Dinosauriformes

Dinosauriformes Temporal range: Middle Triassic - Recent, 245–0 Ma PreЄ Є O S D C P T J K Pg N
Mounted skeleton of Marasuchus, an early dinosauriform
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Branch:	Dinosauromorpha
Branch:	Dinosauriformes Novas, 1992
Clades
Dinosauria †Marasuchus †Pseudolagosuchus †Saltopus †Silesauridae

Dinosauriformes is a clade of archosaurian reptiles that include the dinosaurs and their most immediate relatives. All dinosauriformes are distinguished by several features, such as shortened forelimbs, and an at least partially perforated acetabulum, the hole in the hip socket traditionally used to define dinosaurs. The oldest known member is Asilisaurus, dating to about 245 million years ago in the Anisian age of the middle Triassic period.^[1]

The term Dinosauriformes was coined and defined in 1992 by F.E. Novas, who used it to include the herrerasaurs, which he did not consider members of Dinosauria proper. Contrary to Novas, most paleontologists since 1992 have considered herrerasaurs to be true dinosaurs, though many other primitive, dinosaur-like reptiles fall within his definition of Dinosauriformes. Dinosauriformes fall within the clade Dinosauromorpha.

Phylogeny

Cladogram simplified after Nesbitt (2011):

Dinosauriformes	Marasuchus unnamed Silesauridae Dinosauria Ornithischia Saurischia Sauropodomorpha Theropoda

References

1. ^ Nesbitt, S.J.; Sidor, C.A.; Irmis, R.B.; Angielczyk, K.D.; Smith, R.M.H.; and Tsuji, L.M.A. (2010). "Ecologically distinct dinosaurian sister group shows early diversification of Ornithodira". Nature 464 (7285): 95–98. doi:10.1038/nature08718. PMID 20203608. 

• Ezcurra, M.D. (2006). A review of the systematic position of the dinosauriform archosaur Eucoelophysis baldwini Sullivan & Lucas, 1999 from the Upper Triassic of New Mexico, USA. Geodiversitas, 28 (4): 649-684.
• Hutchinson, J.R. & Gatesy, S.M. (2000). Adductors, abductors, and the evolution of archosaur locomotion. Paleobiology 26 (4): 734-751
• Novas, F.E. (1996). Dinosaur Monophyly. Journal of Vertebrate Paleontology 16 (4): 723-741.
• Sereno, P.C. and Arcucci, A.B. (1994). Dinosaur precursors from the Middle Triassic of Argentina: Lagerpeton chanarensis. Journal of Vertebrate Paleontology 13: 385-399.

External links

• PaleoWiki Information on Taxon Dinosauromorpha
• Info on Dinosauromorpha from Paleontological Database
• Info on Dinosauromorphs from Thelescosaurus!