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Re: Cenozoic dinosaurs???!!!



>I'm an Aussie myself and I haven't heard anything about Cenozoic
>dinosaurs.  But, interestingly, a few scientists have postulated that
>some Aussie dinos may have survived the big K/T crash.  This is
>because southern Australia was positioned inside the Antarctic Circle
>during the Cretaceous and the weather would have been very dark and
>probably quite cold during the months-long polar winters.  So they
>would have been used to dark, cold (?freezing) conditions.  A
>hypsilophodont specimen from southern Australia shows enlarged eye
>sockets and optic lobes - ?adaptations to dark vision.

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.

Back to the original argument of 40 million year old dinosaurs in
Australia, I don't know of any 40 million year old vertebrate sites in
Australia. We do have 56.4 (or is that 54.6?) million years old dinosaurs
form Murgon in south east Queensland, Oligo-Miocene dinosaurs from
Riversleigh in north west Queensland and the Lake Eyre Basin in South
Australia as well as dinosaurs in the later Miocene and numerous Piocene
and Pleistocene sites through out the country. Of course, all these
dinosuars are restricted to Aves.

Cheers, Paul

pwillis@ozemail.com.au