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Re: new dinosaurs



One potential problem with the JVP analysis of _Appalachiosaurus_ - the
characters used are restricted to those present in the hypodigm of _Appa._,
except for a single character that had to be included to retain
_Albertosaurus_ as monophyletic. I always grind my teeth somewhat when I see
this approach - we're all aware of the dangers of small character sets, and
deliberately leaving characters out...
    Few things can cause more trouble than getting a resulting tree that is
well-resolved, strongly supported and WRONG!

    Ka kite,

        Christopher Taylor

On 30/3/05 5:14 am, "Thomas R. Holtz, Jr." <tholtz@geol.umd.edu> wrote:

>> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
>> Tim Williams
>> 
>> I wrote:
>> 
>>> I have not yet seen the JVP paper (though I would dearly love to), but the
>>> cladogram in _Dinosauria II_ shows that _Appalachiosaurus_ and
>>> _Dryptosaurus_ come up in different parts of the Tyrannosauroidea tree. The
>>> "Alabama taxon" (= _Appalachiosaurus_) belongs on the
>>> _Albertosaurus_-_Gorgosaurus_ line of the Tyrannosauridae, whereas
>>> _Dryptosaurus_ is given as a basal tyrannosauroid. Any similarities between
>>> the two are presumably symplesiomorphic.
>> 
>> Scratch that.  According to the JVP paper, both _Dryptosaurus_ and
>> _Appalachosaurus_ are basal tyrannosauroids - though certainly distinct.
>> 
> 
> Just wanted to add that putting Dilong into my matrix pulled Appalachiosaurus
> out of Albertosaurinae, and Tyrannosauridae, and put
> it in the position that Carr et al. found.
> 
> That being said, the Albertosaurinae characters listed in DinoII are indeed
> present in Appa., so a return to that position is not
> out of the question.
> 
> Thomas R. Holtz, Jr.
> Vertebrate Paleontologist
> Department of Geology        Director, Earth, Life & Time Program
> University of Maryland        College Park Scholars
> Mailing Address:
> Building 237, Room 1117
> College Park, MD  20742
> 
> http://www.geol.umd.edu/~tholtz/
> 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
> 
>