Hippotherium Datum implies Miocene palaeoecological pattern

Abstract

Here, we report well-preserved skulls and postcranial specimens of genus Hippotherium from the Linxia Basin, Gansu, China. Based on morphological comparison, the species of Hippotherium in China, Hippotherium weihoense and Hippotherium chiai, should be ascribed to the same species, H. weihoense. We also reviewe other Old World hipparion species in the very early Late Miocene and figure out two evolutionary routes: the Hippotherium and Cormohipparion lineages. Analysis of locomotive ability indicates that H. weihoense likely lived in an open habitat, whereas other species of Hippotherium likely lived in closed habitats. This result shows a palaeoecological pattern in the early Late Miocene in Eurasia influenced by a series of geological events as aridification of mid-latitude Asia progressed, whereas Europe and North Africa remained relatively humid. As the genus originated from East Asia, hipparion horses divided rapidly into different groups with differing functional morphology to occupy diverse niches.