Equus qingyangensis in Jinyuan Cave and its palaeozoographic significance

Abstract

The discovery of a fossil Equus skull in Jinyuan Cave, Luotuo Hill, Dalian, is reported herein. The specimen was identified as Equus qingyangensis, based on the complexity of morphological features, and is considered to be as young as 1.2 Ma. Combined with the new finding, the known specimens of E. qingyangensis were reviewed and compared with other stenonid horse species in Eurasia. A skull previously reported as E. teilhardi, unearthed in the Nihewan Basin, is revised as E. qingyangensis. The recorded locations of E. qingyangensis findings are Bajiazui, Nihewan (s. s.), and the Jinyuan Cave. According to paleomagnetic data, mammalian fauna correlations, and significant environmental events, the ages of the Bajiazui and Nihewan (s. s.) localities are considered to be 2.1–1.7 Ma and correspond with the late Villafranchian faunae in Europe. Thus, based on the records, the temporal range of E. qingyangensis is 2.1–1.2 Ma. With climate change and exposure of the Bering Strait, the occurrence of E. qingyangensis in China was a significant biotic event. E. qingyangensis and another gracile species, E. stenonis, appeared and dispersed throughout Eurasia, and wolf-like canids and the large hyenid Pachycrocuta emerged during this period. Considering the roles equid and canid species played, we propose that this Equus–Canis occurrence represented a substantial biotic event during a series of major environmental and ecological changes.