Brachypotherium perimense (Perissodactyla, Rhinocerotidae) from the Miocene of Nakhon Ratchasima, Northeastern Thailand, with comments on fossil records of Brachypotherium

ABSTRACT

The cranio-dental and postcranial remains of the Rhinocerotidae collected from the sand pit no. 8 at Nakhon Ratchasima in northeastern Thailand, are described in this study. The remains show cheek teeth that tend to have flattened buccal walls, bucco-lingually broad molariform premolars with short crochet, and brachypodal limb bones, suggesting that these remains belong to genus Brachypotherium. Compared with Afro-Eurasian Brachypotherium, the remains are identified as a South Asian species, Brachypotherium perimense. The result reveals that B. perimense was distributed in Southeast Asia during the Late Miocene. The fossil records of Brachypotherium in Afro-Eurasia show that the genus Brachypotherium was already present in the Indian Subcontinent by the earliest Miocene. This genus then became widely distributed and diversified in Afro-Eurasia during the late Early Miocene and Middle Miocene. Its diversity seems to have decreased before it became extinct by the end of the Miocene, with only the African species, B. lewisi, surviving.

KEYWORDS:

• Palaeobiogeography
• Perissodactyla
• Southeast Asia
• Thailand

Acknowledgments

We are grateful to Chavalit Vidthayanon (Bangkok, Thailand), Yupa Thasod (Chiang Mai University, Thailand), Rattanaphorn Hanta (Suranaree University of Technology, Thailand), and all staffs of Khorat Fossil Museum for fossil collection and preparation. The first author thanks Tao Deng, Dan-Hui Sun, and Jiangzuo Qigao (Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China), Emma Bernard (British Museum of Natural History, London, UK), Christine Argot (Muséum National d’Histoire Naturelle Paris, France), Hajime Taru (Kanagawa Prefectural Museum of Natural History, Odawara, Japan) and all staff of Kenya National Museums for helping access to specimens for the comparative works. We wish to thank Editor in chief Gareth Dyke and two anonymous reviewers, whose comments improved the original manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

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Additional information

Funding

This work was supported by the Fujiwara Natural History Foundation [A grant of Fujiwara Natural History award to 2016 and 2018]; Japan Society for the Promotion of Science [KAKENHI Grant Number 18K13648 Grant-in-Aid for Early-Career Scientists].