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Re: Question on Anchiornis huxleyi



NOTE: I had said, and Tim followed, by saying they had the MORPHOTYPE of
the ancestor. This is entirely different from saying "were the populations
from which X is directly derived", i.e., actual ancestors.

There are minor differences between them, yes, but all share a number of
generalized paravian traits in common at the same body size.

On Mon, June 24, 2013 10:54 pm, Mark Pauline wrote:
Of course no one is suggesting that Aurornis, Anchiornis, or Xiaotingia are
ancestral to Avialae or Dromaeosauridae, as all of the recent phylogenies
I am aware
of show these animals evolving after those nodes. You two must just mean
that they
may retain different aspects of that hypothetical ancestor.




________________________________
 From: Tim Williams <tijawi@gmail.com>
To: dinosaur@usc.edu
Sent: Monday, June 24, 2013 8:18 PM
Subject: Re: Question on Anchiornis huxleyi


Thomas R. Holtz, Jr. <tholtz@umd.edu> wrote:

> 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.


I couldn't agree more.  Alas, while the morphotype of this
dromaeosaurid/bird ancestor is being nailed down, the ecotype is still
open to vigorous debate.  Was this ancestral form terrestrial or
arboreal?  Did  fly, or not fly?  Was it a predator, or a herbivore,
or both (omnivore)?



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