TRITYLODONT

any member of a genus (Tritylodon) of extinct, advanced mammallike reptiles found as fossils in Late Triassic rocks in southern Africa (the Triassic period began about 245 million years ago and ended about 208 million years ago). Tritylodonts are characterized by a distinctive dentition: the anterior incisors are separated from the complicated cheek teeth by a pronounced gap; the cheek teeth possess two to four rows of cusps arranged longitudinally. In features of skull construction and general overall skeletal construction the tritylodonts closely approached true mammals, though they were too specialized to have given rise to the mammals and may have been contemporary with some of the earliest of them. In jaw construction and articulation tritylodonts were still therapsid reptiles; the lower jaw still retains reptilian components rather than the single bone, the dentary, that is characteristic of the mammals. It is probable that the habits of Tritylodon were similar to those of the later rodents and multituberculates.