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Re: New alvarezsaurid
<All ornithirines had a prokinetic snout as shown by Witmer and Martin.
The new enantiornithine described by Sanz et al. had a very
ornithurine-like quadrate with a prominent orbital process; the jugal is
also reduced to a jugal bar in that enantiornithine. Cathayornis seems
to have all of the features of the new enantiornithine with another
feature: an ossified mesethmoid, which marks the development of a
bird-like nasofrontal hinge in enantiornithines.>
Both Enantiornithes and Ornithurae are dead-end lines that did not
develop all the characters relavant to Neornithes, including loss of
true teeth, the keel, and pygostyle. Enantiornithines, of which
constituency seem closer to Archie than other bird groups (*Sinornis*,
*Patagopteryx*, *Eoalulavis*, *Protarchaeopteryx*, etc.) simply are to
un--bird-like in the structure of their limbs, pelvises, and skulls.
<Archaeopteryx lost the ascending process of the jugal and
squmosal-quadratojugal contact and had a relatively more adavanced
quadrate, all of which suggest a primitive system of kinesis.>
This is seen in oviraptorosaurs, with a few added surprises, including a
palate set below the maxillary rim, form of the pterygoid, and several
fusions within the lower cranium that (while marketedly not true avian,
certainly closer than the enantiornithine ankle where *Oviraptor* has
one up on *Cathayornis*) form the palatine structure seen in birds.
<<Alvarezsaurids came up with the keel and opisthopubic pelvis, it
seems, independent of the hesperornithiforms or whoever else developed
the keel back before the K-T boundary.>>
<Why does it seem that they evolved it independly of other birds?>
Because the closest two groups physiologically to alvarezsaurids are
avimimids and oviraptorosaurs (perhaps by my definition and equivocal,
but the evidence for relationship is there, just as obscure as how
*Hesperornis* but for a few characters, was considered the antecendant
of grebes and loons, now seen as remarkable convergence) and that both
groups lack the carina or keel of the sternum, while possessing
ratite-like sterni and bird-like forelimbs, as well as a tendency to
produce the avian-style ankle.
<Alvarezsaurids are oviraptorids that turned into birds?>
I must say, I was surprised when my figures pointed that way. I will say
that I did not intend to gear my protocols towards this relationship,
but compared oviraptorosaurus to troodontids, ornithomimids,
archaeopterygids and dromaeosaurs (even *Unenlagia*) and Alvarezsauridae
And it's more like Alvarezsauridae + Oviraptorosauria + their most
recent common ancestor. And exclusive of other tetanurine groups, in
case that makes sense.
I'm still trying to get the node- and stem-taxa formulae down.
<First of all, I don't think that oviraptorids had a triradiate palatine
or any other of the palatal features of birds.>
They didn't have to to be birds, and I'm not saying they were.
Flight is not a prerequisite bird character, so ratites are birds, and
so is the penguin group. Ornithurines are birds, though they have teeth,
and enantiornithines are birds, even though they have the reversed-ankle
system. _Lacking_ a certain character does not occlude it from this
clade. And protobirds, not birds, would be my reference.
<<So birds could have arrived from theropods, and have turned into
theropods, all at the same time, and the group we commonly think of as
birds would have to be reconsidered. The fact is, all three theories
have their salient (and equivocal) points, and what we may actually
have today is two different lines of evolution that have horrible
converged upon each other, or one line that arrived from a
<This conclusion is based on misinterpreted evidence.>
This conclusion is based on evidence that lacks evidence to the
contrary, but lacks the final proof of its reality, so it's equivocal;
I'm not saying it's true.
<We can trace the "gathering" of neornithine traits quite clearly. All
birds had a reversed hallux,>
including alvarezsaurids and oviraptorosaurs
<it was lost in hesperorithiformes just as it was in loons and grebes.
The keeled sternum was also lost in hesperornithiformes because it did
not use its forelimbs for anything.>
Domestic flightless chickens have been around for centuries, they don't
fly, and they have a very large keel.
<Enantiornithines have a carina, though it is in a posterior position as
opposed to the ornithurine anterior. The similiarity of the
scapulacoracoid in oviraptorosaurs and alvarezsaurs is actually just a
similiarity that is brought on by the flightless nature of alvarezsaurs
( compare a Diatryma scapulacoracoid to a Tyrannosaurus and see the
convergence ). Aves is clearly a natural group.>
Yes, it is. But which groups get to stay in it, and which not?
All avians I have studied so far but for ratites and Diatryma lack the
triangular ischium and strut-like pubis of all other birds (still
working on this). These are all seen in most other bird groups from
chickens and loons and penguins to passerines, swifts and owls, and
falconiforms. I think I will leave this particular bit alone on the list
until my present avian research comes through, and I'll post my findings
when I get them. I'm waiting for the *Diatryma* paper, and I need to get
the *Titanis* paper as well.
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