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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
_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
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
_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."
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