Eutheriodontia
The Eutheriodontia are a clade of therapsids that includes therocephalians and cynodonts.
The clade was named in 1986 by James Allen Hopson and Herbert Richard Barghusen, the name meaning the "True Theriodontia". Within Hopson's system, the Eutheriodontia are the sister group of the Gorgonopsia within the Theriodontia. A close relationship between therocephalians and cynodonts had been recognized for many years. In 2001 the Eutheriodontia were defined as the least inclusive clade including Mammalia and Bauria.
Therocephalians and cynodonts are thought to have diverged in the Middle Permian, and each group independently evolved mammal-like features, including a secondary palate and the loss of a postorbital bar. Mammalian features that both groups inherited from a common ancestor include the loss of teeth on the palate, the expansion of the epipterygoid bone at the base of the skull, and the narrowing of the skull roof to a narrow sagittal crest running between large temporal openings.
