Skeleton of early Eocene Homogalax and the origin of Perissodactyla

Kenneth D. Rose

The first good skeletal remains of Homogalax protapirinus from the Wasatchian of the Bighorn Basin, Wyoming, indicate that this primitive tapiromorph was more plesiomorphic in many features than primitive equoids including Hyracotherium. Compared to Hyracotherium, Homogalax more closely resembles Phenacodonta (the closest outgroup of Perissodactyla for which postcrania are known) in various details of articular surfaces, muscle attachments, and proportions of the humerus, manus, and pes.Among known taxa, Homogalax most nearly approximates the plesiomorphic postcranial skeletal anatomy of Perissodactyla.