Showing papers on "Avialae published in 2007"
TL;DR: A dinosaur from Mongolia represents the basal divergence within Dromaeosauridae and its small body size and phylogenetic position imply that extreme miniaturization was ancestral for Paraves as discussed by the authors.
Abstract: Fossil evidence for changes in dinosaurs near the lineage leading to birds and the origin of flight has been sparse. A dinosaur from Mongolia represents the basal divergence within Dromaeosauridae. The taxon's small body size and phylogenetic position imply that extreme miniaturization was ancestral for Paraves (the clade including Avialae, Troodontidae, and Dromaeosauridae), phylogenetically earlier than where flight evolution is strongly inferred. In contrast to the sustained small body sizes among avialans throughout the Cretaceous Period, the two dinosaurian lineages most closely related to birds, dromaeosaurids and troodontids, underwent four independent events of gigantism, and in some lineages size increased by nearly three orders of magnitude. Thus, change in theropod body size leading to flight's origin was not unidirectional.
308 citations
TL;DR: The analysis results in wide phylogenetic separation between Caenagnathus (close to the base of Oviraptorosauria) and Chirostenotes (placed within a clade of crested oviraptorids), casting doubt on their synonymy.
Abstract: Synopsis The most comprehensive phylogenetic analysis of the theropod clade Coelurosauria to date, is presented here, with 85 coelurosaurian ingroups and 360 characters, using Allosaurus and Sinraptoras outgroups. The strict consensus tree is highly resolved and has the following topology: Tyrannosauroidea + (Compsognathidae + (Arctometatarsalia + (Ornitholestes + (Therizinosauroidea + (Alvarezsauridae + (Oviraptorosauria + (Avialae + (Troodontidae + Dromaeosauridae)))))))). The analysis places Coelurus and Tanycolagreus at the base of Tyrannosauroidea, Deinocheirus within Arctometatarsalia, Protarchaeopteryx within Oviraptorosauria and Epidendrosaurus at the base of Avialae. The analysis results in wide phylogenetic separation between Caenagnathus (close to the base of Oviraptorosauria) and Chirostenotes (placed within a clade of crested oviraptorids), casting doubt on their synonymy. All taxa with an enlarged, trenchant ungual on the second toe are placed within Troodontidae or Dromaeosauridae; at the b...