Primates from Later Eocene Rocks of Southern California

Abstract

Newly discovered later Eocene (Uintan) primates (adapids, omomyids, and microsyopids) from San Diego Co., California are described and compared with those of other Eocene faunas in Ventura Co. (Sespe Formation) and the North American western interior. The 11 species of primates from San Diego Co. lived in coastal lowland riparian and deltaic environments; their remains are preserved in the Friars and Mission Valley formations (early Uintan, greater San Diego area) and Santiago Formation (later Uintan, northwestern San Diego Co.). Genera previously known from the western interior but recorded for the first time from the west coast include Pelycodus, Notharctus, Hemiacodon , and ? Macrotarsius ; to these is added Omomys , as I consider Stockia powayensis a species of Omomys . Range extensions into the early Uintan include Pelycodus, Notharctus , and Hemiacodon . The southerly climes of the Californian later Eocene coastal areas may have served as temporary havens for species that became extirpated earlier in the western interior. All nine primate species recorded from the early Uintan of the west coast had close relatives in the western interior, a faunal similarity shared by other vertebrates. Late in the Uintan, west coastal endemism increased as barriers to faunal interchange developed between the two areas.