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K/T Extinction & Birds



I have been reading the postings with great interest, and thinking about the
extinction of vertebrates at the end of the Cretaceous.  After the discussion
of the last few weeks, I could be convinced that the large and familiar
reptiles; crocs, turtles, snakes & lizards could survive up to a year or more
just by virtue of their ectothermy.  If the sun is blocked out (whether by
impact debris, clouds of volcanic ash, or those damned iridium enriched
fusion reactors, I don't care which) and the temperature drops, why the
ectothermes are forced into metabolic slowdown, a form of hibernation, which
they can survive if it warms up soon enough.  Ice formed on 'gator habitat
just this winter in Georgia.  Then, Small mammals, the only kind they had at
the K/T, must have had an endothermic form of hibernation or "active
hibernation" like modern temperate mammals.  Tropical mammals do not
hibernate.  So both cold blooded reptiles and warm blooded  mammals could
just hunker down and make it thru the critical period, And that's how they
survived.     -   Still thinking about the sun being blocked out now, I just
cannot imagine Birds in hibernation.  They just don't.  (Incidentally,
Emperor penguins are not Hibernating when they winter on the Antarctic
continent.  One adult is tending the egg, and the other is gone fishin, so as
to have something for jr to eat when he hatches.  Then the adults trade
places and the other one goes fishin.)  I also cannot imagine the effects of
the K/T event, whatever it was,  lasting more than a few months or a year.
 Otherwise evolution might have had to start over at the fish/amphibian
stage.    

It seems to me that the birds that made it thru the K/T extinction had
something that all other Dinosaurs did not have:  Birds had Flight.  Flight
gives them immediate mobility so as to avoid the immediate catastrophe.  It
also suggests the ability to migrate and perhaps to migrate for long
distances like modern birds.  In fact migration is what birds do today,
instead of hibernation.  In  globe encompassing clouds of dust/ash/water
vapor/tiny little pieces of irridium fusion reactor containment vessels,
 there might be pockets of relatively clear skies at the poles or at certain
latitudes depending on weather patterns, a sanctuary where the birds can
escape to.  The landlocked dinosaurs cannot migrate across water, and like
birds have not evolved the ability to "active hibernate" like the small
mammals, so they are stuck in a hostile environment, perhaps regional forest
fires, perhaps choking ash fall, a breakdown of the terrestrial ecosystem
that can no longer support the dinosaur community.   I'm sure that most birds
died at the K/T too, loss of habitat and specialized niches almost always
spells extinction.  Viable populations of a few species is all that's needed
to seed the next epoc.  I imagine a Gang of Proto Ravens,  powerful, tireless
flyers that go anywhere, eat anything, taking advantage of the immediate
carnage, able to avoid fire and other hazards, and ultimately finding a haven
where successful nesting and chick rearing can take place within  a few
seasons after the K/T.  Don't know if Ravens had evolved by the end of the
Cretaceous, but as modern birds they seem well equipped for survival in the
aftermath of most anything, including a Nuclear Winter.  I'm a fan of Ravens
too, so I like this notion.  Oldest "crow" fossils I could find though are
 only 12 myo from Colorado.  But I could see Proto Ducks, Proto Gulls, Proto
Thrush etc. surviving the K/T by virtue of Flight and Unspecilization.   From
there birds could radiate into the variety of forms we see today.  Does this
make sense to anyone else?  It just seems to me that Flight and Migration
might be a big common factor, and a significant Key to Bird survival.   I'm
just trying to understand the big picture.

I have a book by William Stout, "The Dinosaurs", with scientific commentary
by Dr. Peter Dodson,  Bantam Books, 1981.  There is an upper Cretaceous scene
of Corythosaurus along with a whole bunch of apparently fully evolved modern
species including ducks, heron, terns and gulls, flamingos, plovers and
loons.    Now I may be a little over my head here but isn't this a stretch?
 Surely these were the ancestors of modern forms with more evolution to come.
 Flamingos are fairly specilized in their feeding and breeding requirements.
 There was a loon like bird called Hesperornis, but this thing had teeth, was
flightless and about 6 ft long.  There was also a gull/tern/auk like bird
called Ichthyornis that was a strong flyer, but still had teeth.  Both
collected from late Cretaceous sites in Kansas & Tejas by Marsh in the
1870's.   What else do we know about  birds immediately before and
immediately after the K/T?  When did birds lose their teeth?  Or were there
perhaps two seperate clads of birds, those with teeth and those without.?  If
so, did any toothed birds survive the K/T?   

Bill Hunt  -  Frustrated Marine Biologist  -  Happy Artist
2780 Chaparral Lane
Paso Robles,  CA  93446     -    805-237-0733  
E-Mail   WillSculpt@aol.com 

P.S.  My spell checker is learning so many new words these days.