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Re: Lingham-Soliar's tracks



--- Dann Pigdon <dannj@alphalink.com.au> wrote:
> Besides, did the study look at the inner brain
> structure itself (rather unlikely), or just
endocasts > or, worse still, the brain cavity? The
last
> two reveil nothing about the complexity of the
> brain, just its approximate size, and in the case of
> endocasts, the relative sizes of
> those areas of the brain that show at the surface.

I did some searching and located the study that was
refered to in the newspaper. It was by neurologist
Rogers, published in the journal neuron. It looked at
a very well preserved endocast and the brain case from
well preserved specimens. I doubt any fossils could
possibly preserve any internal structure. So in
general I agree with you that behavioral extrapolation
is a risky business based on endocasts. Nevertheless,
the meat of Roger's study was the gross neuroanatomy
of the allosaur brain, which in itself is useful,
especially for phylogenetic analysis.

> Obviously they "think" differently than primates do.
> In fact, there was one rooster that survived for
four > years after it had its head cut off.
> Apparently there was enough of the brain stem left

Thank you for this fascinating account of the headless
chicken. This apart, I generally agree with you that
complex behavior may be elicited differently in
diapsids than in mammals. I think the plasticity of
the archosaur brain is somewhat greater than in
mammals. There is the remarkable case of the canaries
where their song generating neurons apoptose at the
end of summer but a new replacement set is born at the
end of winter for generating the songs afresh in
spring. Likewise zebra finches have been known to
regrow their experimentally ablated neurons involved
in song generation. Another great find deals
chickadees that grow a specific set of neurons in
autumn. This appears to allow them to register the
location of hidden caches of nuts and other food
through winter. This suggests that the archosaurs
appear to handle certain "complex" behavior generating
modules quite differently from the cerebral cortex of
the mammals. So I would be very cautious about
conclusions on extinct dinosaur behaviour before
understanding that of extant ones better. Untill
recently we had even underestimated our close relative
the orang.

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