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RE: Mesozoic roots of parrots and passerine birds



  To be absolutely clear here, I do not think the present analyses have 
clarified the issue with respect to how far I'd have rather they go. There are, 
as was said earlier, cladistic analyses that may be tested to consider the jaw 
fragment. I've added the jaw in at one point to one large analysis WAY back 
when, but forgot the results; I've asked Mickey to plug the specimen in to some 
analyses, and I think Andrea Cau has plugged the specimen in to his 
mega-matrix. My understanding is that it comes out as a bird in virtually all 
results, and constraining it to a caenagnathid does increase the quality of the 
analysis otherwise, or at least pushes parsimony around by increasing the steps 
and decreasing posterior probability.

  As a biomechanically-inclined individual, however, phylogenetics is not the 
way I'd prefer to interpret the fossil initially, but rather by seeing whether 
extreme small size (the resulting animal would be smaller than *Caenagnathasia 
martinsoni*) will result in different jaw morphology in a related animal. If it 
is a super-dwarf caenagnathid, we may be seeing features that are related 
merely to that dwarfism. It may also be convergent on the conditions of 
caenagnathids and some particular avians, but be neither. It wouldn't even 
matter if it came from younger than the Lance and was somehow reworked into the 
Mesozoic as this should not influence its morphology or phylogeny.

  Without more of the material, it may be effectively impossible to resolve the 
quandary. Perhaps with better results in modern phylogenetic analyses, sure, 
but I do not think they are the most appropriate tool. As it stands, I have no 
specific reason to reject an avialaean relationship, and no reason to 
reasonably support an oviraptorosaurian one.

Cheers,

  Jaime A. Headden
  The Bite Stuff (site v2)
  http://qilong.wordpress.com/

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)


"Ever since man first left his cave and met a stranger with a
different language and a new way of looking at things, the human race
has had a dream: to kill him, so we don't have to learn his language or
his new way of looking at things." --- Zapp Brannigan (Beast With a Billion 
Backs)


----------------------------------------
> Date: Sat, 27 Aug 2011 17:05:58 -0300
> Subject: Re: Mesozoic roots of parrots and passerine birds
> From: augustoharo@gmail.com
> To: qi_leong@hotmail.com
> CC: dinosaur@usc.edu
>
> 2011/8/27 Jaime Headden <qi_leong@hotmail.com>:
> >
> >   ...Dyke and Mayr have argued, does not resemble that of Paleogene or 
> > Neogene psittaciform fossils.
>
> Of course not doubting of the huge knowledge both Mayr and Dyke have
> regarding paleontology of modern birds, but it seems to me a weak
> argument to claim that a cretaceous parrot should be more similar to
> Paleogene birds than to Recent ones. For it is so common in the fossil
> record that generally more plesiomorphic (and thus basal) specimens
> appear later in time than early generally more apomorphic ones.
>
> >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.
>
> Thanks for the further clarification and elaboration. But although
> Dyke and Mayr (1999) stated that the vascular K-like mark was present
> in other birds, I was not able to find in their comment, or in your
> review, evidence that non-avialan theropods present that vascular
> trait stated by Stidham. So, in my opinion, although these are few
> features (few arguments) on the basis of which to allocate the
> specimen, I think that Stidham's still seems to be the most
> parsimonious inference on the basis of the analyzed anatomical
> features of the specimen, unless there is a further study I do not
> know nothing of stating otherwise.
>
> Of course, a phylogenetic analysis including the material should be
> better than this opinion, for there is the possibility that because of
> being so incomplete and thus full of missing data, the material jumps
> between several alternative positions, weakening the allocation by
> Stidham.
>
> The only argument it seems to me there currently is against Stidham's
> systematic allocation is a stratigraphic one, and in my opinion these
> arguments are weak, as systematics are based on anatomy and not
> bichrons.
>
> Of course one may still be wrong if following Stidham's systematic
> judgement, as in the case of the Revueltosaurus teeth, but it may be
> said that at the moment Revueltosaurus' teeth were first recovered,
> considering them ornithischians was the best guess possible, if the
> teeth shared more apomorphies with then known ornithischians instead
> of then known crurotarsans.
>
> Cheers,
> Augusto
> >
> > Cheers,
> >
> >  Jaime A. Headden
> >  The Bite Stuff (site v2)
> >  http://qilong.wordpress.com/
> >
> > "Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)
> >
> >
> > "Ever since man first left his cave and met a stranger with a
> > different language and a new way of looking at things, the human race
> > has had a dream: to kill him, so we don't have to learn his language or
> > his new way of looking at things." --- Zapp Brannigan (Beast With a Billion 
> > Backs)
> >
> >
> > ----------------------------------------
> >> Date: Fri, 26 Aug 2011 20:05:17 -0300
> >> From: augustoharo@gmail.com
> >> To: dinosaur@usc.edu
> >> Subject: Re: Mesozoic roots of parrots and passerine birds
> >>
> >> Changing a little the axis of the discussion, was it proved that
> >> pretended Cretaceous parrot (Stydham, 1998, in Nature) was actually
> >> not a parrot? Dyke and Mayr's 1999 reponse stated it may be a
> >> non-avian theropod, but I was not able to find refutation (it may be
> >> said that because of being Cretaceous, the burden of proof is on
> >> proving it is a parrot, but the best test would consist in including
> >> the specimen in a data matrix of maniraptorans).
> >>
> >> Cheers,
> >>
> >> Augusto
> >