene, and Early Pleistocene (Nakaya et The Primate Fossil Record. 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