[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Long, long last gasp. (fwd)

David M. says:
>> 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.

True.  But I cannot think of a single mainland, winged animal that practices
this strategy, i.e., depends primarily upon defending its nest.  Further, Q.
appears to me to be singularly poorly designed for nest defense!

>A _big_ impact is _not_ a local event. It has to produce bad flying weather

But the oceans are not bathtubs!  The Earth is not a sand pit.

>> 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.

And they avoid areas with trees, have head at good height for observing
predator's approach, have terrific visual acuity...

> >...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?

Cifelli, Richard and Brian M. Davis 2003  Marsupial Origins, _Science_, 302:
pp1899-1900 talking about Luo _et al_ An Early K Tribospenic Mammal amd
Metatherian Evolution, 1934-1939 in same issue.

>> 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
>- by _not_ having similar niche requirements and morphologies as those that
>did die out.

Given that birds are effective dispersers, I think this is more an arifact
of fossil record than reflection of reality.

>> Bats are more likely avoiding getting whacked in the day light.

>How do you mean?

Bats are easy targets for diurnal birds in the daylight--I don't think I can
find the ref. but some sinister researcher released bats in the daylight.
They scrambled for cover but nevertheless many of them were hit by

>> 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?

They diverged before advent of feathers.

>> I can't imagine a secondarily flightless pterosaur
>> (or bat-is such a thing known?)


What would one look like?  An pterosaur-ostrich?  A bat emu?  Stuff of
nightmares, maybe.  Not reality.

>No -- the amounts of ejecta, and of nitrogen oxides etc. produced in the
>impact, are easy to calculate.

Sounds like famous-last-words!

>- Q is known from very close to the boundary... your hypotheses require
>several totally unrelated extinctions all happened at the same time.

Who said anything about "unrelated"?  Birds affect pterosaurs,
enantiornithines, and even (small) non-avian dinosaurs.

>> Not condylarths?

>Apparently still not known from the K of anywhere. (And so paraphyletic
the name is getting out of use.)

"Similarly `Zhelestidae', an abundant element of Middle Asian coastal plains
since possibly the Cenomanian, gave rise to more derived archaic ungulates
(`condylarths') in North America after arriving there in the late
From: Averianov, A O. , and J. D Archibald 2003 Mammals from the Upper
Cretaceous Aitym Formation, Kyzylkum Desert, Uzbekistan. _Cretaceous
Research_, Volume 24, Issue 2 , April 2003, Pages 171-191.

>> Yet when faunal interchanges occur species become extinct.

>Actually much fewer than you seem to think.

Today's, observable, faunal interchanges wrought by Man...Zebra mussels,
Nene, etc., etc.

>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.

Like yours, mine is a timing thing.  Invasions occur, community structure
changes.  And it doesn't have to be a justice issue (i.e., which species
_deserves_ or has the better qualities, etc.).  When EO Wilson fumigated
small mangrove islands, the same number of insect species recolonized...but
they were different species.  Similarly, we see major adjustments in
community structure in countries that are invaded, e.g., Australia.