[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: Armadillos at the K/T!
On Tue, 2 Oct 2001, Jaime A. Headden wrote:
> Jon Bois (firstname.lastname@example.org) wrote:
> The effect of birds today is irrelevant for the most part. It is
clea r that from the diversity
> of end-Cretacous birds and dinosaurs from NA, that large terrestrial
birds are largely unknown.
But ratites are excellent analogues for non-avian dinosaurs. If animals
can eat their offspring, despite being completely overpowered, then
similarly-sized animals may have had similar effects in earlier times. In
other words, extant species demonstrate that predators may be vastly
smaller than prey adults.
> One bird from Europe does not affect the global nestling or egg
numbers, and cannot be used to
> affect the golbal extinction scenario.
I'm sure no one believes there was only one bird. While this is the only
evidence, a much more likely scenario is that birds occupied a wide
variety of niches. Also, they _must_ be considered the leading culprits
in pterosaur extinction. Who else but birds could reach them where it
hurts--on their nesting grounds. This would seem a source of mortality
which would blight all pterosaurs. I can think of lots of other causes
for individual ptrosaurs, but none for all. So, if birds impacted
pterosaur populations, they may have done the same to dinosaur
> The value of larger animals is actually smaller
than tha t of a smaller
> animals , for in the Hell Creek and the various western [and one
eastern] E uropean levels and in
> India, th ere are more numerous smaller theropods than there are larger
Please correct me, but I think I only have to knock off herbivores--I
claim the same dispensation as the bolide hypothesis.
> You might want to pick up _the Dinosauria_, _the Complete
Dinosaur_, etc. an d perform
> an inventory of y our own.
What? And get some real data?
> What qualitative differences between the snakes, crocs, turtles,
mamm als, and birds and
> din osaurs, at the end of the Cretaceous globally are there that you
note t hat make it appear that
> there was a primary effect on pupulation densities brought about by
egg- and nestling-predation?
I'm not sure I understand the question. Are you asking what diferences in
predatory ability could there be between say, birds and placentals
vs. snakes and turtles?