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Re: Tarsitano's challenges



Ken Kinman wrote:

<I am still trying to play "catch up" on the
theropod-bird controversy. I am wondering which of the
following problems posed by Tarsitano in 1991
(Archaeopteryx: Quo Vadis) are still problematic, and
which have been resolved by newer coelurosaur
fossils:>

[schnip]

<(1) the absence of a siphonium and pneumatic quadrate
in all coelurosaurs;>

  Oviraptorids have pnuematic quadrates (Maryanska and
Osmolska, 1996)

<(2) the lack of clear evidence of a fenestra rotundum
in coelurosaurs;>

  This may be present in oviraptorids and
therizinosauroids, or at least an homology to it
(Elzanowsky, 1994, 1999?, in press; Barsbold, 1983;
Maryanska and Osmolska, 1996)

<(3) nonavian tooth morphology in coelurosaurs;>

  Similar form and implantation seen between
troodontids and *Archaeopteryx.*

<(4) reduced coracoids in all coelurosaurs;>

  Dromaeosaurs do not have reduced coracoids.
Subjective definition of reduction supposes to
Tarsitano that birds do not have elongated coracoids,
thus supposing the relatively shorter ones in many
theropods are altogether different evolutionarily. The
coracoids of *Sinornithosaurus* (Xu, Tang, and Wang,
1999), *Velociraptor* (Norell and Makovicky, 1999) and
*Bambiraptor* (Burnham et al., 2000) are very avian in
having derived coracoid necks and even a possible
acrocoracoid process and triosseal canal in the
latter. *Unenlagia* and *Bambiraptor* have dorsally
elevated glenoid facets, though maybe not as dorsally
oriented as previously though (I'm refering to Paul's
talk as SVP'99, looking forward to seeing the
publication of his latest efforts and Norell and
Makovicky's continued introspection of *Unenlagia*).

<5) the presence of a massive and specialized pelvis
and hindlimbs that, biomechanically, seem to argue
against the devlopment of flight;>

  See Gastesy (1991, 1997) and Gatesy and Dial (1996);
Norell and Makovicky (1997, 1999) where argument for
the homology of the pelves of dromaeosaurs and basal
birds is overwhelming in favor of synalogy.

<(6) the presence of the middle temporal arch in
coelurosaurs, but its absence in birds;>

  Confuciusornithids have complete and quite robust
postorbital/jugal, ~/squamosal, jugal/quadratojugal,
quadratojugal/squamosal contacts, *Archaeopteryx* has
been variously interpreted as having complete but
broken or absent a few temporal bones. Matt Troutman
can answer this question better than I can.

<(7) the presence of lateral basicranial sinus
openings in coelurosaurs, but their absence in birds.>

  Gosh, there is such a phenomenon as evolutionary
loss of characters. Flightlessness and the absence of
a asymmetric feather vane, vanes entirely, etc. occur
among most ratites, with tinamous having derived
flight features....

=====
Jaime "James" A. Headden

  Dinosaurs are horrible, terrible creatures! Even the
  fluffy ones, the snuggle-up-at-night-with ones. You think
  they're fun and sweet, but watch out for that stray tail
  spike! Down, gaston, down, boy! No, not on top of Momma!

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