An additional hole in the skull, the supratemporal fenestra, can be seen when viewed from above. The back of the skull is oriented at a slight upward angle, a feature that it shares with all other early synapsids.
The skull of Dimetrodon Limbatus is tall and compressed laterally, or side-to-side. The eye sockets are positioned high and far back in the skull. Behind each eye socket is a single hole called an infratemporal fenestra.
Single openings in the skull behind each eye, known as temporal fenestrae, and other skull features distinguish Dimetrodon and true mammals from most of the earliest sauropsids.
Gorgonopsia is an extinct clade of sabre-toothed therapsids from the Middle to Upper Permian roughly 265 to 252 million years ago. They are characterised by a long and narrow skull.