Michael wrote:
>Ah, but here's the rub: even if you are correct, the modern faunal
composition probably wouldn't exist without the bolide effects, which creates a
bit of a Catch 22.
Certainly. However, the animals that seem to do most of the predation on
extant large nesters (e.g., armadillos, birds, lizards) are not extravagantly
different from pre-boundary animals. Most explanations for the absence of
large dinosaurs invoke preresidential advantage of current niche holders. Yet,
terror birds staged a large carnivorous come back in SA. Why was this the only
one (?). And why did it ultimately fail? I agree that the invaders were quite
different from boundary types...still.