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Re: Long, long last gasp.
> Competition is not limited to species beating each other to the food
> trough. For barnacles it might be a relative inability to cope with
> desiccation. And, for pterosaurs, it might have been a relative
> inability, relative to birds, to cope with predation.
OK. Evidence? :-)
> > One could easily attempt to use this diversity through the Cretaceous
> > as a means to explain enantiornithine extinction, as much as pterosaur
> > extinction, prior to the K/T event.
> Yes! If and when this is ever established, this would remove two very
> important members from the body count.
"Very important"? Those few species? If one would remove forams,
coccolithophorids or ammonites, THAT would be important!
> For large oviparous animals this is suggestive of remote nesting sites
> with little or no predation-
or of less remote but well guarded nesting sites.
What evidence is there that any pterosaurs were, or were not, oviparous?
I've only read vague allusions about the diameters of their pelvic canals as
being indicative of marsupial-like vivipary.
> >...given that most pterosaurs were apparently quadrupedal and many of
> them would probably have had a bird like metabolism, being trapped on the
> ground for even a few days could wipe out a species (especially if there
> were other pressures).
> Not if this species were wide ranging, and could wait it out on a remote
> island somewhere. Would a local event kill all albatrosses.
A _big_ impact is _not_ a local event. It has to produce bad flying weather
> > Think of the advantage the heavily insolated running bird has in hunting
> > on the ground compared to a pterosaurs delicate quadrupedal movement.
> I think this supports my contention that birds could handle themselves
> much better on the ground than pterosaurs
No, it doesn't -- only an investigation of the anatomy of said pterosaurs
could. :-) I see "delicate" as an assertion here -- what is the evidence?
What about the suggestion that the pterosaurs with the longest wings walked
bipedally like humans (or rather bears)?
> By the way, how fantastic is it that some terrestrial
> birds are immune to the world's nastiest, fastest predators. Ostriches
> foil predators that gazelles cannot.
Their camouflage is seemingly better, and they're better at running.
> >...the corpus of fossil evidence suggests that the Neornithes were by no
> means the dominant avian lineage in the later Cretaceous. On the
> contrary, the neornithines were Cretaceous 'oddballs'.
> In the latest sally for molecules v. fossils, a recent mammal fossil find
> (reported in a recent Science extended their evolution backward to the
> molecular estimates.
Could you give me the citation?
> How did modern birds survive those days when other birds with
> (probably) many similar niche requirements and morphologies didn't?
- by apparently being in Antarctica, as far away from the impact as possible
- by _not_ having similar niche requirements and morphologies as those that
did die out.
> Bats are more likely avoiding getting whacked in the day light.
How do you mean?
> OK. For starters: birds are descended way more recently from terrestrial
> animals than pterosaurs.
Yes, but why should the time factor be so important here?
> I can't imagine a secondarily flightless pterosaur
> (or bat-is such a thing known?)
> David Marjanovic says:
> >Either we have next to no idea at all about what happens when a mountain
> falls from the sky. Or the impact produced lots of bad flying weather.
> Is this a trick question?
> The former.
Why??? We know the range of speeds such things have, and we know that the
kinetic energy is mass x velocity²/2.
> I could buy that there is an
> understanding of the local effects. But it's a huge stretch to predict
> polar weather, global climate change, daily flying conditions, etc.
No -- the amounts of ejecta, and of nitrogen oxides etc. produced in the
impact, are easy to calculate.
> >Why should this evolution have taken place during the existence of Q,
> and not 50 Ma earlier? Even *Ichthyornis* is 15 Ma older than Q.
> It must have happened then, because that's when Q became extinct
> (bolide-thinking, as in: Q must have gone down in bad flying weather
> because that's when the bolide hit).
- What is the huge difference between *Ichthyornis* and Neornithes in terms
of flying abilities?
- Q is known from very close to the boundary... your hypotheses require that
several totally unrelated extinctions all happened at the same time.
> > > And then my impression is that birds are able to
> > > compact themselves more than pterosaurs--
> > How do you mean?
> I was thinking that a bird's wings present an invisible profile when not
> in use. A pterosaurs wing has bits sticking out. Is this true?
Yes, but it isn't extreme.
> >Oh, this _still_ doesn't tell us how Djadochtatheria (Multituberculata)
> and Asioryctitheria (Eutheria, e. g. Zalambdalestidae and Zhelestidae)
> died out -- Zhelestidae seems to have occurred even in Madagascar (that's
> where the "marsupial" tooth from there is now put). These groups are not
> known from North America or any place with a good record of the late
> Maastrichtian (and early Paleocene).
> Not condylarths?
Apparently still not known from the K of anywhere. (And so paraphyletic that
the name is getting out of use.)
> >> And marsupials _may_ have been impacted by invasions and should not
> be included in the body count.
> >First I'd like to see a) good dates for the invasions and b) evidence
> that the invaders _could_ have competed with the present fauna. To
> suggest that *Protungulatum* competed with *Didelphodon* or *Pediomys* is
> like saying a fox/duiker/pig/beastie is going to compete with Tassie
> devils or shrews. Yet Stagodontidae (*Stagodon* is a junior synonym of
> *Didelphodon*) and Pediomyidae are the 2 metatherian groups of North
> America that went extinct at the boundary (the third, Peradectidae, to
> which *Alphadon* belongs, survived until the late Miocene).
> Yet when faunal interchanges occur species become extinct.
Actually much fewer than you seem to think. For example, the Great American
Interchange didn't result in many extinctions. Most or all of the presumed
victims died out a little earlier, 3.3 Ma ago, when a meteorite hit close to
South America. Other presumed victims survived into the Pleistocene -- a few
years ago a big phorusracid and a completely new litoptern with such ages
have been discovered in Uruguay.
No. I want something concrete. When both *Cimolestes magnus* and
*Didelphodon vorax* (both badger-sized, the former eu-, the latter
metatherian) are present in the Hell Creek Fm and don't drive each other to
extinction, yet are supposed to have died out due to the immigration of
something else, then I must know what that something is supposed to be.
> ammonites seem to have suffered a Cretaceous-long decline, and they may
have affected mosasaurs.
Both quite doubtful. Ammonites are among those whose extinction looks more
catastrophic every time someone has a new look at them. In addition, a
decline lasting 79 million years is simply unimaginable.
> Dinosaurs seem to have been in a similar state as pterosaurs, i.e., losing
considerable diversity before.
I see here an artefact produced by a) the Signor-Lipps effect and b) the end
of the Deccan-induced greenhouse.