A shelduck coracoid (Aves: Anseriformes: Tadorna) from the arid early Pleistocene of the Qinghai-Tibetan Plateau, China

Abstract

An avian coracoid from the early Pleistocene Qigequan Formation in the Qaidam Basin, Qinghai Province, China, in the northern part of the Qinghai-Tibetan Plateau represents one of the few avian fossils from the region. The specimen is from an individual of a shelduck (Tadorna sp.), and its phylogenetic position is supported by the presence of a procoracoid notch (where the procoracoid foramen is greatly reduced) and other osteological characters. The previous hypothesis of extreme aridity in the Qaidam Basin during the early Pleistocene is lessened by the presence of a shelduck (along with the fossil record of proboscideans) that is part of a clade that occurs and breeds on the arid Qinghai-Tibetan Plateau today. In addition, the occurrence of Chinese shelducks in arid environments today likely evolved in combination with the increase in elevation and intensifying aridity in the plateau region since the early Pleistocene.