DIARTHROGNATHUS

genus of extinct, advanced mammal-like reptiles found as fossils in Late Triassic terrestrial deposits in southern Africa (the Triassic Period lasted from 245 to 208 million years ago). Diarthrognathus was contemporaneous with a host of other mammal-like reptiles but is nearer than many of them to the line leading to the true mammals because of its unspecialized features of skeletal anatomy and dentition. The articulation of the lower jaw with the skull shares reptilian and mammalian characteristics.