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Re: New papers (relevant to bird origins)



> Two recent papers caught my interest, neither of which I have read (beyond
> the abstract anyway).  My apologies if these have been mentioned
before....

They haven't AFAIK.

> The first is by DML listmember, Renesto Silvio.  It has some interesting
> thoughts on the identity of the skull of _Protoavis_.

[snip]

> Morphology of
> observable skull elements and cervical vertebrae in one of the new
specimens
> shows some resemblance to the possible Triassic bird Protoavis, while the
> postcranial skeleton of Megalancosaurus is completely non-avian. This may
> suggest that either Megalancosaurus and Protoavis developed a similar neck
> structure as a response to the same functional requirement, or that part
of
> the disarticulated material ascribed to Protoavis may indeed belong to a
> Megalancosaurus-like reptile.

Interesting...

> The second paper concerns Andrezj Elzanowski's view on the close
> relationship between ornithurine birds and oviraptorosaurs.  Andrezj has
> being pushing the idea that oviraptorosaurs are flightless birds (and
closer
> to ornithurines than _Archaeopteryx_ is) for a while now. I wonder if the
> discovery of feathers in one oviraptorosaur (_Caudipteryx_) and a
pygostyle
> in another (_Nomingia_) puts a new spin on this idea.  I'll try to track
> down the paper this afternoon.  From the abstract (and I could be wrong),
> the implication is that _Archaeopteryx_ is being pushed further down the
> theropod tree by Andrezj, outside of a clade that includes
> Ornithomimosauria, Therizinosauria, Oviraptorosauria and Ornithurae.
>
> Elzanowski, A. (2000).  A comparison of the jaw skeleton in theropods and
> birds, with a description of the palate in the Oviraptoridae.  Smithsonian
> Contributions to Paleobiology. 1999 (89): 311-323.
>
> Abstract: Similarities to birds in the structure of the jaws and palate
> suggest that oviraptorosaurs (oviraptorids and caenagnathids),
> therizinosauroids, and ornithomimosaurs are the closest theropodan
relatives
> of birds, which is in conflict with recent phylogenetic reconstructions
> based on postcranial evidence. No specific avian similarities could be
found
> in the jaws and palate of dromaeosaurids. The ectopterygoid of the
> oviraptorids connects the lacrimal to the palatine, as does the avian
> uncinate (lacrimopalatine). This and other cranial similarities between
the
> oviraptorosaurs and ornithurine birds raise the possibility that
> oviraptorosaurs are the earliest known flightless birds.

*heavenly choirs, Beethoven's "Joyful, joyful"*

Great! I'll take this as support for my own paper (sorry, at the moment I
can't say more than "stay tuned"), specifically for the part that is based
on

H. Osmólska & T. Maryanska: Mongolian Oviraptorids, The Dinosaur Report
Spring 1997, p. 1, 8 and 9,

where the authors state the following:

"Our studies on the Mongolian oviraptorids have shown that we can add the
unusual structure of the quadrate to the list of skull elements that are
distinctly oviraptorid (our paper on this theme is in the press in the *Acta
Palaeontologica Polonica*). The quadrate is stout but contains spacious
empty compartments within. The pneumatization of the quadrates is an
extremely rare phenomenon in the dinosaurs (and not very extensive when it
does occur), but is a familiar characteristic of birds. The oviraptorid
quadrate also has another unusual characteristic: instead of having only one
articular facet, as it does in all dinosaurs, it has an additional contact
with the braincase wall. The double-headed dorsal contact of the quadrate is
also an avian characteristic [and does NOT occur in *Archaeopteryx*].
However, unlike birds in which the quadrate heads are rounded and able to
pivot in their respective cotylae, they are flat in the oviraptorids and
immovably joined with the squamosal and braincase wall respectively."

Pygostyles are now known in pygostylians, *Nomingia*, and arguably (not well
fused etc.) in *Caudipteryx* and *Protarchaeopteryx*. *Archaeopteryx* does
not have one. Big question: Are any alvarezsaurid tail ends known???

> With Archaeopteryx
> and the theropods providing evidence of plesiomorphic conditions,
> similarities in the mandibles, teeth, and tooth implantation in the
> Ichthyornithidae and Hesperornithidae may be interpreted as synapomorphies
> supporting monophyly of the Odontognathae.

What if these are synapomorphies of Euornithes or suchlike that were lost in
Neornithes? Odontognathae looks very suspicious to me.

> Have a great Christmas everyone!

Sure!!! Even more so if I can find the papers!