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RE: Mesozoic roots of parrots and passerine birds




--- Jaime Headden <qi_leong@hotmail.com> schrieb am Sa, 27.8.2011:

> Von: Jaime Headden <qi_leong@hotmail.com>
> Betreff: RE: Mesozoic roots of parrots and passerine birds
> An: "Augusto Haro" <augustoharo@gmail.com>, 
> Dinosaur.Mailing.List@listproc.usc.edu
> Datum: Samstag, 27. August, 2011 08:40 Uhr
> 
>   Dyke, Clarke and a few others have effectively argued
> that the material does not resemble any modern psittaciform
> mandible, and as Dyke and Mayr have argued, does not
> resemble that of Paleogene or Neogene psittaciform fossils.
> It is then considerably unlikely to be a parrot. I comment
> futher here: http://qilong.wordpress.com/2011/03/02/a-cretaceous-parrot/
> . It may still be avian, however, and I specifically do not
> take this argument because of a limited level of comparison.
> It is, in any case, psittaco-morphic (having the shape of a
> parrot) but this is a generalization based on the rounded of
> the rostral margin, fusion, and the shape of neurovascular
> canals both within and upon the symphysis.

To add to that, all known Paleogene stem psittaciforms are by no means as 
advanced (one of the most severely under-cited papers, at least regarding the 
present debate - the molecular studies have simply pretended it does not exist, 
or cited and then entirely disregarded it: 
http://www.ingentaconnect.com/content/tandf/ghbi/2006/00000018/00000002/art00012).

In other words, this "gnathos" is a bit too "kainos" to be a good parrot 
candidate ;-)

Note also http://www.jstor.org/pss/1298656

Given that there are (IIRC) still no oviraptorosaurs - let alone 
caenagnath(o)ids - from the Lance, and that the caenagnathid hypodigm is very 
small, a cladistic restudy of the material is definitely very warranted.


Eike

PS: if anyone needs the two papers mentioned, I have them.