Species of Allosaurus - Misassigned Species

Misassigned Species

Several species initially classified within or referred to Allosaurus do not belong within the genus. A. medius was named by Marsh in 1888 for "various specimens" from the Early Cretaceous of Maryland, although most of the remains were removed by Richard Swann Lull to the new ornithopod species Dryosaurus grandis, except for a tooth. Gilmore considered the tooth nondiagnostic but transferred it to a new species, Dryptosaurus medius. The referral was not accepted in the most recent review, and Allosaurus medius was simply listed as a dubious species of theropod. Allosaurus sibiricus was described in 1914 by A. N. Riabinin on the basis of a bone, later identified as a partial fourth metatarsal, from the Early Cretaceous of Buryatia, Russia. It was transferred to Chilantaisaurus in 1990. This is not the only report of Allosaurus from Siberia, or Asia in general. Kurzanov and colleagues in 2003 designated six teeth from Siberia as Allosaurus sp. (meaning the authors found the specimens to be most like those of Allosaurus, but did not or could not assign a species). Also, reports of Allosaurus in Shanxi, China go back to at least 1982, and tail vertebrae from Datong in Shanxi have been assigned to A. sp.

Allosaurus meriani was described in 1870 by Greppin as a species of Megalosaurus, based on a tooth from the Late Jurassic of Switzerland. It has occasionally been referred to Allosaurus, but recent reviews have listed it as dubious theropod species Megalosaurus meriani, or included it in Ceratosaurus sp. Allosaurus stechowi was described in 1920 by Janensch as Labrosaurus stechowi for isolated Ceratosaurus-like teeth from the Tendaguru beds of Tanzania. With the synonymization of Labrosaurus and Allosaurus, Donald F. Glut listed it as a species of Allosaurus, but it is now either assigned to Ceratosaurus sp. or considered a dubious ceratosaurian.

There are also several species left over from the synonymizations of Creosaurus and Labrosaurus with Allosaurus. Creosaurus potens was named by Lull in 1911 for a vertebra from the Early Cretaceous of Maryland. It is now regarded as a dubious theropod. "Labrosaurus huene" is an informal name used by von Huene (1956, 1958) for a tooth from the Late Jurassic of Szechuan, China, and L. fragilis is a typographical error by Marsh (1896) for Labrosaurus ferox. L. sulcatus, named by Marsh in 1896 for a Morrison theropod tooth, which like L. stechowi is now regarded as either Ceratosaurus sp. or a dubious ceratosaurian.

A. tendagurensis was named in 1925 by Werner Janensch for a partial shin (HM 67) found in the Kimmeridgian-age rocks of Tendaguru, in Mtwara, Tanzania. This species has not had strong support in recent years, with opinions on its identity ranging from a tentatively valid species of Allosaurus, to a basal tetanuran, to simply a dubious theropod. The most recent analysis has placed it in Carcharodontosauridae. Although obscure, it was a large theropod, possibly around 10 meters long (33 ft) and 2.5 metric tons (2.8 short tons) in weight.

Read more about this topic:  Species Of Allosaurus

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