CONDYLARTHRA

extinct order of hoofed mammals that includes the ancestral forms of later, more advanced ungulates (hoofed mammals with a plant diet). The condylarths are transitional between the insectivores and advanced ungulates. The condylarths existed mostly in the Paleocene Epoch (66.4 to 57.8 million years ago), but some forms persisted through the Eocene Epoch into the Early Oligocene (until 30 million years ago). The origins of the condylarths seem to lie in the Cretaceous Period; a Late Cretaceous form is the genus Protungulatum, which appears to be the oldest known ungulate. A well-known condylarth genus is Phenacodus, an Eocene form that grew to be as large as a modern tapir. The condylarths were a diverse group that developed a great many traits of adaptive significance. Some forms remained relatively small, while others attained large size. The teeth of some of the condylarths appear almost carnivore-like.