RE: Gaia theropod follow-up: a "new" phylogeny

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

> From: ekaterina amalitzkaya [mailto:eamalitz@hotmail.com]
>
>
> In the phylogenetic tree provided by Thomas R. Holtz Jr. there was no
> Cryolophosaurus. Was this just an accidental ommision or was it
> left out due
> to specific reasons?

Left out because I have not had opportunity to either examine the specimen
first hand nor to see detailed photographs of the specimen.  From some of
the photos I have seen, the oft-repeated line drawing seems to have some
inaccuracies.

However, I do address the temporal significance of the taxon in the
Discussion.

> The early tetanurans according to this
> picture do not
> form any good cluster but simply stack up on the crown group. Does this
> suggest a general lack of specialized innovation in the early
> Gondwanaland?

Not really as such (indeed, evidence for a biogeographically distinct
"Gondwana" during the Early Mesozoic, in terms of dinosaurs, is not
particularly strong).  However, don't put too much weight on the precise
phylogenetic positions of the basal tetanurines as they show up in the
study: the support for nearly all those positions is very weak, and in trees
just one, two, or three steps longer they begin to mix and match.

> How much of this M.bucklandi is known. I remember a dentary that was well
> illustrated in a pamphlet provided by some English museum. Is
> there more to
> this beast.

Yes: there are verts, forelimb material, pelvic material, hindlimb material.

> The same pamphlet also showed a small theropod called
> Altispinax
> and called these large neural spines as coming from some Megalosaurus
> species. Any idea what these neural spines came from?

Well, they came from a taxon now called _Becklespinax_.  However, as for the
phylogenetic position of this taxon: difficult to say at present.

                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