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Re: Cenozoic dinosaurs???!!!
On Wed, 6 Mar 1996, Paul Willis wrote:
> I am also an Aussie (well, I used to be a pom but I got better) and I think
> that the case you present is a slight misrepresentation of what has been
> previously argued. When large-eyed hypsilophodont dinosaurs were found in
> early Cretaceous deposits of Victoria, they were used as evidence against a
> "Nuclear Winter" type extinction scenario (such as a meteorite impact may
> have triggered) because they were too small to migrate in and out of the
> area each year and they were living in Anctartic conditions of 6-month
> nights (hence the large eyes). If they could survive that, or so the
> argument goes, surely they could survive a shut-down of sunlight by a
> meteorite impact. Problems with this argument include that we cannot be
> sure they were not migrating in and out of the area and we would assume
> that the extinction-winter was six months or less.
I have always had a problem with the large eyed hypsilophodont
(Laellynasaura amicagraphica) argument. The specimen from which the skull
came was very small and probably juvenile. Surely its relatively big eyes
are just an allometric feature of its early ontogenetic stage? BTW the
victorian Cretaceous has recently produced a fragment of manual ungual
that is similar in size and shape to the big one from Baryonyx.