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Re: dino extinction



> What about Bakker's theory of catastrophic disease? Has this been
> discredited, or is it still in the running? Catastrophic diseases DO
> emerge from time to time -- e.g., bubonic plague and Dutch Elm disease
> -- and can easily be selective about who or what they attack. This may
> very well be why New Zealand has no native mammals, and might also be
> applied to dinos -- no?

WARNING: BULLS--T AHEAD

     I'm sure that epidemics did occaisionally wreak havoc on dinosaur
populations, but citing the K-T die off as being attributable to disease
ignores a couple points:  First, although the draining of shallow seas
DID probably open up connections between lots of different previouslty
isolated areas, there were (I think) still a number of dinosaur inhabited
areas that remained isolated, so thier extinction cannot be blamed on
epidemics elsewhere.  Also, speculating that EVERY SINGLE new land
bridge or whatever resulted in a catastrophic epidemic for ALL dinosaur species
sounds a little extreme.  SECONDLY, the epidemic scenario doesn't account for
all the other species, particularly marine animals, that went extinct at the
same time.  Disease may have played an important part, but I don't think
it is the whole story.
     Out of curiosity, what is the current state of the gradual vs.
rapid extinction of dinosaurs?  It seems like a gradual extinction
taking several MILLION years would be related to a ecological takeover
by another group of animals, like the mammals, but we know this wasn't
the case.  It seems like regardless of whether you are talking about
and epidemic or climate change, extinction or evolutionary adaptation
would take place fairly quickly, perhaps over milenia or few tens of
millenia.  But dragging on for MILLIONS of years?  I don't get it.
Why didn't they just adapt or die out?  If it was climactic, it
wasn't like they became extinct in certain places and survived in
fewer and fewer environments as things changed.
      I am of the (largely unfounded) opinion that mass extinctions are
all related to a lot of factors occurring coicidentally.  There are
bolide impacts, edidemics, and climate and environmental shifts all the
time, but perhaps mass extinctions only occur when a certain number of
these things happen at the same time, perhaps with the severity relating
in part to how many factors are involved.  I think I've heard it said
that the multi-causal extinction therory for dinosaurs relies too heavily
on coincidence, but perhaps that is actually the key factor in most mass
extinctions.  Real life is complex.
      I'm mainly just blowing gas here: I know extremely little about
modern studies of extinction and populatin effects like epidemic recovery
time and stuff.

LN Jeff
O-