Re: The new Archaeopteryx from... Wyoming?

[Tim Williams <twilliams_alpha@hotmail.com>]

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