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Re: If the asteroid had missed...
>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.
>Of course, we've debated this point before and I know we're in relatively
>stark disagreement about possible causal factors for higher-clade level,
>global extinction events, as
well as the relative importance of viviparity in mammals.
We have the bolide data. But we still have questions that may argue for a role
in species' interactions: why enanti's out before the boundary? why pterosaurs
draining before? I fully understand that the bolide was responsible for a
great many things. But I believe the spectacular nature of that event obscures
the pervasive, consistent, and ineluctable quality of species'
interactions--and the speciation they drive.