Theriodontia

Theriodonts Temporal range: Middle Permian–Present, 265–0 Ma PreЄ Є O S D C P T J K Pg N
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Order:	Therapsida
Clade:	Neotherapsida
Clade:	Theriodontia Owen, 1876
Groups
†Gorgonopsia Eutheriodontia

Theriodonts ("beast tooth", referring to more mammal-like teeth), are a major group of therapsids. They can be defined in traditional, Linnaean terms, in which case they are a suborder of mammal-like reptiles that lived from the Middle Permian to the Middle Cretaceous, or in cladistic terms, in which case they include not only the traditional theriodonts but also their descendants the mammals as well (in the same way that, cladistically speaking, the theropod dinosaurs include the birds as a sub-clade).

Theriodonts appeared almost the same time as the anomodonts, about 265 million years ago, in the Middle Permian. Even these early theriodonts were more mammal-like than their Anomodont and Dinocephalian contemporaries.

Theriodonts fall into three main groups: Gorgonopsia, Therocephalia and Cynodontia. Early theriodonts may have been warm-blooded. Early forms were carnivorous, but several later groups became herbivorous during the Triassic.

Theriodont jaws were more mammal-like than was the case of other therapsids, because their dentary was larger, which gave them more efficient chewing ability. Furthermore, several other bones that were on the lower jaw (found in reptiles), moved into the ears, allowing the theriodonts to hear better and their mouths to open wider. This made the theriodonts the most successful group of synapsids.