Middle Eocene primate tarsals from China: implications for haplorhine evolution.

We describe tarsal remains of primates recovered from the Middle Eocene (approximately 45 mya) Shanghuang fissures in southern Jiangsu Province, China. These tarsals document the existence of four higher-level taxa of haplorhine primates and at least two adapid species. The meager and poorly preserved adapid material exhibits some similarities to European adapines like Adapis. The haplorhine primates are divided into two major groups: a "prosimian group" consisting of Tarsiidae and an unnamed group that is anatomically similar to Omomyidae; and an "anthropoid group" consisting of Eosimiidae and an unnamed group of protoanthropoids. The anthropoid tarsals are morphologically transitional between omomyids (or primitive haplorhines) and extant telanthropoids, providing the first postcranial evidence for primates which bridge the prosimian-anthropoid gap. All of the haplorhines are extremely small (most are between 50-100 g), and the deposits contain the smallest euprimates ever documented. The uniqueness of this fauna is further highlighted by the fact that no modern primate community contains as many tiny primates as does the fauna from Shanghuang.