By Federico L. Agnolín, Fernando E. Novas (auth.)
Although consensus exists between researchers that birds advanced from coelurosaurian theropods, paleontologists nonetheless debate the id of the gang of coelurosaurians that the majority heavily methods the typical ancestor of birds. The final twenty years witnessed the invention of a big selection of avian-like theropods that has significantly amplified the anatomical disparity between deinonychosaurians, a few of which resemble Archaeopteryx greater than Deinonychus. between those newly chanced on theropods that convey outstanding bird-like features are the four-winged theropods Microraptor and Anchiornis, and the unenlagiids Unenlagia, Buitreraptor, and Rahonavis. A strange team of minute-sized coelurosaurs, the Scansoriopterygidae, additionally indicates a few avian similarities that lead a few authors to interpret them as extra heavily regarding birds than different dinosaurs. With the purpose to discover the phylogenetic relationships of those coelurosaurians and birds, we merged lately released integrative databases, leading to major adjustments within the topological distribution of taxa inside Paraves. We current facts that Dromaeosauridae, Microraptoria, Unenlagiidae, and Anchiornis + Xiaotingia shape successive sister taxa of Aves, and that the Scansoriopterygidae are basal coelurosaurians now not heavily concerning birds. the results within the evolutionary series of anatomical characters resulting in birds, together with the starting place of flight, also are thought of in mild of this new phylogenetic hypothesis.
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Additional info for Avian Ancestors: A Review of the Phylogenetic Relationships of the Theropods Unenlagiidae, Microraptoria, Anchiornis and Scansoriopterygidae
6 Mahakala omnogova 41 et al. 2008; Longrich and Currie 2008), or as the basalmost Dromaeosauridae (Turner et al. 2007a, 2011). Although Mahakala is not included in the present analysis, the phylogenetic position inferred by all those authors implies averaptoran affinities for this taxon. Turner et al. (2007a) recognized many features from which Mahakala differed from other dromaeosaurids, including a broad ulna, reduced cuppedicus fossa on ilium, vaulted braincase, fibula not contacting distal tarsals, and minute size.
2010), that scansoriopterygids are basal maniraptorans which exhibits sister group relationships with Oviraptorosauria. References Agnolín FL, Novas FE (2011) Unenlagiid theropods: are they members of dromaeosauridae (theropoda, maniraptora). An Acad Bras Ciênc 83:117–162 Alonso PD, Milner AC, Ketcham RA, Cokson MJ, Rowe TB (2004) The avian nature of the brain and inner ear of Archaeopteryx. Nature 430:666–669 Barsbold R, Osmólska H (1999) The skull of Velociraptor (Theropoda) from the Late Cretaceous of Mongolia.
Concluding, most (if not all) remains of European dromaeosaurid-like specimens lack derived traits that may unite them with Unenlagiidae among averaptoran theropods. References Agnolín FL, Novas FE (2011) Unenlagiid theropods: are they members of Dromaeosauridae (theropoda, Maniraptora). An Acad Bras Ciênc 83:117–162 Allain R, Taquet P (2000) A new genus of Dromaeosauridae (Dinosauria, Theropoda) from the Upper Cretaceous of France. J Vert Paleont 20:404–407 Averianov AO, Sues HD (2007) A new troodontid (Dinosauria: Theropoda) from the Cenomanian of Uzbekistan, with a review of troodontid records from the territories of the former Soviet Union.