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RE: some questions



> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> David Carrizosa
>
> 1.- I don't have the paper 'bout Rajasaurus, but in the abstract
> that Nicolas Gardner
> put in the list 'bout 2 or 3 months ago, i read that they found
> Rajasaurus to be closer
> to Majungatholus and Carnotaurus, so here it's my question, i was
> drawing the skull of
> Rajasaurus based on NG photos and it looks really similar to
> Abelisaurus,i think closer
> than Majungatholus or Carnotaurus, and also resemble some figures
> that i found while ago
> of Indosuchus, Does someone can explain me why they put it closer
> to Majungatholus and Carnotaurus.

The details of the phylogenetic position of Rajasaurus haven't been fully
published yet, but word has it that they are on their way.  Just want to
point out, though, that similarity to Abelisaurus are *shared primitive
traits*, not shared derived ones. One can be more similar in a general sense
to some other form because of primitive features, but still be more closely
related to a specialized derived form. For example, our hands and opposum
hands both have five fingers, but horses only have one.  However, we are
more closely related to horses (both placental mammals).

> 2. If the new Nanotyrannus especimen proves that's not a
> juvenile, Alioramus would still de
> considered a juvenile tyrannosaurid.

Two issues:
1) The Nanotyrannus specimen is almost certainly a juvenile. That is a
different issue from whether it is distinct from Tyrannosaurus rex.
2) Alioramus does also show features of unquestioned juvenile tyrannosaurid
specimens, but a complete revision of this specimen is needed for a more
complete answer.

> 3. There are some theories that said that Tarbosaurus &
> Tyrannosaurus emerged without any contact
> so that they developed in similar way in different places, Does
> anyone have ever tried to
> separate Saurolophus Osborni from Saurolophus Angustirostris,
> cause be a similar case, i think.

George Olshevsky has proposed that on this list.  To my knowledge no
hadrosaur worker has followed up in this.

(Incidentally, I personally don't buy a deep separation between Tarbosaurus
and Tyrannosaurus; at worst you would have Daspletosaurus closer to one or
the other, but all these three are very similar compared to Gorgosaurus and
Albertosaurus).

                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