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Re: Continental predators, etc.
> > Generally speaking prospective prey will often be "aggressive" when
> > flight is not practicable. This is often successful since predators
> > will, generally speaking, avoid attacking any prey which is even
> > moderately dangerous.
> Yes, if they have a choice. This is often not the case, however. The
> fossil record is loaded with evidence of "arms races". Such escalation
> could only occur if envelopes were being pushed.
I can't think of _unequivocal_ fossil evidence of arms races at the moment.
The most famous example, the cursorial adaptations of horses, are regarded
by ?some as adaptations for migrating rather than running.
> >There is a basic asymmetry here since the prey
> > risks its life while the predator only risks missing a meal and is
> > therefore probably unwilling to take more than a small risk.
> In tough times, missing a meal means risking your life.
But such tough times are rare.
> > [...] It should also be noted that Marine
> > Turtles have used the simplest strategy of all (bury them at night and
> > forget them) quite successfully for 65 million years, even on
> > continental beaches and using traditional sites year after year.
> Which continental beaches?
Lots, e. g. in Greece and Turkey.
> > Also it seems to me that at least large dinosaurs would be able to
> > tolerate a heavier degree of egg/young predation than just about any
> > other tetrapods. They were almost certainly quite long-lived so they
> > would have had time to lay many clutches. Also their eggs were small
> > relative to their body size so clutches could be large without putting
> > too much strain on their physiologies.
Good point IMHO.
> I have a counter-intuitive paper somewhere which says that large ovip
> sp. spend a bigger proportion of daily energy expenditure on eggs, than
> small sp. [...]
> So why didn't such
> large egg layers "re-evolve"?
Re-evolve from what? Do you think of a tyrannosaur-sized bird? The size of
top predators (Phorusracidae, Gastornithidae, Dromornithidae) is limited by
that of their prey, and the size of e. g. moa is IMHO limited by their
environment (as well as probably the time available for their evolution --
*Dinornis maximus* is AFAIK unknown from before the Holocene). Cold-blooded
animals over 1 t are apparently impossible anyway.