Segisaurus (meaning "Segi canyon lizard") is a genus of small coelophysoid theropod dinosaur, that measured approximately 1 metre (3 feet) in length. The only known specimen was discovered in 1933 in early Jurassic strata in Tsegi Canyon, Arizona, for which it was named. Segisaurus is the only dinosaur to have ever been excavated from the area. It was later described in 1936 by the paleontologist Charles Lewis Camp. The fragmentary fossil skeleton consisted of portions of the limbs, pelvis, and vertebrae, but no cranial material was located. Segisaurus appears to have been closely related to the better-known Coelophysis. One distinction, however, was that Segisaurus had solid bones, while those of Coelophysis'were hollow. This even made some scientists consider if Segisaurus was even a theropod at all. Later investigations into the specimen in 2005 showed that Segisaurus did in fact have hollow bones, and lead scientists to believe that Segisaurus was related more closely to Procompsognathus.

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