The first Choerolophodon (Proboscidea, Gomphotheriidae) skull from China

Here we report the first discovery of a relatively complete skull of Choerolophodon from the late early Miocene Dalanggou quarry of Linxia Basin, Gansu Province in China. The skull is low and elongated, with two enamel-less and outward-and-upward curved incisors and the choerolophodont molars. These characters indicate that the new specimen can be assigned to the genus Choerolophodon, as it is quite distinct from other common gomphotheres in northern China such as Gomphotherium, Platybelodon, and Sinomastodon. The skull is also primitive in possessing laterally-expanded zygomatic arches, anteriorly-positioned orbits, weakly-developed cheek teeth cement, and retention of a P4. Prior to this discovery, Choerolophodon was found primarily from the middle-late Miocene of Africa, Eastern Europe, and western and southern Asia. The discovery of this new material expands the known temporal and spatial distributions of this taxon and helps us better understand the phylogeny, evolution, and adaptive radiation of gomphotheres in early Miocene of China.