Deltadromeus (meaning "delta runner") is a genus of large basal ceratosaurian theropod dinosaur from Northern Africa. It had long, unusually slender hind limbs for its size, suggesting that it was a swift runner. The skull is not known. Two fossil specimens of a single species (D. agilis, or "agile delta runner") have been described, found in the Bahariya Formation and Kem Kem Beds, which date to the mid Cretaceous Period (mid Cenomanian age), about 95 million years ago. It may be a junior synonym of the contemporary Bahariasaurus. Often thought to be a ceratosaurian, the discovery of the theropod Gualicho shinyae indicates it is likely a sister taxon to the South American predator.
Description[]
The fairly complete holotype skeleton of Deltadromeus agilis (museum catalogue number SGM-Din2) measured an estimated 8 m (26.24 ft) long.[2]
A second specimen (IPHG 1912 VIII) was originally described by Ernst Stromer as a specimen of Bahariasaurus,[3] but was designated as a specimen of Deltadromeus by Paul Sereno in 1996.[4] This second specimen comes from a much larger individual, with a femur (upper leg bone) length of 1.22 meters, compared to 0.74 meter femur of the holotype.[4]
Deltadromeus skeletons have been found in the same formations as those of the giant theropods Carcharodontosaurus, Spinosaurus, and Bahariasaurus, which may be synonymous with Deltadromeus. No skull material has been found for either Deltadromeus or Bahariasaurus, and though carnivore teeth labelled as "Deltadromeus" are commonly sold in rock shops, there is no way of knowing if they actually come from this animal.[1]
Deltadromeus is thought to have weighted up to 2 metric tons.
Classification[]
Deltadromeus was originally described as a large coelurosaur, but more recent studies suggest it was actually a ceratosaur, though exactly what type of ceratosaur remains unknown. One 2003 study suggested it was a member of the Noasauridae,[6] though others have found it to be more primitive, possibly related to the primitive ceratosaurs Elaphrosaurus and Limusaurus. However more recent studies showed it was a Carnosauria since Gualicho was a Sister taxa to Deltadromeus which was possibly the same animal as Aoniraptor.
The cladogram below follows a 2016 analysis by Oliver Rauhut, and Matthew Carrano.
| Abelisauroidea |
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Different analyses have not found Deltadromeus to be a ceratosaur. An analysis of Gualicho, a South American theropod belonging to the allosauroid family Neovenatoridae, finds Deltadromeus to be Gualicho's probable sister taxon.[1] In an analysis of Aoniraptor, which may be the same animal as Gualicho, Deltadromeus was found along with Aoniraptor and Bahariasaurus to probably form a still poorly known clade of megaraptoran tyrannosauroids different from the Megaraptoridae.[2]
The cladogram below follows a 2016 analysis by Sebastián Apesteguía, Nathan D. Smith, Rubén Juarez Valieri, and Peter J. Makovicky.[1]
| Allosauroidea |
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References[]
- ^ a b Sebastián Apesteguía; Nathan D. Smith; Rubén Juárez Valieri; Peter J. Makovicky (2016). "An Unusual New Theropod with a Didactyl Manus from the Upper Cretaceous of Patagonia, Argentina". PLoS ONE 11 (7): e0157793. doi:.
- ^ Matías J. Motta, Alexis M. Aranciaga Rolando, Sebastián Rozadilla, Federico E. Agnolín, Nicolás R. Chimento, Federico Brissón Egli, and Fernando E. Novas (2016). "New theropod fauna from the Upper Cretaceous (Huincul Formation) of northwestern Patagonia, Argentina". New Mexico Museum of Natural History and Science Bulletin 71: 231–253.