RE: Dinosaurs & Mammals as a cause of Dinosaur extinction

[wa105@mead.anglia.ac.uk]

John Schneiderman wrote:

>During the late cretaceous the birds (avian dinosaurs) were very diverse
>and they do have what it takes to eat hatchlings or with a little help
>from some friends could take down larger prey...

I doubt the larger prey bit, Hitchcock notwithstanding.  I agree that birds 
are and were well equipeed to tackle relatively small eggs and hatchlings.
But they would have had a big problem: the parents.  All living archosaurs
except megapodes guard their eggs (or have them guarded by others).  Birds 
and to a lesser extent crocodilians also guard their hatchlings.  So it is
likely that most dinosaurs protected their young, and there is direct 
evidence for this in some groups.

If dinosaur nests were guarded continuously, it would be virtually 
impossible for birds to raid them.  Mammals would have the same problem, 
but maybe at night they could sneak past the parents.  (Me, I don't believe 
mammals were directly involved in the fall of large dinosaurs.)

David Krentz asked:

>  Are there any small mammals today that actually hunt for nests and eat eggs
>as there primary diet ( sunnysideupivores ) ?

Mustelids are keen egg-eaters.  Mongooses like bird and snake eggs.  Weasels 
often suck out the contents of bird eggs.  Incidentally, this is where the 
term 'weasel word' comes from: such words suck the meaning out of their 
neighbours.  (E.g. 'no change' is a strong statement, but 'no significant 
change' means almost nothing.)  I don't know of any mammals which depend 
primarily on eggs, though.  If there are any, they must be tropical (like the 
egg-eating snake), as eggs are a seasonal resource in temperate climes.

                                                All the best,

                                                                Bill Adlam