A new look at the phylogeny of Coelurosauria (Dinosauria: Theropoda)

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 Sinraptor as 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 base of the latter is an unenlagiine clade that includes Unenlagia and Rahonavis. The hypothesis that dromaeosaurids are secondarily flightless birds is not supported.