pelycosaurgrade

Pelycosaur-grade refers to a category of extinct synapsid reptiles that lived during the Permian and Triassic periods, approximately 299 to 201 million years ago. These animals are characterized by their distinctive skull structure, which includes a large, triangular opening called the antorbital fenestra, and a large temporal fenestra behind the eye socket. The term "pelycosaur-grade" is used to describe a broader group of synapsids that share these features, rather than a specific taxonomic group.

Pelycosaur-grade animals include several well-known groups, such as the pelycosaurs, which were early synapsids with a diverse range of body sizes and forms, and the therapsids, which eventually gave rise to mammals. The term is often used in paleontology to discuss the evolutionary relationships and transitions between these early synapsids and later groups, such as the therapsids and mammals.

The study of pelycosaur-grade animals is important for understanding the early evolution of mammals and the broader history of synapsid reptiles. Fossils of these animals have been found on all continents, providing valuable insights into the global distribution and diversity of these early reptiles.