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Artist's rendering of Edaphosaurus pogonias - Distant Relative of Living Mammals

Edaphosaurus pogonias
Sailback

Incomplete vertebral column
TMM 40005-1
Arroyo Formation, Permian
Baylor County, Texas


Edaphosaurus is a distant extinct relative of living mammals.  Like Seymouria, another Permian fossil that can be found in the Dino Pit, it dates back roughly 280 million years.  Edaphosaurus belongs to the great lineage known as Synapsida, which includes all living species of mammals and their extinct relatives. 

Like its more famous relative Dimetrodon, Edaphosaurus had a sail-like fin that was supported by bones of the vertebral column.  Edaphosaurus differs from Dimetrodon in having cross-bars on the spines that supported its fin.  The function of the fin has always perplexed scientists.  Some have argued that it was for thermoregulation and that the great surface area provided by the fin was used to more rapidly warm the animal to the level where it could be active.  Others have argued that the fin was analogous to antlers and horns in some modern mammals, and that it was used in species recognition and courtship.  Both explanations may be correct. 

The redbeds of Baylor County and surrounding counties are the richest in the world for fossils of Early Permian age.  These rocks hold a unique record of early synapsid history and have been visited by paleontologists from all over the world.  Edaphosaurus is among the rarest synapsids, and most of the specimens that have been discovered consist of little more than fragments of its skeleton.  Based on its teeth, it is commonly thought that Edaphosaurus was herbivorous, but we know little of its habits. 

The Edaphosaurus specimen buried in the Dino Pit was cast from an original collected in 1944 by H. J. Sawin and E. Jones.  The only part of the specimen that is preserved is a part of the backbone that includes some of the spines that supported the fin, but it is one of the most complete examples of Edaphosaurus on record. 

 

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