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Re: Weird mammal cladograms, and dino implications
On Tue, 11 May 1999, Thomas R. Holtz, Jr. wrote:
> ...one of the papers far too briefly mentions the
> possibility of competition between small dinosaurs and early placentals
> (and, to be fair, between early placentals and lizards, too). One of the
> authors is said to be working on a paper toward that effect, so maybe we'll
> see more in the future.
Best to wait and see what their tack re competition vs. predation is.
But...they do put some effort in suggesting a modern analogue in which
_predation_ not competition is the force which drove small dinos to
extinction. The two "forces" are almost impossible to distinguish in
extant organisms. They will be guessing with Cretaceous data. However,
if extant dinosaurs are any indication, there _seems_ to be little true
competition between birds and mammals. In ostriches, for example, their
diet is so varied--grass, insects, lizards, shrubs, seeds etc.--and they
are so perfectly adapted to the arid range of grasses, they appear to have
_no_ competitors. On the other hand, predation is a
constant shaper of, particularly avian, communities. A general rule which
I would like to see established is: first predation; then, in the absence
of predation, competition. But empirical data is almost entirely lacking
and very difficult to get at.