Palaeoenvironment examination of the terminal Miocene hominoid locality of the Zhaotong Basin, southwestern China, based on the rhinocerotid remains

Abstract

Anatomic modification in evolution process of mammals was closely correlated with the environmental changes, and become the powerful evidence for reconstructing the palaeoenvironment shaped their evolution. Rhinocerotid fossils are important indicators of the ecosystems inhabited by the mammalian faunas. Here, we first described remains of two rhinocerotids from the terminal Miocene Zhaotong Basin, the most recent hominoid locality in South China, including Acerorhinus lufengensis and Rhinocerotini gen. et sp. indet. New remains of A. lufengensis display a short crochet and antecrochet, expanded lingual cones, and rounded labial wall of the trigonid and talonid. These characteristics demonstrate its feeding habits of grazing brush and high grass. The limb bones of Rhinocerotini gen. et sp. indet. enable to live in an open habitat in having the following characteristics: the Mc II facet of Mc III is large, oval, flattened, and nearly vertical in direction; the femur exhibits a very large trochanter tertius and two nearly parallel asymmetrical ridges of the distal patella trochlea. The rhinocerotid fossils described herein provide a substantial evidence of the presence of mosaic environment, and the grassland should patches within or along the margin of the forest in the terminal Miocene Shuitangba locality.