> Eudora
> Our Universe
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> Tetrapoda (Terrestrial Vertebrates)
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> Crown Tetrapoda
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> Sphenacodontia
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> Sphenacodontoidea
> Ctenorhynchus
Sphenacodontinae
Sphenacodontidae. The skull is long, deep and narrow, an adaptation for strong jaw muscles.
The front teeth are large and dagger-like, whereas the teeth in the sides and rear of the jaw are much smaller (hence the name of the well-known genus Dimetrodon – "two-measure tooth", although all members of the family have this attribute). Several large (~3 meters) and advanced members of this group (Ctenospondylus, Sphenacodon, Secodontosaurus and Dimetrodon) are distinguished by a tall sail along the back, made up of elongated vertebral neural spines, which in life must have been covered with skin and blood vessels, and presumably functioned as a thermoregulatory device. However, possession of a sail does not appear to have been essential for these animals.