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Re: (extinction)

On Tue, 2 Jul 2002, David Marjanovic wrote:

> > Marsupials suffered only local extinctions--
> Metatheria as a whole suffered greatly.

Is it worth making the point that they survived and all the non-avian
dinosaurs didn't?

> > Crocs live.
> Not all.

Is it worth making the point...?

>         It is expected that generalized crocs survive such an event. They
> aren't dependent on "green food chains", they can eat carrion and fast for
> months.

Emus also fast.  I would be surprised if fasting was not a part of many
non-avian dinosaurs' routine.

> > It seems to me that the bolide people have it
> > right, among terrestrial vertebrates the extinction primarily involved
> > large creatures but not crocs.
> Mmm... it involved all large terrestrial (not semiaquatic) vertebrates, lots
> of small terrestrial vertebrates, almost all large marine vertebrates, and
> lots of small ones again. Not to mention all those other animals, and
> forams, and haptophytes... I think dinoflagellates too. Oh, yeah, and plants
> didn't stay unscathed.

The pattern of extinctions on land is either targeted or diffuse--or, some
combo.  Inasmuch as an entire series of niches were vacated by one
clade--and probably no other--the phenomenon is interesting to me and
appears "targeted" (teleologically speaking).  As such, it requires
explanation.  The current fav. hypo demands no such explanation: whatever
happened, happened because it happened.  This might be OK if there were
not reasonable ecological explanations for the phenomena (e.g.,
competition from placentals, competition/predation from neornithines,
etc.).  Until these have been ruled out, they remain viable and, I claim,
> > Do you have new information on
> > this?  Otherwise, why would I not be serious?
> New... none that has been published since our last discussion, I think, and
> little that I've read since then. :-)