New fossil remains of Rhinocerotidae (Perissodactyla) from the early Late Miocene Tebingan area, central Myanmar

ABSTRACT

New fossil remains of Rhinocerotidae, dated from the early Late Miocene, were discovered from the lowermost part of the Irrawaddy Formation in the Tebingan area, Magway Region, central Myanmar. The Tebingan rhinoceros fossils, consisting of isolated teeth, maxillae, and mandibles, are assigned to three taxa: Brachypotherium perimense defined by a constricted protocone, a well-developed parastyle and broad upper teeth, to ‘Brachypotherium’ fatehjangense with a flat ectoloph, crochet, and the absence of tubercle at the entrance of the median valley. Other specimens were assigned to Rhinoceros sp. due to having a developed parastyle, crochet and a strong anterior cingulum and the absence of a constricted protocone and ante-crochet. The evolutionary history of Rhinocerotidae is poorly known in Southeast Asia, and few rhinoceros’ species have been identified from the Irrawaddy Formation. The newly identified Rhinoceros specimens from the early Late Miocene Tebingan area are the oldest fossil records for Rhinoceros in Southeast Asia. The Tebingan mammal fauna is similar to the Nagri and Dhok Pathan faunas of the lower/middle Siwaliks of the Indian subcontinent, indicating the faunal exchange between these two regions in the late Neogene.

KEYWORDS:

• Rhinoceros
• brachypotherium
• irrawaddy formation
• neogene
• palaeobiogeography
• southeast asia

Acknowledgments

We gratefully thank the personnel of the Ministry of Education and the Ministry of Culture of the Union of Myanmar for granting our permissions for fieldwork in Myanmar. We also thank all members of the Myanmar-Japan joint Paleontological Research Team and the curators of the National Museum of Myanmar for their assistance, and for providing us with access to their specimens. We would like to thank María Esperanza Cerdeño (Instituto Argentino de Nivología, Glaciología y ciencias abientales, Mendoza, Argentina), Abdul Majid Khan (University of the Punjab, Lahore, Pakistan), Luca Pandolfi (University of Florence, Florence, Italy) for providing us the literature necessary to create this publication; and Naoto Handa (Nara Women’s University, Nara, Japan) and Pierre-Olivier Antoine (Université de Montpellier, Montpellier, France) for their inspiring discussions and comments. We also thank Nao Kusuhashi (Ehime University, Matsuyama, Japan) for preparing the map of the study area. We would like to thank Editor in chief Gareth Dyke and three anonymous reviewers for their comments to improve the original manuscript. This study was supported by JSPS KAKENHI (No. 22H02708 to M. Takai and No. JP22KK0048 to S. Tomiya), and by the Yamada Science Foundation (No. 1071 to M. Takai).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Japan Society for the Promotion of Science [No. 22H02708]; Yamada Science Foundation [No. 1071].