Pelycodus

Abstract: More than one hundred undescribed foot elements of Cantius and other closely related notharctine adapids (7 species in all) from throughout the early Eocene (Wasatchian) Willwood Formation of the Bighorn Basin, Wyoming, have been analyzed. For four species (Cantius ralstoni, “Copelemur” feretutus, Cantius frugivorus, and? Pelycodus jarrovii) these represent the first described postcranial material. The clade of Cantius and allied genera in the Bighorn Basin includes several speciation events and both increases and decreases in body size. The largest species represented by tarsal remains (? Pelycodus jarrovii) is several times larger than the smallest, Cantius ralstoni. However, despite the number of species, temporal duration, and range of body size represented, there are no obvious changes in foot morphology as measured by various indices or by observation of qualitative features. This contrasts with the more obvious changes in dental features (e.g., development of hypocone and mesostyle) in the same group of species described by earlier authors. The fossil record of Cantius thus illustrates different kinds of evolutionary change in the dentition and tarsus. The dentition changes in both size and shape while the tarsus changes only in size. We describe significant differences in foot anatomy which distinguish notharctines from extant strepsirhines, including the nature of the articulations between the navicular and cuboid and the distal tarsus with the metatarsus. These features indicate that the fossil taxa are not particularly closely allied phylogenetically to either extant strepsirhines in general or lemurids in particular.

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.