New fossils of Eucladoceros boulei (Artiodactyla, Mammalia) from Early Pleistocene Nihewan Beds, China

Abstract

Recent excavations at Shanshenmiaozui site in Nihewan Basin of North China uncovered a rich collection of comb-antlered deer, which includes the first discovery of the yearling antler, complete upper and lower dentitions (both deciduous and permanent), associated limb bones including the longest metapodials ever recovered. Based on toothrow length and the dental characters as well as the postcranial bones, the new fossil materials can be referred to Eucladoceros boulei that is estimated to be 350kg and represents the largest Pleistocene cervid ever recovered in China. Besides the large size, E. boulei is also characterized by the pronounced anterior cingulids and entostylid ribs on lower molars as well as the moderately pachyostosed mandibles. The present study shows that the body weight of large cervids can be estimated by the length of toothrow and metacarpal, with exception for Cervus elaphus, which has larger toothrow length, but shorter metacarpal and smaller body size. E. boulei is a typical element of the Early Pleistocene fauna in northern China. The early Villafranchian is a bottleneck period for cervid evolution in northern China, which is characterized by the following features: decrease of cervid diversity, disappearance of archaic groups, and the rise of the medium to large-sized three-tined cervini taxa. The sudden appearance of the very large and/or multi-tined cervids at the Pliocene–Pleistocene transition may represent a great migration event of mammals. The Early Pleistocene cervids from Nihewan Basin are very diverse, and are in need of more taxonomic work.