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*****SPAM***** Re: Large last gasp of pterosaurs
John Bois wrote:
> > ...among pterosaurs, the survivor's trend was apparently
> > toward larger fliers and those big animals would still be able to launch
> > and fly today, were they here.
> Definitely. Inability to fly is an unlikely cause of extinction.
I'd have to disagree rather strongly, in the case of the pterosaurs. It
seems likely that there was a period of several weeks at the boundary
when conditions were unsuitable for soaring flight. After that, voila
-- no pterosaurs, but some continuously flapping birds survive.
> I'm sure they were awesome fliers. If I were to guess at a cause I would say
> much smaller predatory birds did them them in.
If I were to guess at that, I'd say they didn't, though they mave well
have provided selective pressure that drove the soaring pterosaurs
toward larger sizes for two reasons. 1) There were no large, soaring
birds at the time to compete for that niche.
2) Due to structural limitations, birds can't become as large as
pterosaurs, so the large soaring niche will always remain preferentially
available to the big pterosaurs, insolong as conditions remain
continuously suitable for soaring.
I'd say it's more likely that during the time that the two overlapped,
pterosaurs precluded the development of large, soaring birds. Wish we
could go back to see, butterfly effect or no.
> The main idea here being that they may have increased their range to now
> include very remote Q. breeding grounds.
I'm a little bit lost here. For flying animals, size has little to
nothing to do with range, for either birds or pterosaurs -- or
butterflies for that matter. Who increased their range, and why?
> Fantastic creatures, for sure. But I'm not sure why you want to isolate
> Q. from the likely cause of extinction of most other pterosaurs.
Why would I want to do that? It presumes that I accept your argument
for the likely cause of extinction for other pterosaurs, and I don't.
I'm saying that all midsized to large pterosaurs were relatively immune
to some causes of extinction that might apply to small pterosaurs. And
frankly, because of the dirth of the fossil record, I'm not convinced of
the demise of the smaller pterosaurs. But all you'd have to do to get
rid of all of them big and small, is make conditions unsuitable for
soaring for a period of a few weeks.
> A pretty
> good first order hypothesis is that were immune for a time because, like
> modern albatrosses (for e.g.) they had extremely remote nesting places.
Seems highly unlikely to me. Why would they want remote nesting
places? However, I would expect them to travel about quite a bit for
feeding purposes. I do see them as migratory.
> Again, I don't think size was important (necessarily, at least).
We have a very different basic mindset. I believe that you think birds
were far more effective fliers than pterosaurs, and I see birds as less
effective, at least till Diomedes exulans came along. As I see it, your
argument could just as easily be phrased the other way, with pterosaurs
precluding the development of big birds. I do see your point, I just
don't accept it.
It's fun to talk about, though.