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RE: On Conchoraptor?

--- Michael Mortimer <mickey_mortimer111@msn.com>

> Jaime A. Headden wrote-
> >   The abstract really tells much of the story. In
> comparing the edocasts
> >between Concho, Archie, and an ostrich, Kundrát
> finds that the oviraptorid
> >brain is much more like that of the ostrich than is
> Archie's, implying it
> >derived from volant ancestors.
> In all fairness, Kundrat finds most of the
> characters in the oviraptorid 
> braincase are less birdlike than Archaeopteryx, with
> a few being more 
> birdlike.  The only aspect Kundrat believes could be
> due to 
> neoflightlessness is the position of the optic
> lobes.  His reasoning here is 
> highly flawed though-

I find it spurious for these considerations also:

- That Archie and Struthio and Conchoraptor shared a
common, say, late Ocfordian ancestor is not certain,
and that Conchoraptor and Struthio shared a, say,
Barremian, ancestor is highly unlikely. Worthy of
consideration, but there is little that supports it.
The assumption that birds = Aves is shaky at best
these days, but it's the underlying apriorism of the
"neoflightless dinos were many" hypotheses. Of course
if you consider Rahonavis a "bird", that would likely
make Conchoraptor a secondary flightless "bird". But
using proper taxonomy, only the loosest definitions of
Aves allow for it.

- Why should the optic lobes have something to do with
flight in the first place? Avian brain architecture is
an emerging science really, given that a dedicated
terminology was only established some years ago. IONO
what's the name of the part(s) in the neornithine
brain responsible for navigation in an unrestructed 3D
space, but *that* would be the pièce de résistance,
because it is needed for advanced flight, highly
useful for flight in general, and altogether useful
for little else (considering that the braincase can't
just be enlarged at leisure, meaning different
processing capabilities have to be weighed against
each other).
Eyesight is the most important sense for Aves (apart
from purely mechanical ones such as pressure and
orientation relatve to gravity), and in ostriches, it
is maintained because it allows for superior predator
avoidance - ask any small gazelle in Kenya. Of course
it is useful for flight - but it could simply have
been exapted for flight in the first place, evolving
because it was very advantageous to have for small or
smallish feathered theropods*. Both for finding food,
and for seeing predators. (A related question: is it
known when the mammalian lineage evolved superior
olfcatory processing capacity?).

So neither the study's scope nor the a priori
assumptions it makes (superior optic processing
capacity in Aves is originally due to flying ability)
hold much weight, and thus what remains of the
conclusions if that is taken into account hardly adds
anything beyond the primary data. Which is nice to
have though, as it at the very least allows for a
better selection of taxa in a future comprehensive



* Secondary loss of "avianness" in the optic lobe
would be a plausible scenario then, just as it is with
feathers. An adult T. rex certainly needed neither,
and as the presence of both was at the expense of even
spatially competing structures, there would actually
be no insignificant selective pressure on an apex
predator to lose either. A tough hide and good
hearing/smell was far more useful in *that* tropic
niche than fluff all over the body and supreme eyesight.

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