Paleozoic Pals Dimetrodon PlushDimetrodon grandis Permian synapsid Dimetrodon is often mistaken for a dinosaur, but it is actually much more closely related to mammals! It belongs to a group of animals called synapsids, which are distinguished from reptiles by their skull features. Today, mammals are the only living synapsids, but Dimetrodon was one of the earliest members of this group. Primitive synapsids were succeeded by a more advanced group called the therapsids, sometimes