Deltadromeus

Deltadromeus Temporal range: Late Cretaceous, 95 Ma PreЄ Є O S D C P T J K Pg N ↓
Mounted skeleton cast with reconstructed skull, Montshire Museum
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Superorder:	Dinosauria
Order:	Saurischia
Suborder:	Theropoda
Infraorder:	Ceratosauria
Genus:	Deltadromeus Sereno et al., 1996
Species
D. agilis Sereno, 1996 (type)

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 late Cretaceous Period (mid Cenomanian age), about 95 million years ago. It may be a junior synonym of the contemporary Bahariasaurus.^[1]

Description

Life restoration

The fairly complete holotype skeleton of Deltadromeus agilis (museum catalogue number SGM-Din2) measured an estimated 8 m (26.2 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]

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,^[5] though others have found it to be more primitive, possibly related to the primitive ceratosaurs Elaphrosaurus and Limusaurus.^[6][7]

References

1. ^ ^{a b} Holtz, Thomas R. Jr. (2008) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages Supplementary Information
2. ^ Seebacher, F. (2001). "A new method to calculate allometric length-mass relationships of dinosaurs." Journal of Vertebrate Paleontology, 21(1): 51–60.
3. ^ Stromer (1934). "Ergebnisse der Forschungsreisen Prof. E. Stromers in den Wüsten Ägyptens." II. Wirbeltierreste der Baharije-Stufe (unterstes Cenoman). 13. Dinosauria. Abh. Bayer. Akad. Wiss., Math.-Nat. Abt., (n. s.) 22 1-79, 3 pls.
4. ^ ^{a b} Sereno, Dutheil, Iarochene, Larsson, Lyon, Magwene, [[Sidor (C.A.)}]], Varricchio and Wilson (1996). "Predatory Dinosaurs from the Sahara and Late Cretaceous Faunal Differentiation." Science, 272(5264): 986-991.
5. ^ Wilson, Sereno, Srivastava, Bhatt, Khosla and Sahni. (2003). "A new abelisaurid (Dinosauria, Theropoda) from the Lameta Formation (Cretaceous, Maastrichtian) of India." Contr. Mus. Palaeont. Univ. Mich., 31: 1-42.
6. ^ Carrano & Sampson (2008). "The Phylogeny of Ceratosauria (Dinosauria: Theropoda)". JSysPaleo 6: 183-236
7. ^ Xu, X., Clark, J.M., Mo, J., Choiniere, J., Forster, C.A., Erickson, G.M., Hone, D.W.E., Sullivan, C., Eberth, D.A., Nesbitt, S., Zhao, Q., Hernandez, R., Jia, C.-K., Han, F.-L., and Guo, Y. (2009). "A Jurassic ceratosaur from China helps clarify avian digital homologies." Nature, 459(18): 940–944. doi:10.1038/nature08124

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