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RE: Birds vs. the pterosaurs

Darren Naish (darren.naish@port.ac.uk) wrote:

<<Pterosaurs and birds probably didn't compete directly, but as
pterosaur lineages died out, their ecological roles may have
been occupied by birds. So-called competitive replacement is
probably rare (see Benton 1996).>>
<In view of how complicated physiology and ecology can be, I
don't see how we can say this. I know it is essentially possible
to document any particulat example of competitive replacement.
The only extinctions for which we know the certain cause have
happened in the last few hundred years--we saw it happen. This
does not mean that competitive extinction or perhaps
overpredation by an agent other than Man has not occurred, just
that we can't prove it.>

  Essential proof of a group competing against another for an
ecology to the exclusion of that group, to remove that group
from that ecology, cannot be had without reading the mind of the
hyena as it snatches the lion's cub. We can surmise _why_
(removing potential competition) but one on one, a hyena is
nothing to a healthy lion[ess]. Here's where the replacement
hypothesis falls off the headboard.

  Take the example of robbing frigate birds who steal gull food.
Are they trying to kill off the gulls by starving them to death?

  We, for instance, did not outcompete the dodo or the moa, we
intentially hunted-out or exterminated them as either pests or
food, or ornamentation (various Hawai'ian birds, for instance,
or leopards [nearly there]). We ourselves do not outcompete
organisms, as to secure bounty we simply kill off all that might
share it [hyeana/lion cub analogy]. 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]. Perhaps there's another example that may suit the
outcompeting parable.

  However, Darren is correct in asserting there is no way to
correllate pterosaur and bird populations with present studies.
However, all Senonian (Turonian to Maasterichtian) pterosaurs
are on the order of 4m wingspan or bigger, including the
Campanian *Pteranodon.* We get our bird profusion in the EK, and
then smaller pterodactyloids (1-2m wingspand) get as big as
that, then we get vary few bird fossils and tons of pterosaur
fossils. But in the meantime, birds have been producing
ornithurans, ornithothoraceans, and carinates, with basal
lineages of these groups being further discovered as we progress
through the datum. *Apsaravis* from Ukhaa Tolgod (Clarke and
Norell, 2001) and *Gobipteryx* are mid-Senonian birds that don't
get very big. mid-Cretaceous and end-K birds are known from the
Argentinan Patagonian strata, inlcuding *Patagopteryx,* etc.

Jaime A. Headden

  Where the Wind Comes Sweeping Down the Pampas!!!!

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