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Dinosauromorpha is the name of a clade of archosaurs that includes the direct sister groups of dinosaurs, and the order Dinosauria itself. Basal forms include Marasuchus, the perhaps identical Lagosuchus, and Lagerpeton from the Ladinian of Argentina, Dromomeron from the Norian of Arizona, New Mexico, and Texas, and "silesaurs", which include Silesaurus from the Carnian of Poland, Eucoelophysis from the Carnian-Norian of New Mexico, Pseudolagosuchus from the Ladinian of Argentina,[1] and potentially Sacisaurus from the Norian of Brazil,[2] and Technosaurus from the Carnian of Texas.[3] Birds are the only surviving dinosauromorphs.
The name was coined by Michael J. Benton in 1984. The first clade definitions were by Paul Sereno in 1991 who accidentally defined the concept as both a node clade: the last common ancestor of Lagerpeton chanarensis, Lagosuchus talampayensis, Pseudolagosuchus major and the Dinosauria (including Aves) and all its descendants, and a stem clade: those Ornithodira more closely related to Dinosauria than to Pterosauria. As a stem clade definition was more functional[citation needed], considering that only few basal Dinosauromorpha are known, and the relationship with Pterosauria is growing ever more problematic, a more specific definition was given by Sereno in 2005: the group consisting of Passer domesticus (Linnaeus 1758) and all species closer to Passer than to Pterodactylus antiquus (Soemmerring 1812), Ornithosuchus woodwardi (Newton 1894) and Crocodylus niloticus (Laurenti 1768). Should the pterosaurs not be closely related to the dinosaurs, this new definition would still be relevant, defining also the relation to the Crurotarsi; in that case it would be an older synonym of Avemetatarsalia.
[edit] References
- ^ Irmis, Randall B.; Nesbitt, Sterling J.; Padian, Kevin; Smith, Nathan D.; Turner, Alan H.; Woody, Daniel; and Downs, Alex (2007). "A Late Triassic dinosauromorph assemblage from New Mexico and the rise of dinosaurs". Science 317: 358–361. doi:10.1126/science.1143325. PMID 17641198.
- ^ Ferigolo, J.; and Langer, M.C. (2006). "A Late Triassic dinosauriform from south Brazil and the origin of the ornithischian predentary bone". Historical Biology 19 (1): 1–11.
- ^ Nesbitt, Sterling J.; Irmis, Randall B.; and Parker, William G. (2007). "A critical re-evaluation of the Late Triassic dinosaur taxa of North America". Journal of Systematic Palaeontology 5 (2): 209–243. doi:10.1017/S1477201907002040.
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