Phylum: Chordata

Class: Synapsida
Family: Sphenacodontidae
 (Dimetrodon)

" Dimetrodon  was a predatory animal that flourished during the Permian period, living between 280-265 million years ago. It was more closely related to mammals than to true reptiles such as lizards."  Wikipedia entry.
Dimetrodon sail bones Formation: Vale Period: Permian Location: Knox Co., TX.  April 23, 2011.
Whiteside Museum of Natural History Seymour, Tx.	Whiteside Museum of Natural History Seymour, Tx.