<span>Mammals are advanced synapsids, animals distinguished by having extra openings in the skull behind the eyes; this opening gave the synapsids stronger jaw muscles and jaws (the jaw muscles were anchored to the skull opening) than previous animals.
Synapsids include the mammals, and their ancestors, the pelycosaurs, therapsids, and cynodonts. Pelycosaurs (like Dimetrodon and Edaphosaurus) were early synapsids, they were mammal-like reptiles. Later synapsids include the therapsids and the cynodonts (with multicusped post-canine teeth; they lived from the late Permian through the Triassic period).
The cynodonts led to the true mammals. Over time, the synapsid gait became more upright and tail length decreased</span>
