Comparative Study of the Calcanea of Members of the Ursidae and Procyonidae

Abstract

Calcanea of all of the bears and all but one genus of procyonids arc compared and described. These calcanea indicate a close similarity of members of these two families. Some arrangement into subgroups can be made in each of the families. In the Ursidae, the calcanea of Ursus maritimus, Tremarctos, and Helarctos are similar; and those of Ursus americanus, Ursus arctos, Selenarctos, Melursus, and Ailuropoda are similar. In the Procyonidae, the calcanea of Procyon and Nasua, Potos and Bassaricyon, and Ailurus and Bassariscus are similar. The degree of development of the trochlear process and the proximal extension of the trochlear shelf is the major difference between members of the two families. Differences arc also evident in the various articular surfaces and the greater tuberosity.