MIACIS

genus of extinct carnivores found as fossils in deposits of early to late Eocene age in North America and of late Eocene age in Europe and Asia (the Eocene Epoch lasted from 57.8 to 36.6 million years ago). Miacis is representative of a group of early carnivores, the miacids, that were the ancestors of the modern carnivores. Miacids retain primitive characteristics present in the creodonts, an older group of mammalian carnivores, such as low skulls, long, slender bodies, long tails, and short legs. Miacis retained the primitive number of teeth, 44, although some reductions in this number were apparently in progress; some of the teeth are reduced in size. The hind limbs were longer than the forelimbs, and the pelvis was very doglike in form and structure. Some specialized traits are present in the vertebrae. Miacis and related forms had brains that were relatively larger than those of the more primitive creodonts; the increase in brain size as compared with body size probably reflects an increase in intelligence. Miacis was probably a forest dweller that preyed upon smaller animals; it was very weasel-like in form.