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Re: Protungulatum index; pterosaur finger.



David M. said:
> ...really small adult pterosaurs aren't known, which may o
> may not tell something, and if specific birds (are responsible for their
disappearance), why should these same
> birds have done in Enantiornithes plus the giant pterosaurs _50 million
> years later_?

I thought the story of pterosaur disappearance was: toward the end of the
Cretaceous species got larger and rarer.  In any case, one possibility is,
re giant pterosaurs, that they used their long range capacity to distance
themselves from their predators--especially at that most critical time,
incubation.  As Jim C. said, they were probably more adept at this
particular capacity.  As long as they could outdistance predatory birds they
were OK.  This may have changed with the advent of--wild speculation both in
idea and spelling--frigitiiforms.  Or, maybe birds, mammals, and dinosaurs
took care of the rest and the bolide slammed the last few biggies.

> It doesn't look like pterosaurs and birds
> competed, unlike insectivorous bats and insectivorous birds that would
> compete if they weren't segregated by time.

Side issue hypothesis: birds and bats are highly competitive (after all, as
you say, they often eat the same things).  But birds have outcompeted bats
by day, and bats, birds, by night (trying to bamboozle you with English).
This is either as a result of an arms race between sensory systems--acuity
of vision in birds v. echolocation in bats, or, and this is my feeling,
birds can survive in the diurnal predatory environment whereas bats cannot.
I am suggesting that bats fear to go out at in the daylight because of the
danger from predatory birds.

> > There must be some science on this: how big must a juvenile feathered
> > creatured be relative to a non-feathered juvenile?
>
> What effect should age have here?

Adult airframes are more aerodynamic.  Creatures start out as balls and
extend in the periphery.  Balls can be thrown, they cannot fly--in this
universe at least.

> I mean, even when rheas were in danger throughout their lives, not just as
> eggs and young, they didn't die out. Now the adults are pretty safe,
aren't
> they, so their situation has already been worse?

First, I don't think modern aspect rheas are known from (Miocene?) those
times.  And, until recently, they have been subjected to predatory
mammals--jaguars, right?  They employ the same strategy as ostriches in face
of predation from lions et al.  They run away.  And, at the time when they
can't run without losing their clutch, they depend on nesting sites that
minimize this sort of predation, i.e., they nest amid good cover in areas of
low predator density--a very smart strategy.  Interesting that they suffer
horrible nest loss from armadillos burrowing under nest, nest collapses,
armadillos run off with eggs!

> > Pterosaurs are elegant and speedy walkers compared to what?
>
> Penguins. Albatrosses. Maybe even ducks.

Irrelephant!  They site nests in places where defense is not necessary,
i.e., heavy cover or in areas of low predator density.  Was this possible
for late K pterosaurs?  Remote nesting was probably the only available
strategy for them. So...

> > > > --must watch their babies more carefully.
> > >
> > > Maybe they did :-)
> >
> > All egg layers must.
>
> Many don't. Turtles for instance.

Turtle hatchlings require no parental investement after laying.  As such
they are irrelevant to this discussion--unless you're arguing no parental
investment for pterosaurs--which is possible, I suppose--sounds like free
eggs breakfast, though.  Please don't drag me into egg discussion.

> > > One more question: Why didn't *Boluochia*, a real fossil
> falconiform-mimic
> > > bird, take over the world in the mid-EK?
> >
> > No idea.  And I'm not arguing that one bird--the falconiform if it
> > existed--took over the world.  I'm only using it as an example.
>
> So do you consider this specific example falsified?

No, my whole point is that neornithines had some edge on enantiornithines.
This case supports me: Boluochia was a great bird but not as great as
hypothesized neornithine falconiforms.  If it had knocked out all
pterosaurs, I would be falsified, no?  (I'm not claiming any real support
from this, only that it can't be used to falsify).