[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

RE: Pterosaur origins




The same volume also includes a revised phylogeny of coelurosaurs by Phil Senter. The phylogeny contains a few surprises (or maybe not, in some cases)...


_Coelurus_ and _Tanycolagreus_ form a clade (Coeluridae) at the base of the Tyrannosauroidea. (No mention of _Stokesosaurus_.)

_Deinocheirus_ is found to be a basal ornithomimosaur ("arctometatarsalian" in Senter's system).

A monophyletic Compsognathidae is recovered, containing _Compsognathus_, _Sinosauropteryx_ and _Huaxiagnathus_.

No support is found for a unique Therizinosauroidea-Oviraptorosauroidea clade (i.e., to the exclusion of deinonychosaurs, birds, and alvarezsaurids).

A unenlagiine clade turns up, which includes _Unenlagia_, _Buitreraptor_ and _Unenlagia_. Unenlaginae comes out at the base of the Dromaeosauridae; but Senter rejects the idea that dromaeosaurids were secondarily flightless. Instead, the traits common to unenlagiines and birds (ornithurans) - and also present in microraptorans too - are interpreted as convergent in all three clades. (I'm not sure what this means for the flight abilities of _Rahonavis_.)

_Epidendrosaurus_ is found to be a bird. Well, it's inside Avialae but outside Aves, which has _Archaeopteryx_+_Wellnhoferia_ as its most basal clade. Senter defines Avialae as "all taxa more closely related to birds than to Deinonychosauria", whereas Aves is defind as "all taxa phylogenetically bracketed by _Archaeopteryx_ and Neornithes". I know neither definitions conform to PhyloCode, since individual species are not used. But I like the spirit behind both definitions, especially Avialae being stem-based (must exclude deinonychosaurs), and Aves being node-based (must include _Archaeopteryx_.


Sener, P. (2007). A new look at the phylogeny of Coelurosauria (Dinosauria: Theropoda). Journal of Systematic Palaeontology. Published online.


Abstract: "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."

_________________________________________________________________
Like the way Microsoft Office Outlook works? You?ll love Windows Live Hotmail. http://imagine-windowslive.com/hotmail/?locale=en-us&ocid=TXT_TAGHM_migration_HM_mini_outlook_0507