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Re: Question on Anchiornis huxleyi



Dr. Holtz is totally right, of course.

But to answer your questions directly, (1) Turner et al. (2012) found that
Anchiornis (along with Xiaotingia) is a basal troodontid. (2) Further from
Aves than Archaeopteryx. (3) This is using the Theropod Working Group
matrix, which has had a comparatively stable topology in recent years, but
does not yet incorporate Eosinopteryx or Aurornis. It surely will soon.

A Review of Dromaeosaurid Systematics and Paravian
Phylogeny 
Author(s): Alan H. Turner, Peter J. Makovicky, and Mark A. NorellSource:
Bulletin of the American Museum of Natural History, Number
371:1-206. 2012.
Published By: American Museum of Natural History
DOI: http://dx.doi.org/10.1206/748.1
URL: http://www.bioone.org/doi/full/10.1206/748.1





Jason Brougham
Senior Principal Preparator
American Museum of Natural History
jaseb@amnh.org
(212) 496 3544





On 6/20/13 8:32 AM, "Thomas R. Holtz, Jr." <tholtz@umd.edu> wrote:

>> From: owner-VRTPALEO@usc.edu [mailto:owner-VRTPALEO@usc.edu] On Behalf
>>Of Leo W Sham
>> Sent: Thursday, June 20, 2013 2:23 AM
>> To: VRTPALEO@usc.edu; dinosaur@usc.edu
>> Subject: Question on Anchiornis huxleyi
>> 
>> Dear Listers,
>> I am confused about the current taxonomic status of Anchiornis. What is
>>the current opinion for the questions below?
>> 
>> (1) Is it considered a sister taxon/outgroup of Troodontidae, or that
>>of Avialae, or still something else e.g. basal Avialae?
>> (2) It it closer than, or less close than, Archaeopteryx to crown Aves
>>(Neornithes)?
>> (3) Any relevant comments?
>> 
>> Thank you very much in advance! You can reply to me in private.
>
>The main takehome messages of recent papers on basal paravians should be:
>1) There is no simple single unassailable resolution of the position of
>"archaeopterygid"-grade theropods, likely because...
>2) Said animals are very close to the divergence between Dromaeosauridae
>(in whatever combination), Troodontidae (ditto), and
>Avialae (ditto again).
>3) And as such they will continue to jump back and forth between the
>basal branches of the clades in question.
>
>But that is okay. And actually is much more informative than a stabilized
>position. Ultimately it is far less significant to resolve
>whether Archaeopteryx &/or Anchiornis &/or Aurornis &/or Xiaotingia &/or
>etc. are basal avialians or basal deinonychosaurs or so
>forth. Instead we should recognize that we have very likely homed in on
>the morphotype which gave rise to both the
>dromaeosaurid-line and the bird-line. Yes, it will be more helpful in the
>end to pick out which ones fit where, but if some of these
>animals are on one branch and others on the other, then we have
>established the basal morphology of Paraves and the form which gave
>rise to both divergent clades.
>
>NOTE: All the above hinges on the standard model of Deinonychosauria and
>"archaeopterygids" being close to crown-group birds than
>are oviraptorosaurs; the alternative model, proposed by various workers,
>is that Oviraptorosauria is closer to crown-group birds and
>that archaeopterygids are just basal deinonychosaurs.
>
>Thomas R. Holtz, Jr.
>Email: tholtz@umd.edu  Phone: 301-405-4084
>Office: Centreville 1216                       
>Senior Lecturer, Vertebrate Paleontology
>Dept. of Geology, University of Maryland
>http://www.geol.umd.edu/~tholtz/
>Fax: 301-314-9661              
>
>Faculty Director, Science & Global Change Program, College Park Scholars
>http://www.geol.umd.edu/sgc
>Fax: 301-314-9843
>
>Mailing Address:       Thomas R. Holtz, Jr.
>                       Department of Geology
>                       Building 237, Room 1117
>                       University of Maryland
>                       College Park, MD 20742 USA
>
>