comments in this week's Science about the Thermopolis Archaeopteryx

["Thomas R. Holtz, Jr." <tholtz@geol.umd.edu>]

Two brief articles in the latest Science (actually, a Technical Comment and 
Response) about the Mayr et al. article on the
Thermopolis Archaeopteryx:

Corfe, I.J. & R.J. Butler. 2006. Technical Comments: Comment on "A 
Well-Preserved Archaeopteryx Specimen with Theropod Features".
Science 313:1238.

Abstract
On the basis of new information from the 10th specimen of Archaeopteryx, Mayr 
et al. (Reports, 2 December 2005, p. 1483) suggested
that birds, or avian flight, originated twice. We investigate the statistical 
support for this phylogenetic hypothesis and show that
it is no better supported by available morphological character data than the 
hypothesis of a single avian origin.

and the response:
Mayr, G., and D.S. Peters. 2006. Response to Comment on "A Well-Preserved 
Archaeopteryx Specimen with Theropod Features". Science
313:1238.

Abstract
We agree that statistical support for our proposed phylogeny is weak, but the 
monophyly of Aves favored by most current researchers
is also weakly supported. In the absence of unambiguous apomorphies of a clade 
including Archaeopteryx and Confuciusornis but not
deinonychosaurs, we do not believe that the statistical comparisons made by 
Corfe and Butler challenge our hypothesis regarding the
ancestry of birds.

Basic thread from both of these: there is "little current consensus as to the 
relationships between Archaeopteryx, Rahonavis, and
Confuciusornis within Coelurosauria" (Corfe & Butler) and that the features of 
the Mayr et al. phylogeny are poorly supported "but
this is also true for the competing hypothesis favored by most current 
researchers, that is, monophyly of a group including
Archaeopteryx and pygostylians and excluding deinonychosaurs." (Mayr & Peters).

Mayr & Peters explictly support elements of Greg Paul's Secondary 
Flightlessness hypothesis: "Corfe and Butler incorrectly state
that we suggested "birds, or avian flight, originated twice." We do not assume 
that flight was gained independently more than once
within theropods but consider it more likely that flight ability was lost 
several times independently in the clade including
Archaeopteryx, deinonychosaurs, and pygostylians (7). This is a reasonable 
assumption irrespective of the position of Archaeopteryx,
because the presence of modern-type wing feathers in the dromaeosaur 
Microraptor (8) alone suggests secondary loss of flight ability
in the larger species of Deinonychosauria.".

                Thomas R. Holtz, Jr.
        Senior Lecturer, Vertebrate Paleontology
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/
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