The first Asian record of the mouse-deer Afrotragulus (Ruminantia, Tragulidae) reassess its evolutionary history and offers insights on the influence of body size on Afrotragulus diversification

ABSTRACT

New fossils of the Miocene crown-tragulid Afrotragulus from Chinji and Dhok Pathan Formations of the Pakistan Siwaliks Group represent its first record out of Africa. This material from Babri Wala (ca. 12.6 Ma), Hasnot 6 (ca. 6.5 Ma) and Barnum Brown’s B 51 classic locality (ca. 13.7 Ma) constitutes three new species, Afrotragulus akhtari, A. moralesi and A. megalomilos. We reassess Afrotragulus ingroup phylogeny recovering two clades with African and Asian representatives. Our results reject the existence of a strictly African lineage in the genus. Body-size estimates show three tiny Afrotragulus with a size corresponding to the lower spectrum of extant Tragulus. However, both Afrotragulus lineages produced species larger than 10 kg. Previously considered very small tragulids, these new forms demonstrate that size range of Afrotragulus equals that of all living tragulids. The smallest forms could be frugivorous/browsers but A. megalomilos and A. moralesi could be opportunistic feeders, specially accounting for their highly derived dentition. These new Asian Afrotragulus extend the biochronological range of the genus from the lower Miocene to the late upper Miocene. Afrotragulus is surprisingly uncovered here as one of the longest-lived and most successful members of the Tragulidae, existing during ca. 13.5 million years (20–6.5 Ma).

KEYWORDS:

• Africa
• Asia
• Ruminantia
• Tragulidae
• body size
• Afrotragulus

Abbreviations

AMNH American Museum of Natural History, New York

BMNH and NHM Natural History Museum, London

GSN Geological Survey of Namibia, Windhoek, Namibia

MNCN-CSIC Museo Nacional de Ciencias Naturales-CSIC, Madrid

MAUV Museo Anatómico de la Universidad de Valladolid, Valladolid

MNHN Muséum National d’Histoire Naturelle, Paris

NMK National Museums of Kenya

PUPC Punjab University Palaeontological Collection

SMNS Staatliche Museum für Naturkunde Stuttgart, Stuttgart; UM, Uganda Museum, Kampala, Uganda

Acknowledgments

IMS thanks Job Kibii (National Museums of Kenya) for granting us permission to photograph the tragulid material (‘D’. pigotti) from Maboko, and specially acknowledges Marta Pina (Manchester University, UK) for taking the actual pictures that allowed us to code the morphological characters of that material. IMS and VQ want to thank the AMNH curators of the Departments of Palaeontology and Mammalogy for accessing us grant over the years to study the collections in their care, including the Siwaliks Group and extant tragulid collections. We also thank Helke Mocke (Geological Survey of Namibia, Windhoek), Sarah Musalizi (Uganda Museum, Kampala), Pip Brewer (NHM, London) and Christine Argot (MNHN, Paris) for providing access to the fossil collections of their respective institutions. Thanks to Denis Geraads (CNRS, France) for the pictures of the Afrotragulus hemimandible KNM SO 1345 (Songhor, Kenya). We also acknowledge Nikos Solounias (College of Osteopathic Medicine, New York Institute of Technology, USA) for his help with the Greek language and the naming of A. megalomilos sp. nov. Thanks to Pablo Peláez-Campomanes (MNCN-CSIC) for his help with the stratigraphy, to Martin Pickford (CNRS) for providing us of many Miocene African tragulids to study and make us part of the Namibia Palaeontological Expedition, and to Marco Ansón for giving us permission to use his illustrations of Tragulus and Hyemoschus. We thank John C. Barry (Harvard University, USA) for providing the palaeomagnetic data of site B 51, and Sergio Almécija and Chris Gilbert (both AMNH) for their invaluable help with the new photographs of AMNH 19310 that have been used in the present work. SGA is grateful to Mr. Allah Yaar Khan and his family for their hospitality during fieldwork, and also to Mr. Muhammad Khan for his guidance on the field in the Kohtehra area. Finally, we want to thank the reviewers of this work (Ari Grossman and two anonymous reviewers) for their comments that greatly improved the quality of the manuscript.

This work pays homage to the career of Prof. Jorge Morales (MNCN-CSIC). IMS, VQ and DDM want to thank Jorge for so many years of mentorship, friendship and, of course, fossils. Thanks for supervising our doctoral theses and in the process instilling in us the love for the evolution of the fascinating and challenging ruminants. Thanks for so many excavations and discussions. It has been—and always shall be— an honour to work with you.

Disclosure statement

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

Data availability statement

This work and the nomenclatural acts it contains have been registered in Zoobank: 7FC6D555–D653–4632–A8BE–FCB4A88A8482

Supplementary material

Supplemental data for this article can be accessed here.

Additional information

Funding

This work was supported by the Spanish Government Agencia Estatal de Investigación–European Regional Development Fund of the European Union (projects MINECO/FEDER-UE; CGL2016-76431-P and CGL2017-82654-P, AEI/FEDER EU), the Generalitat de Catalunya (CERCA Programme), the Spanish Research Projects I+D+i PID2020-117289GBI00 and I+D+i PID2020-117289GBI00 funded by MCIN/AEI/10.13039/501100011033, and the Research Groups CSIC 64 1538 and CAM-UCM 910607;Generalitat de Catalunya CERCA programme;MCIN/AEI/10.13039/501100011033/;