<P> Dimetrodon ( / daɪˈmiːtrədɒn / ( listen ) or / daɪˈmɛtrədɒn / , meaning `` two measures of teeth '' ) is an extinct genus of synapsids that lived during the Cisuralian ( Early Permian ) , around 295 -- 272 million years ago ( Ma ) . It is a member of the family Sphenacodontidae . The most prominent feature of Dimetrodon is the large neural spine sail on its back formed by elongated spines extending from the vertebrae . It walked on four legs and had a tall , curved skull with large teeth of different sizes set along the jaws . Most fossils have been found in the southwestern United States , the majority coming from a geological deposit called the Red Beds of Texas and Oklahoma . More recently , fossils have been found in Germany . Over a dozen species have been named since the genus was first described in 1878 . </P>
<P> Dimetrodon ( / daɪˈmiːtrədɒn / ( listen ) or / daɪˈmɛtrədɒn / , meaning `` two measures of teeth '' ) is an extinct genus of synapsids that lived during the Cisuralian ( Early Permian ) , around 295 -- 272 million years ago ( Ma ) . It is a member of the family Sphenacodontidae . The most prominent feature of Dimetrodon is the large neural spine sail on its back formed by elongated spines extending from the vertebrae . It walked on four legs and had a tall , curved skull with large teeth of different sizes set along the jaws . Most fossils have been found in the southwestern United States , the majority coming from a geological deposit called the Red Beds of Texas and Oklahoma . More recently , fossils have been found in Germany . Over a dozen species have been named since the genus was first described in 1878 . </P>
dinosaur with fin on back walks on 4 legs
dinosaur with fin on back walks on 4 legs
Dimetrodon
Dimetrodon