PALEVO 1631-0683 Elsevier S1631-0683(03)00157-X 10.1016/j.crpv.2003.09.029 Research article Human Palaeontology and Prehistory Age and taxonomic status of the Chiang Muan (Thailand) hominoids Pickford Martin pickford@mnhn.fr a Nakaya Hideo nakaya@eng.kagawa-u.ac.jp b Kunimatsu Yutaka kunimats@pri.kyoto-u.ac.jp c Saegusa Haruo saegusa@nat-museum.sanda.hyogo.jp d Fukuchi Akira dns15603@cc.okayama-u.ac.jp e Ratanasthien Benjavun benjavun@geol.science.cmu.ac.th f Département ‘Histoire de la Terre’, UMR 5143 du CNRS, 8, rue Buffon, 75005, Paris, France & Collège de France, 11, place Marcellin-Berthelot, 75005, Paris, France Department of Earth and Environmental Sciences, Kagawa University, Takamatsu, 761-0396, Japan Primate Research Institute, Kyoto University, Kanrin, Inuyama, Aichi, 484-8506, Japan Haruo Saegusa, Institute of Natural and Environmental Sciences, Himeji Institute of Technology, Sanda, 669-1546, Japan Akira Fukuchi, Department of Earth Sciences, Okayama University, Okayama, 700-8530, Japan Benjavun Ratanasthien, Department of Geological Sciences, Chiang Mai University, Chiang Mai, 50200, Thailand 3 1 S1631-0683(00)X0016-4 65 75 © 2003 Académie des sciences. Published by Elsevier B.V. All rights reserved. 2003 Académie des sciences Full (PDF)

The age of the recently created hominoid species from Thailand, cf. Lufengpithecus chiangmuanensis Chaimanee et al., 2003 [2], was originally estimated to be ca 13–13.5 Ma, based on faunal and palaeomagnetic correlations. Previous studies of the Chiang Muan fauna (including hominoids) and palaeomagnetism suggest that the deposits are appreciably younger than this, being closer in age to Xiaolongtan (China) (ca 12–11 Ma) rather than to the Chinji fauna of Pakistan. The similarities between hominoids from the Thai and Chinese localities are clear, and we conclude that cf. L. chiangmuanensis should be treated as a synonym of ?Lufengpithecus keiyuanensis Wu, 1957.

L'âge et taxonomie des hominoïdes de Chiang Muan (Thaïlande). L’âge de la nouvelle espèce d’hominoïdes thaïlandais, cf. Lufengpithecus chiangmuanensis Chaimanee et al., 2003 [2], a été estimé à environ 13–13.5 Ma, à partir des corrélations fauniques et paléomagnétiques. Des études antérieures de la faune de Chiang Muan (incluant les hominoïdes) et du paléomagnétisme ont suggéré que les dépôts sont plus jeunes, d’un âge proche de celui du gisement chinois de Xiaolongtan (ca 12–11 Ma), plutôt que de celui des faunes de Chinji au Pakistan. Les similarités entre les hominoïdes des localités chinoises et thaïlandaises sont évidentes et nous en concluons que cf. L. chiangmuanensis devrait être considéré comme un synonyme de ?Lufengpithecus keiyuanensis Wu, 1957.

Thailand, Miocene, Hominoidea, Biochronology, Palaeomagnetism, Taxonomy Thaïlande, Miocène, Hominoidea, Biochronologie, Paléomagnétisme, Taxonomie presented Presented by Yves Coppens Version française abrégée Introduction

Chaimanee et al. [2] ont comparé les faunes de Chiang Muan à celles des Siwaliks du Pakistan et ont conclu que les dépôts étaient contemporains de ceux de la formation de Chinji [1]. Ils ont identifié un des suidés de Chiang Muan comme Hyotherium pilgrimi, dont l’âge se situe entre 14 et 11,3 Ma. Toutefois, cette espèce étant rare dans les Siwaliks [14], son intérêt biostratigraphique s’avère faible. Cette espèce n’est pas représentée dans les très importantes collections réalisées à Chiang Muan par la Japan–Thailand Palaeontology Expedition, suggérant que l’identification n’est peut-être pas exacte. Les autres mammifères signalés par Chaimanee et al. [2] consistent en un stégolophodonte, et les ruminants Eotragus, Dorcatherium, et Siamotragulus. Sans identification au niveau spécifique, ces déterminations ne fournissent pas d’indications sur l’âge des dépôts.

 Biochronologie

Nous avons comparé les mammifères de Chiang Muan (Table 1) avec la faune des lignites de Xiaolongtan (District de Kaiyuan, Chine) [3, 4], un site qui est géographiquement beaucoup plus proche de celui de Chiang Muan que le dernier ne l’est des Siwaliks. Le proboscidien de Chiang Muan est rapporté à Tetralophodon cf. xiaolongtanensis [13] (Fig. 1). Les suidés de Chiang Muan comprennent quatre taxons, deux d’entre eux sont connus à Xiaolongtan : Parachleuastochoerus sinensis (dont la localité-type est Xiaolongtan) (Figs. 2 et 3) et Hippopotamodon cf. hyotherioides, plus petit que H. sivalensis [7, 9, 14]) (Fig. 4). Les deux autres sont signalés dans le Miocène moyen terminal des dépôts des Siwaliks au Pakistan : Conohyus sindiensis (Fig. 2) et le tayassuidé Pecarichoerus sminthos [7]. L’âge Miocène moyen de Xiaolongtan a été estimé sur la présence d’un Listriodon [3], mais le spécimen considéré s’avère être une I2 supérieure d’Hippopotamodon cf. hyotherioides [9]. Pickford & Liu [14] ont avancé un âge de 10 Ma environ pour le gisement de Xiaolongtan, mais ce dernier pourrait être légèrement plus ancien, 11 à 12 Ma.

 Stratigraphie paléomagnétique

La stratigraphie paléomagnétique de la séquence de Chiang Muan réalisée par Suganuma et al. [16] (Fig. 5) est identique à celle proposée ultérieurement par Chaimanee et al., [2], mais elle a été interprétée comme représentant les chrones C5A à C5, plutôt que le chrone plus ancien C5ABn. Chaimanee et al. [2] ont proposé quatre corrélations avec la zone supérieure de polarité normale (N2), mais ils ont préféré la plus ancienne (C5ABn = ca 13.5 Ma). Si les corrélations de Suganuma et al. [16] sont correctes, alors le Lower Lignite Member appartiendrait au Miocène moyen terminal (environ 12 Ma) et le Upper Lignite Member au Miocène moyen de base (environ 10 Ma), ce qui est en accord avec nos données biochronologiques. À partir des données combinées du paléomagnétisme et de la faune, nous concluons que les hominoïdes de Chiang Muan ont un âge de 11 à 12 Ma.

 L’hominoïde de Chiang Muan

Dans ses travaux antérieurs, Kunimatsu et al. [7–9] ont signalé des hominoïdes dans les deux horizons de lignite du gisement de Chiang Muan. Nous les avons comparés [2, 10–12] à ceux de Xiaolongtan [18–21].

Lorsque Woo Rukang [18] a décrit pour la première fois, en 1957, le matériel de Xiaolongtan (connu à l’époque sous le nom de Kaiyuan), celui de Lufeng n’était pas encore connu et il avait raison de conclure que ce dernier était plus proche de celui des Siwaliks que de l’européen (tous les deux, à l’époque, avaient été rapportés au genre Dryopithecus). Plus tard, lorsque Woo et d’autres collègues chinois [21] étudièrent le matériel de Lufeng, ils y reconnurent deux genres, Sivapithecus et Ramapithecus. Puis, en 1987, Wu [20] attribua l’ensemble du matériel à un nouveau genre, Lufengpithecus. La même année, Zhang [21] rapporta les pièces de Kaiyuan et de Lufeng à Ramapithecus (et Sivapithecus).

La majorité des caractères utilisés par Wu [20] pour distinguer Lufengpithecus de Sivapithecus sont présents dans la face et le palais. Il ne signala que deux différences dentaires : des cuspides plus hautes et des replis d’émail plus nombreux sur la surface occlusale de Lufengpithecus. La hauteur des cuspides est difficile à évaluer précisément, en particulier sur des dents usées. Les ridulations d’émail peuvent être très vite gommées par l’usure mais, sur les photos publiées des dents de Chiang Muan [2], on voit très nettement l’émail crénelé sur quelques molaires. Une autre différence possible entre les deux genres signalée par Ward [17] est la localisation plus centrale des cuspides sur les molaires de Sivapithecus et plus périphérique chez Lufengpithecus et les orangs-outans. Pour ce caractère, Lufengpithecus semble intermédiaire entre Sivapithecus et l’orang-outan. Bien qu’elle soit difficile à estimer, la morphologie dentaire des hominoïdes de Chiang Muan et de Xiaolongtan semble intermédiaire entre Sivapithecus et Lufengpithecus. Zheng et Zhang [22] signalent que les cuspides sont disposées plus centralement chez les hominoïdes de Yuanmou que sur ceux de Lufeng. La région interorbitaire est étroite chez Sivapithecus, mais le crâne juvénile de Yuanmou montre que cette région était large comme chez Lufengpithecus lufengensis. Les hominoïdes de Chiang Muan conservent un cingulum faible aux molaires, mais pas Sivapithecus, et à la différence des grands singes de Lufeng, ils présentent un cingulum mésio-lingual aux molaires supérieures.

La taxonomie et la phylogénie des hominoïdes miocènes de Thaïlande et de Chine sont donc problématiques, et le nom générique qui devrait être donné aux fossiles de Chiang Muan reste incertain. Les caractères discriminants de cf. Lufengpithecus chiangmuanensis [2] sont la morphologie de l’incisive centrale inférieure et de la canine inférieure ; mais ces régions ne sont pas conservées sur le matériel de Xiaolongtan. La question de l’espèce est plus facile à résoudre, comme nous n’avons pas observé de différence morphologique ou métrique significative dans les régions anatomiques communes aux fossiles des deux sites (en particulier les molaires et les prémolaires (Tableau 2). Nous en concluons que ?Lufengpithecus chiangmuanensis Chaimanee et al., 2003 [2] devrait être considéré comme un synonyme de ?Lufengpithecus keiyuanensis Woo, 1957 [18].

 Conclusions

À partir des corrélations faunique et paléomagnétique, la séquence fossilifère de Chiang Muan (Thaïlande) est comprise entre la fin du Miocène moyen et la base du Miocène supérieur (12–10 Ma environ). Elle apparaît presque contemporaine de celle des dépôts chinois de Xiaolongtan (Kaiyuan District), qui est la localité type de Dryopithecus keiyuanensis Woo, 1957 [18] récemment ré-attribué au genre Lufengpithecus [6, 22]. La similitude morphologique et métrique entre les dents de ?L. keiyuanensis et celles de cf. Lufengpithecus chiangmuanensis sont évidentes et la dernière devrait être considérée comme synonyme de la première. Pour quelques caractères, les dents attribuées à ?L. keiyuanensis sont intermédiaires entre celles de Sivapithecus des Siwaliks du Pakistan et de l’Inde et celles de Lufengpithecus lufengensis. L’attribution générique des hominoïdes de Chiang Muan et de Xiaolongtan ne pourra être déterminée avec certitude que lorsque de meilleurs échantillons seront connus dans les gisements thaïlandais et chinois. Toutefois, ces découvertes fournissent un lien potentiellement important entre les Sivapithecinae du sous-continent indien et les hominoïdes de grande taille du Miocène terminal de Thaïlande et de Chine.

 Introduction

Chaimanee et al. [2] compared mammalian fossils from Chiang Muan lignite mine (Thailand) with the Siwalik faunas of Pakistan, and concluded that the Thai assemblage is similar to that of the Chinji Formation [1] principally on the basis of the proboscideans, suids and ruminants. A combination of the faunal, palaeomagnetic and tectonic data prompted the authors to propose a wider range of ages for the hominoids (13.5–10 Ma) spanning the Middle Miocene/Late Miocene boundary. However they considered that the best fit for their palaeomagnetic data was chron C5ABn for the upper normal zone (13.3–13.5 Ma) from which the hominoid fossils were collected. This would place them squarely in the Middle Miocene. However, previous results of the Japan–Thailand team suggest that the deposits are somewhat younger, the lower lignite being about 12 Ma and the upper lignite about 11 Ma. The aim of this paper is to re-examine the question of the age and taxonomic status of the Chiang Muan hominoids.

 Biostratigraphy and biochronology

Chaimanee et al. [2] compared the Chiang Muan fauna with that from the Siwaliks of Pakistan and concluded that the deposits were equivalent in age to the Chinji Formation [1]. In particular they identified one of the Chiang Muan suids as Hyotherium pilgrimi, which is said to range from 14–11.3 Ma. However, because this species is rare in the Siwaliks (only six specimens known from two localities, Chinji, Perim Island [14]), its value for biostratigraphy is minimal. The species appears not to be present in more extensive fossil samples collected at Chiang Muan by the Japan–Thailand Palaeontology Expedition, suggesting that the identification may be suspect. Other mammals listed by Chaimanee et al. [2] consisted of a stegolophodont, and the ruminants Eotragus, Dorcatherium, and Siamotragulus. Without identifications at the species level, these determinations do not yield any valuable indications of the age of the deposits.

We have compared mammals from Chiang Muan (Table 1) with fauna from the lignites of Xiaolongtan (Kaiyuan District, China) [3] and [4] a site that is geographically considerably closer to Chiang Muan (650 km) than the latter is to the Siwaliks (ca 3000 km). The proboscidean from Chiang Muan is Tetralophodon cf. xiaolongtanensis [13] (Fig. 1 ). The suoids from Chiang Muan comprise four taxa, two of which occur at Xiaolongtan (Parachleuastochoerus sinensis (type locality, Xiaolongtan) (Fig. 2 and Fig. 3 ) and Hippopotamodon cf. hyotherioides (smaller than H. sivalensis) [7], [9] and [14] (Fig. 4 ), and two of which are known from latest Middle Miocene Siwalik deposits in Pakistan (Conohyus sindiensis (Fig. 2) and the tayassuid Pecarichoerus sminthos [7], the latter also known from Xiaodian (Hubei Province) China, but under the name Macaca youngi [5]). A record of Listriodon from Xiaolongtan [3] which was taken as providing evidence of a Middle Miocene age, is incorrect, being based on an upper second incisor of Hippopotamodon cf. hyotherioides [9]. Pickford and Liu [14] estimated an age of ca 10 Ma for Xiaolongtan, but it could be slightly older, perhaps between 12 and 11 Ma.

In Chinese mammalian zone terminology, the Chiang Muan sediments correlate closest with the Uppermost Tunggurian and Basal Baodean, appreciably older than Lufeng, the type locality of Lufengpithecus lufengensis [15] and [20]. In terms of the Siwalik succession the Thai and Chinese deposits correlate most closely to late Chinji and basal Nagri levels [7] and they equate with the top of Mammalian Zone MN 8 and the base of MN 9 of the European sequence [1] and [8] (Fig. 5 ). Neither Xiaolongtan nor Chiang Muan have yielded the equid Hipparion, but, being lignite deposits, this absence could be due to ecological factors rather than to the deposits being older than the Hipparion datum. However, the presence of Conohyus sindiensis at Chiang Muan tilts the balance towards a latest Middle Miocene age, perhaps between 12 and 11 Ma, and part of the succession could indeed be pre-Hipparion in age. In view of the faunal similarity and geographic proximity of Chiang Muan to Xiaolongtan, we conclude that the two sites are of similar age.

 Palaeomagnetic stratigraphy

Palaeomagnetic stratigraphy of the Chiang Muan sequence by Suganuma et al. [16] (Fig. 5) yielded the same normal–reversed–normal succession subsequently reported by Chaimanee et al. [2], but which was interpreted to represent chrons C5A to C5 rather than the older chron C5ABn. Out of four correlations of the upper normal polarity zone (N2) proposed by Chaimanee et al. [2], they preferred the earliest one (C5ABn = ca 13.5 Ma). This is unlikely on the grounds that, in the Siwaliks of Pakistan, this polarity zone falls within the Kamlial faunal zone (Fig. 5), not only at odds with the faunal correlations of Chaimanee et al., but also with those of the Japan–Thailand team, both of which noted similarities to Chinji and basal Nagri faunas. If the correlations of Suganuma et al. [16] are correct, then the Lower Lignite Member would be terminal Middle Miocene (ca 12 Ma) and the Upper Lignite Member basal Late Miocene (ca 10 Ma), which accords with our biochronological estimate and would indicate that the Chiang Muan succession spans the Middle Miocene/Late Miocene boundary.

Considering the combined faunal and palaeomagnetic data, we conclude that the Chiang Muan hominoids are unlikely to be as old as 13.3–13.5 Ma, the preferred age of Chaimanee et al. [2], but are more likely to be ca 12–11 Ma (uppermost Middle Miocene to basal Late Miocene).

 The Chiang Muan hominoid

In previous reports, Kunimatsu et al. [10], [11] and [12] recorded hominoids from both of the Chiang Muan lignite horizons. We have compared the Chiang Muan hominoid fossils [2], [10], [11] and [12] with those from Xiaolongtan [18], [19], [20] and [21].

When Woo Rukang [18] first described the Xiaolongtan (at the time referred to as Kaiyuan) material in 1957, the Lufeng material was not yet known, and he was right in saying that the Kaiyuan fossils were more similar to the Siwalik hominoids than to European ones, both of which were at that time attributed to the genus Dryopithecus. The Siwalik specimens were subsequently re-attributed to Sivapithecus. Later, when Woo and other Chinese researchers [21] studied the Lufeng material, they first considered that it included Sivapithecus and Ramapithecus according to the taxonomic fashion of those days. It is in his 1987 article that Wu [20] formally gave a new generic name Lufengpithecus to the Lufeng hominoid. In 1987, Zhang [21] referred to the Kaiyuan and Lufeng materials as Ramapithecus (and Sivapithecus). However, in his conclusion, he said that “the Kaiyuan Ramapithecus is similar to Ramapithecus wickeri from Kenya, and it shares more features with the Lufeng Ramapithecus that is geographically closer (ca. 180 km). Considering the geological age, geography, and morphological features, the author concludes that the Kaiyuan Ramapithecus may be the ancestor of the Lufeng Ramapithecus” [21 (p.85, original text in Chinese)].

The majority of features that Wu [20] used to distinguish Lufengpithecus from Sivapithecus occur in the face and palate. He pointed out only two dental differences: higher cusps and more wrinkles on the occlusal surface in Lufengpithecus. Cusp height is difficult to assess precisely, especially in worn teeth. Wrinkles on the occlusal surface can be obscured quickly by wear, but the photos of the Chiang Muan hominoid teeth published by Chaimanee et al. [2] show considerably crenulated enamel on some molars. Another possible difference between the genera pointed out by Ward [17] is the more centrally located molar cusps in Sivapithecus versus more peripherally located cusps in Lufengpithecus and orangutans. In this feature Lufengpithecus seems intermediate between Sivapithecus and orangutans, and there may be intrataxon variations. Even though it is difficult to assess, it appears that the condition in the Chiang Muan and Xiaolongtan dental material is intermediate between Sivapithecus on the one hand, and Lufengpithecus on the other. Zheng and Zhang [22] say that the cusps are more centrally located in hominoids from Yuanmou than they are in the Lufeng ones, but the juvenile skull from Yuanmou suggests a broad interorbital region, as in Lufengpithecus lufengensis. The Chiang Muan hominoids still retain weak molar cingula, whereas Sivapithecus does not. According to Zheng and Zhang [22], the Yuanmou hominoids differ from the Lufeng ones in retaining the mesio-lingual cingulum on the upper molars.

The taxonomy and phylogeny of the Thai and Chinese Miocene hominoids are problematic, and what generic name should be attributed to the Chiang Muan material is uncertain. The distinguishing characters of cf. Lufengpithecus chiangmuanensis are the morphology of the lower central incisor and lower canine, but these parts are not preserved in the Xiaolongtan material. The question of species is easier to resolve, as we have observed no significant morphological or metric differences in the parts common to the two sites (molars, premolars) (Table 2) – they are extremely similar to each other. On this basis and considering their similar age and geographic proximity, we conclude that ?Lufengpithecus chiangmuanensis Chaimanee et al., 2003 [2] should be treated as a junior synonym of ?Lufengpithecus keiyuanensis Woo, 1957 [18].

 Conclusions

On the basis of faunal correlation and interpretation of palaeomagnetic stratigraphy, the Chiang Muan (Thailand) fossiliferous sequence spans the end of the Middle Miocene and the base of the Late Miocene epochs (ca 12–10 Ma). It is close in age to the Chinese deposit at Xiaolongtan (Kaiyuan District), which is the type locality of Dryopithecus keiyuanensis Woo, 1957 [18] recently re-assigned to the genus Lufengpithecus [6] and [22]. The morphological and metric similarity between the teeth of ?L. keiyuanensis and those of cf. Lufengpithecus chiangmuanensis are manifest, and it is concluded that the latter should be treated as a synonym of the former. In some respects, the teeth of ?L. keiyuanensis are intermediate between those of Sivapithecus from the Siwaliks of Pakistan and India, and those of Lufengpithecus lufengensis. The question of the generic status of the Chiang Muan and Xiaolongtan hominoids can only be satisfactorily determined when better samples of the Thai and Chinese species become available. However, these discoveries provide a potentially important link between the sivapithecines of the Indian Subcontinent and the Late Miocene large hominoids of Thailand and China.

 Acknowledgements

We acknowledge a Grant-in-Aid from the Ministry of Education (Culture, Sports, Science and Technology) of Japan, and the help of Mr Nikon Wongchai and Mr Arong Sritulakarn of the Chiang Muan Mine (research permission and their kind support), Dr Shinji Nagaoka of Nagasaki University (geological research) and Mr Yusuke Suganuma of the University of Tokyo (palaeomagnetic research). Dr Brigitte Senut kindly translated the abridged French version.

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1–4, CMu 2–1, Tetralophodon cf. xiaolongtanensis; 1–2, left M3/s; 3, broken left m/3; 4, right m/3; 5a–6b, CMu 10 1′01, Hippopotamodon cf. hyotherioides, right mandible, occlusal and buccal views (scale intervals, 1 cm).

Fig. 1. 1–4, CMu 2–1, Tetralophodon cf. xiaolongtanensis ; 1–2, M3 supérieures gauches ; 3, M3 inférieure gauche cassée ; 4, M3 inférieure droite ; 5a–6b, CMu 10 1′01, mandibule droite d’Hippopotamodon cf. hyotherioides, vues occlusale et buccale (échelles : 1 cm).

1–6, CM 201, Parachleuastochoerus sinensis from Chiang Muan, Thailand, 1–3, left mandibular cheek teeth, labial, stereo occlusal and lingual views of tooth row; 4–6, lingual views of premolars; 7–9, CM 205, Hippopotamodon cf. hyotherioides, right m/3, buccal, stereo occlusal and lingual views; 10–11, CM 208, Parachleuastochoerus sinensis, upper canine, buccal and lingual views; 12–14, CM 202, Conohyus sindiensis right m/3, lingual, stereo occlusal and buccal views.

Fig. 2. 1–6, CM 201, Parachleuastochoerus sinensis de Chiang Muan, Thaïlande, 1–3, dents jugales mandibulaires gauches, vues labiale, occlusale stéréoscopique et linguale de la rangée dentaire ; 4–6, vues linguales des prémolaires ; 7–9, CM 205, Hippopotamodon cf. hyotherioides, M3 inférieure droite, vues buccale, occlusale stéréoscopique et linguale ; 10–11, CM 208, Parachleuastochoerus sinensis, canine supérieure ; vues buccale et linguale; 12–14, CM 202, Conohyus sindiensis, M3 inférieure droite, vues linguale, occlusale stéréoscopique et buccale.

Univariate metric comparisons of Chiang Muan (Thailand) Parachleuastochoerus sinensis with the type material from Xiaolongtan, China.

Fig. 3. Comparaisons métriques univariées de Parachleuastochoerus sinensis Chiang Muan (Thailand) avec le matériel type de Xiaolongtan (Chine).

Bivariate metric comparison of Chiang Muan (Thailand) Suinae with Hippopotamodon species from the Siwaliks (Pakistan) and Lufeng (China).

Fig. 4. Comparaisons métriques bivariées du Suinae de Chiang Muan (Thaïlande) avec l’espèce d’Hippopotamodon des Siwaliks (Pakistan) et Lufeng (Chine).

Biochronology and palaeomagnetic stratigraphy of Chiang Muan (Thailand) and the Siwaliks (Pakistan) and correlation to Xiaolongtan (Kaiyuan District, China).

Fig. 5. Biochronologie et stratigraphie paléomagnétique des gisements de Chiang Muan (Thaïlande) et des Siwaliks (Pakistan) et corrélation avec le gisement de Xiaolongtan (Chine).

Faunal list, Chiang Muan, Thailand.

Liste faunique du gisement de Chiang Muan, en Thaïlande

OSTEICHTHYES AVES REPTILIA Testudines Squamata Serpentes Crocodylia MAMMALIA Primates Hominoidea ?Lufengpithecus keiyuanensis Proboscidea Gomphotheriidae Tetralophodon cf. xiaolongtanensis Perissodactyla Rhinocerotidae Chilotherium (Subchilotherium) intermedium Artiodactyla Tayassuidae Pecarichoerus sminthos Suidae Suinae Hippopotamodon cf. hyotherioides Tetraconodontinae Parachleuastochoerus sinensis Conohyus sindiensis Tragulidae Dorcatherium sp. Bovidae

Measurements (in mm) of the teeth of ?Lufengpithecus keiyuanensis and cf. Lufengpithecus chiangmuanensis, (a, Woo, 1957 [18]; b, Woo, 1958 [19]; c, Zhang, 1987 [21]; d, Chaimanee et al., 2003 [2]; e, Kunimatsu [original data] (measurements are to one significant figure).

Mesures (en mm) des dents de ?Lufengpithecus keiyuanensis et de celles de cf. Lufengpithecus chiangmuanensis, (a, Woo, 1957 [18] ; b, Woo, 1958 [19] ; c, Zhang, 1987 [21] ; d, Chaimanee et al., 2003 [2] ; e, Kunimatsu [données originales])

Tooth Xiaolongtan Chiang Muan I1/ 12 × 8.9 (d) I2/ 5.8 × 6.5 (c) 5.1 × 4.6 (d) 5.9 × 6.3 (c) Cm/ 10.5 × 8.7 (c) 10.6 × 10.5 (d) 9.9 × 8.5 (c) Cf/ 9.1 × 8.5 (d) P3/ 7.9 × 10.4 (c) 7.2 × 9.9 (d) 8.1 × 9.7 (c) P4/ 7.2 × 11.1 (c) 10.3 × 11 (d) 6.4 × 10.5 (c) M1/ 10.0 × 11.3 (c) 10.0 × 10.5 (c) M2/ 11.3 × 12.8 (c) 10 × 10.4 (d) 10.5 × 11.2 (c) 11.4 × 14.0 (e)* M3/ 11.0 × 12.1 (c) 8.8 × 10.2 (d) 10.3 × 10.7 (c) i/1 5.1 × 5.3 (d) i/2 c/m c/f p/3 10.9 × 9 (b) >12.0 × 8.6 (d) --  × >8.0 (d) p/4 9.0 × 9.5 (b) 12.6 × 13.5 (d) 8.1 × 9.3 (b) 8.7 × 7.9 (d) m/1 11.8 × 10.5 (b) -- × 9.8 (e)* 11.0 × 9.3 (c) m/2 11.8 × 10.0 (a) 14.4 × 12.8 (d) 11.8 × 10.2 (a) 14.0 × 11.8 (d) 13.5 × 12.1 (b) 11.6 × 9.4 (d) 12.7 × 11.5 (c) m/3 12.0 × 10.0 (a) 15.8 × 12.8 (d) 14.2 × 11.9 (b) -- × 12.7 (d) 13.0 × 11.5 (c)

these teeth could be M1/ and m/2 rather than M2/ and m/1.