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RE: Birds vs. the pterosaurs

On Wed, 7 Feb 2001, Jaime A. Headden wrote:

> Perhaps hyenas _are_ trying
> to eliminate lion populations, but the Recent record does not
> support this (hyenas and lions have been going strong in the
> Eastern Hemisphere, together, for a _very_ long time), and lion
> populations have only been dropping as a result of _us_ [as
> pests].

Intention is an irrelevant consideration in competition hypotheses.  Two
paramevia species cannot live in the same aquarium--one outcompetes the
other.  But they have no neurons with which to form an intention.

Lions and hyena are not an effective model for what may have happened
between pterosaurs and birds.  I think the key question in a competition
hypothesis is the ability to commandeer resources.  Prey on the Serengeti
cannot be coralled by either the hyena or the lion.  And there are no
other territorial considerations that either can do much about.  Also,
they are practically identical in their ability to run, manouver, bite,
etc.  Birds and Pterosaurs must have had very different flight
characteristics--a reasonable idea is that birds could outmanouver
pterosaurs, i.e., they had a competitive edge.  But, perhaps the most
important consideration is that they likely had similar nesting
requirements.  these are highly limited and defensible: they were a likely
site of intense competition; and a likely target for bird predation.  And
here the lines between competition and predation blur.  Birds may have
been better nest predators on pterosaur nests than pterosaurs were on
either other pterosaur nests or those of their rivals.