Gymnarthrids

Cardiocephalus is an extinct genus of microsaurian tetrapods from the Permian period. It was a member of the family Gymnarthridae.

Gymnarthridae is an extinct family of the group Recumbirostra. Gymnarthrids are known from Europe and North America and existed from the Late Carboniferous through the Early Permian. Remains have been found from the Czech Republic, Nova Scotia, Illinois, Texas, and Oklahoma. Previously they were considered tuditanomorph microsaurs.