Gaia theropod follow-up: a "new" phylogeny

["Thomas R. Holtz, Jr." <tholtz@geol.umd.edu>]

Howdy,

Just thought I'd give a little more detail on the new phylogeny paper in the
Gaia volume.  The ref is:
Holtz, T.R., Jr. 2000. A new phylogeny of the carnivorous dinosaurs. Gaia
15: 5-61.

Okay, 41 ingroup taxa (plus 3 fragmentary specimens held in reserve, each
added independantly) and 386 characters, run with either Herrerasauridae,
basal Sauropodomorpha, or an allzero outgroup as sister taxa.

Results:
20 equally most parsimonious trees, with the following topology (+ means an
operational taxonomic unit in the study):
Neotheropoda
  Ceratosauria
    Coelophyosoidea
      Coelophysidae+
      _Dilophosaurus_+
    Neoceratosauria
      _Elaphrosaurus_+ (although 1 step out and it can be the sister to
Coelophysoidea or the sister to Coelophysidae)
      unnamed
        _Ceratosaurus_+
        Abelisauridae
          _Carnotaurus_+
          _Abelisaurus_+
  Tetanurae
    Spinosauridae+
    unnamed
      _Megalosaurus bucklandi_+
      unnamed
        _Eustreptospondylus_+
        unnamed
          _Torvosaurus_+
          unnamed
            _Piatnitzkysaurus_+
            unnamed
              _Afrovenator_+
              Avetheropoda
                Carnosauria
                  _Monolophosaurus_+
                  Allosauroidea
                          Sinraptoridae
                      _Sinraptor_+
                      _Yangchuanosaurus_+
                    Allosauridae
                      unnamed ("allosaurines")
                        _Allosaurus_+
                        _Neovenator_+
                      unnamed ("carcharodontosaurines")
                        _Acrocanthosaurus_+
                        unnamed
                          _Giganotosaurus_+
                          _Carcharodontosaurus_+
                Coelurosauria
                  _Proceratosaurus_+ (also fits between _Gaso._ & _Drypto._,
and closer to _Ornithol._ and above than to _Drypto._)
                  _Gasosaurus_+
                  unnamed
                    _Dryptosaurus_+
                    unnamed
                      _Ornitholestes_+
                      unnamed
                        _Coelurus_+
                        unnamed
                          _Scipionyx_+
                          unnamed
                            _Bagaraatan_+
                            Maniraptoriformes
                              Arctometatarsalia
                                Tyrannosauridae+
                                (Bullatosauria
                                   Troodontidae+, position 1)
                                   Ornithomimosauria
                                     _Pelecanimimus_+
                                     Ornithomimidae+
                              Maniraptora
                                Compsognathidae+
                                unnamed
                                  unnamed ("enigmosaurs")
                                    Therizinosauroidea+
                                    Oviraptorosauria
                                      _Microvenator_+
                                      Caenagnathidae+
                                      Oviraptoridae+
                                  (Paraves
                                    Troodontidae+, position 2)
                                    Eumaniraptora
                                                  Dromaeosauridae+
                                      Avialae
                                        _Rahonavis_+
                                        Aves
                                          _Archaeopteryx_+
                                          Metornithes
                                            Alvarezsauridae+
                                            Ornithothoraces+

Of the three taxa held in reserve, as it were: _"Megalosaurus" hesperis_
fits in lots of positions in the non-avetheropod tetanurines; _Deltadromeus_
in various positions among the basal coelurosaurs or basal maniraptorans;
and _Unenlagia_ among the basal avialians.

_Caudipteryx_, _Protarchaeopteryx_, and Confusciusornithidae were not
included in this study: they are added in part II of this study, in the
Ostrom Symposium volume.

As you can see, troodontids wind up being EITHER the sister group to
ornithomimosaurs OR the sister group to eumaniraptorans.  And, to make
matters worse, in one step out they become the sister taxon to the
oviraptorosaur-therizinosauroid clade!

However, at SVP I will be tearing much of the above structure apart, and
presenting a whole new, even more detailed (URGH) phylogenetic analysis of
the theropods.

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
http://www.geol.umd.edu/~tholtz/tholtz.htm
http://www.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796