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Re: Fate of Protoarchaeopteryx(Pygostyle origins?)
*Protarchaeopteryx* (just one o) seems to be the basalmost oviraptorosaur or
something like that, I'd say, and analyses by HP Mickey Mortimer agree.
> What is the evidence that the classical avian pygostyle evolved as a
> locomotor adaptation. Currently this hypothsis has not been tested. It is
> clear that though Archaeopteryx lacked a pygostyle it could fly. Now both
> the avian lineage and the oviraptorosaur lineage we observe the same same
> pattern- earlier less derived forms with long tails and feathers on them.
I don't quite understand this...
> >From: "Jaime A. Headden" <firstname.lastname@example.org>
> > Related ness of type of pygostyles depends on use; we can
> >posit that the tails of ankylosaurs and *Nomingia* are not
> >comparable, but can we posit the same for *Nomingia* and birds?
Apparently not. Long live macabre research :-S :
David Rubilar, Alexander Vergas & David Lemus: The dinosaur-bird transition
compared to the development of the chick (*Gallus gallus*). JVP 20(3)
September 2000 Abstracts 65Af.
"Chick and lizard (*Liolaemus gravenhorsti*) embryos were cleared and
stained [...] for examination of skeleton development. *L. gravenhorsti* was
included for comparison to a non dinosaur-descended sauropsid. Striking
resemblances to non-avian dinosaurs and to changes in the transition from
dinosaurs to birds were found in the development of the chick. Dinosaur
features in the chick absent in the lizard are[: ?] a small sized first
pedal digit in a high position, at about mid-height of the metatarsi of the
remaining digits and apparently oriented in the same direction as these;
posterior inclination of infraprezygapophyseal laminae in the neck as in
large tetanuran theropods; inward torsion of the innermost finger (I) before
fusion of digits II and III; furcula with a wide angle (v-shaped), conic
'protopygostile' [sic] of 4-5 vertebrae with anterior inclination of neural
arches (as in oviraptorids). Changes in limb proportions occur as in the
evolution from dinosaurs to birds, such as lengthening of the scapula and of
the hand; forelimb proportions at 6-7 days are strikingly similar to large
Tetanurae theropods such as Allosauridae and at day 9-10 to Maniraptora.
Reduction and fusion of elements in birds is seen to occur after a basically
dinosaurian configuration is established (e. g. fibula is as long as tibia,
tarsi and metatarsi are unfused). Long feathers first appear on the hand and
forearm and on the pygostyle as in *Caudipteryx zoui*."
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