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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
Author(s): Alan H. Turner, Peter J. Makovicky, and Mark A. NorellSource:
Bulletin of the American Museum of Natural History, Number
Published By: American Museum of Natural History
Senior Principal Preparator
American Museum of Natural History
(212) 496 3544
On 6/20/13 8:32 AM, "Thomas R. Holtz, Jr." <firstname.lastname@example.org> 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; email@example.com
>> 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
>> (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: firstname.lastname@example.org Phone: 301-405-4084
>Office: Centreville 1216
>Senior Lecturer, Vertebrate Paleontology
>Dept. of Geology, University of Maryland
>Faculty Director, Science & Global Change Program, College Park Scholars
>Mailing Address: Thomas R. Holtz, Jr.
> Department of Geology
> Building 237, Room 1117
> University of Maryland
> College Park, MD 20742 USA