Abstract
Faunal provincialism between the North and South parts of Eastern Asia is shown to have been in place since the late Eocene. This provincialism structured the mammalian dispersals across Eurasia for millions of years and provides insights into both palaeonvironments and palaeoclimate zonation. In addition, this study reveals the oldest record of a crown ruminant (Iberomeryx from Shinao, China). Ecologically, as well as economically, ruminant artiodactyls are one of the most important large mammal groups today. The revision of the ruminants from the Shinao Formation, from the Caijiachong marls and Xiaerhete, resulted in two new taxa and shows that the different provinces were populated by distinct taxa living in different environments, dominated by the monsoon in the South and drier conditions in the North. Evaluating this result in a Eurasian context demonstrates that the dispersals from Asia to Europe was complex. These results confirm that there were at least two dispersal events, distinct in space and time: the Grande-Coupure from Northern and Central Asia along the North ca. 34 Mya and the Bachitherium dispersal event from the Southern province along a southerly route ca. 31 Mya.
Highlights
The fossil record of Asia holds most of the spectacular findings in vertebrate palaeontology of the several last decades and many questions in mammal evolution can be tackled thanks to these discoveries
The oldest lophiomerycid appeared during the late middle Eocene (Zhailimeryx hetii14) and did not diversify until the late Eocene and Oligocene when
The family was distributed across the whole of Eurasia before it disappeared during the latest O ligocene[14,15,16]
Summary
The fossil record of Asia holds most of the spectacular findings in vertebrate palaeontology of the several last decades and many questions in mammal evolution can be tackled thanks to these discoveries. To K. primitivus, the described specimens differ from Z. jingweni in its lower molar lingual cusps being more laterally compressed, and in an entoconid that is slightly shifted to anterior with respect to the hypoconid, while it is more posterior in Z.
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