page_title: Dimetrodon
section_title: Skin
hierarchical_section_title: Dimetrodon / Description / Skin
caption_attribution_description: English: A modern reconstruction of Dimetrodon Grandis. The integument is based on evidence from Dimetropus and Estemmenosuchus showing it may have had scaleless skin with rectangular scutes on the underside of the belly. The upright posture is also based on the Dimetropus trackways, which shows Dimetrodon and closely related synapsids may have stood with its legs underneath the body rather than sprawling.
context_page_description: Dimetrodon is an extinct genus of non-mammalian synapsids that lived during the Cisuralian, around 295–272 million years ago. 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 erected in 1878.
  Dimetrodon is often mistaken for a dinosaur or as a contemporary of dinosaurs in popular culture, but it became extinct some 40 million years before the first appearance of dinosaurs. Reptile-like in appearance and physiology, Dimetrodon is nevertheless more closely related to mammals than to modern reptiles, though it is not a direct ancestor of mammals. Dimetrodon is assigned to the "non-mammalian synapsids", a group traditionally called "mammal-like reptiles".
context_section_description: No fossil evidence of Dimetrodon's skin has yet been found. Impressions of the skin of a related animal, Estemmenosuchus, indicate that it would have been smooth and well-provided with glands, however this form of skin may not have applied to Dimetrodon as its lineage is fairly distant. Dimetrodon also may have had large scutes on the underside of its tail and belly, as other synapsids did. Evidence from the varanopid Ascendonanus suggests that some early synapsids may have had squamate-like scales. However, recent studies have recovered varanopids as taxonomically closer to diapsid reptiles.
caption: Dimetrodon grandis in an upright posture based on Dimetropus tracks, with scaleless skin and scutes on its underside
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