Theriodontia

Eutheriodontia

Theriodont. 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.