Re: The new Archaeopteryx from... Wyoming?

[Phil Bigelow <bigelowp@juno.com>]

Another article:

http://www.usatoday.com/tech/science/discoveries/2005-12-01-dino-fossil_x
.htm

Its amazing how many mass media outlets simply clone a pool report.

<pb>
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On Thu, 01 Dec 2005 15:44:17 -0600 Tim Williams
<twilliams_alpha@hotmail.com> writes:
> 
> Frank Bliss wrote:
> 
> >As I have always said, material from private collectors eventually 
> make it 
> >into museum's hands.
> 
> Let's hope you are always right.  In the case of this specimen, it 
> is only 
> through the good graces of the owner that it was given over to a 
> museum.
> 
> >From Jeff Hecht's article: "A complete foot reveals that 
> archaeopteryx had 
> an extensible claw on its second toe, which is a hallmark of 
> raptors, but is 
> absent in all known birds. Its first toe, or "hallux", is also at 
> the side 
> of the foot and not reversed as it is in perching birds, which use 
> it to 
> grasp branches."
> 
> It looks like both Greg Paul and Kevin Middleton have some 
> compelling 
> support for their respective interpretations of the _Archaeopteryx_ 
> foot: 
> the second toe has a hyperextensible ungual, and the hallux is not 
> opposable.  I'd have bet my life savings on the latter; but I never 
> found 
> GSP's interpretation of the second toe convincing - until now.
> 
> Anyway, here's the Abstract:
> 
> Gerald Mayr, Burkhard Pohl, and Stefan Peters (2005).  A 
> Well-Preserved 
> _Archaeopteryx_ Specimen with Theropod Features.  Science 310: 
> 1483-1486.
> 
> Abstract: "A nearly complete skeleton of _Archaeopteryx_ with 
> excellent bone 
> preservation shows that the osteology of the urvogel is similar to 
> that of 
> nonavian theropod dinosaurs.  The new specimen confirms the presence 
> of a 
> hyperextendible second toe as in dromaeosaurs and troodontids.  
> _Archaeopteryx_ had a plesiomorphic tetraradiate palatine bone and 
> no fully 
> reversed first toe.  These observations provide further evidence for 
> the 
> theropod ancestry of birds.  In addition, the presence of a 
> hyperextendible 
> second toe blurs the distinction of archaeopterygids from basal 
> deinonychosaurs (troodontids and dromaeosaurs) and challenges the 
> monophyly 
> of Aves."
> 
> Hmmm... I'm not sure it challenges the *monophyly* of Aves, given 
> that 
> Aves/Avialae is defined as a clade, and so must be monophyletic.  It 
> may 
> change the composition of Avialae/Aves, however - but that's no 
> biggie.  A 
> lot of folks have been expecting deinonychosaurs to one day fall 
> inside the 
> Avialae clade.
> 
> The phylogenetic tree has an _Archaeoptery_+_Rahonavis_ clade as 
> sister 
> taxon to a clade comprising deinonychosaurs and _Confuciusornis_ 
> (with 
> dromaeosaurs closer to _Confuciusornis_ than troodontoids).  In 
> fact, 
> _Microraptor_ and _Confuciusornis_ are recovered as sister taxa!  As 
> 
> mentioned in Jeff's New Scientist article (and no doubt Mickey M. 
> would 
> agree) the analysis probably needs to be fleshed out with more 
> birds.  The 
> article actually concedes this: "Although this particular result may 
> be due 
> to the limited sampling of avian taxa...".
> 
> Cheers
> 
> Tim
> 
> 
> 
> 


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