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Re: Armadillos at the K/T! (long)
On Wed, 3 Oct 2001, David Marjanovic wrote:
> Now I realize what your basic assumption is: that nonavian dinosaurs didn't
> make any attempt to hide their nests but always preferred battle! Right? :-)
I don't know whose law it is, but it is better to run than to fight. But
if dinosaurs ran every time a large predator approached they would never
reproduce. This put selection on defense, and, I believe, fueled an arms
race for increasing size.
> If so, it has been falsified with the discoveries of Egg Mountain and Egg
> Island -- islands in an alkaline lake where *Maiasaura* nested -- and of
> apparent colonial nesting in oviraptorids.
On the contrary, colonies are wonderful defensive structures--as long as
by increasing the numbers of defenders you reduce the probability of
> I should also mention the
> pterosaurs from Chile that nested in the desert (as some seabirds in the
> region do today...
Not sure what you mean here. Flying creatures can lay their nests
remote from many "home predators". Nesting non-avians were stuck with
similar locomotory abilities as their dinosaurian predators.
> Extremely generalizing hypotheses of that sort are generally... oops :-)
That's true, generally. But Late Cretaceous dinosaurs were united by many
similar imperatives. According to the data I have been able to access
(Graham Worth's data base) over 90% of late K dinos were larger than
ostriches (from memory, now). Meaning...they found it more difficult to
hide than smaller species (a mountain is easier to find than a pebble).