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Dimetrodon

Dimetrodon
Temporal range: Cisuralian, 295–272 Ma
Dimetrodon incisivum 01.jpg
Skeleton of D. incisivum, Staatliches Museum für Naturkunde Karlsruhe
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Synapsida
Family: Sphenacodontidae
Subfamily: Sphenacodontinae
Genus: Dimetrodon
Cope, 1878
Type species
Dimetrodon limbatus
Cope, 1877
(originally Clepsydrops limbatus)
Species

See below

Synonyms

See below

Dimetrodon (Listeni/dˈmtrədɒn/; meaning "two measures of teeth") is an extinct genus of synapsid that lived during the Early Permian period, around 295–272 million years ago (Ma). It is a member of the family Sphenacodontidae. The most prominent feature of Dimetrodon is the large 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 in 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.

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 or descendant of mammals.Dimetrodon is assigned to a group traditionally called "mammal-like reptiles"—more recently termed "stem-mammals" or "non-mammalian synapsids". That is, many vertebrate paleontologists today group Dimetrodon together with mammals in an evolutionary group, or clade, called Synapsida, while they place dinosaurs with living reptiles and birds in a separate clade, Sauropsida. Single openings in the skull behind each eye, known as temporal fenestrae, and other skull features distinguish Dimetrodon and mammals from most of the earliest sauropsids.


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Wikipedia

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