Article: The Lower Permian synapsid Glaucosaurus from Texas
The early synapsid Glaucosaurus megalops, from the Lower Permian of north-central Texas, is re-examined. Despite being represented by a single, partial skull of uncertain ontogenetic age, the presence of six autapomorphies indicates that Glaucosaurus is clearly a distinct synapsid form. Phylogenetic analysis of the early Synapsida indicates that Glaucosaurus is the probable sister taxon of Edaphosaurus within Edaphosauridae. The clade of Glaucosaurus and Edaphosaurus is distinguished from its sister taxon lanthasaurus by five synapomorphies: (1) premaxillary teeth equal to maxillary teeth in size, (2) caniniform region absent, (3) caniniform tooth absent, (4) prefrontal ventral process expanded transversely, and (5) transverse flange of pterygoid absent.