Unenlagiidae is a proposed family ofeumaniraptoran paravians that includes the subfamiliesUnenlagiinae and possiblyHalszkaraptorinae. Fossils of both subfamilies have been found in bothGondwanan andLaurasian deposits. The biology of the group suggests that some members were semiaquatic specialists.[1]
The family Unenlagiidae traditionally includes the same members as the previously named subfamily ofDromaeosauridae,Unenlagiinae, so Unenlagiidae was often seen as a synonym of Dromaeosauridae. However, since the 2010s, there have been subsequent studies that have questioned this placement, necessitating the revival of the family name. Some have placed unenlagiids as outside Dromaeosauridae, being the sister taxon or closely related toAvialae,[2][3] while others have placed the newly recognizedhalszkaraptorines in the family, as basaldeinonychosaurs outside Dromaeosauridae andTroodontidae.[4] Other recent studies supported the traditional placement of Halszkaraptorinae and Unenlagiinae in Dromaeosauridae, forming no distinct clade.[1][5] In 2021, Brum et al. named the cladeUnenlagiinia for a unifiedUnenlagia+Halszkaraptor clade, recovering them as basal dromaeosaurs.[6]
The following cladogram is from Motta et al., 2020, showing Unenlagiidae outside dromaeosaurids and more closely related to Avialae:[3]
^abCau, A.; Beyrand, V.; Voeten, D.; Fernandez, V.; Tafforeau, P.; Stein, K.; Barsbold, R.; Tsogtbaatar, K.; Currie, P.; Godrfroit, P. (6 December 2017). "Synchrotron scanning reveals amphibious ecomorphology in a new clade of bird-like dinosaurs".Nature.552 (7685):395–399.Bibcode:2017Natur.552..395C.doi:10.1038/nature24679.PMID29211712.S2CID4471941.
^Federico L. Agnolín and Fernando E. Novas (2013).Avian ancestors. A review of the phylogenetic relationships of the theropods Unenlagiidae, Microraptoria,Anchiornis and Scansoriopterygidae. SpringerBriefs in Earth System Sciences. pp. 1–96.doi:10.1007/978-94-007-5637-3.ISBN978-94-007-5636-6.S2CID199493087.
^Brum, Arthur S.; Pêgas, Rodrigo V.; Bandeira, Kamila L.N.; Souza, Lucy G.; Campos, Diogenes A.; Kellner, Alexander W.A. (2021). "A new Unenlagiinae (Theropoda: Dromaeosauridae) from the Late Cretaceous of Brazil".Papers in Palaeontology.7 (4):2075–2099.doi:10.1002/spp2.1375.S2CID238854675.
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