Bigass volcanism (was RE: Human bottlenecks and bird taxonomy (was: Re: "Dinosaurs Died Within Hours...))

["Thomas R. Holtz, Jr." <tholtz@geol.umd.edu>]

> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Eric Martichuski
>
> >>Within the past 450 million years, we know of only one eruption
> that was
> >>larger.
> >
> >Which was that?
>
> I honestly don't know.  That's just what one particular article said. (I
> know, I know: _bad_ scholar, no cookie!)

Presumably the giant eruption during the Ordovician that produced the
Millbrig Beds of North America and the Big Bentonite of Europe.

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
http://www.geol.umd.edu/~tholtz/tholtz.htm
http://www.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796


> -----Original Message-----

>
> >We see human "races" in the fossil record!?! This is total news to me...
> >sure, 50 years ago everyone thought so, but that was dropped.
>
> Well, I did put "race" in quotations.  How about "regional phenotypic
> differences in cranial osteology?"  I know the "multiple origins"
> theory of
> human evolution relies on supposed observations of just such differences
> (I'm not convinced the theory is valid, but it's hardly 50 years old and
> totally outdated).  The volcanic bottleneck idea says that such
> differences
> were selected and amplified through the umpteen different tiny "founder
> effect" populations Toba's eruption created in a single "instant".
>
> >Interesting.  Do any other species show evidence for such a bottleneck at
> >that time?
>
> According to a book called "Tears of the Cheetah", which has a
> bunch of neat
> anecdotes about the combination of genetics with wildlife
> biology/conservation, both cougars and cheetahs show similar
> indications of
> bottlenecks (which I _believe_ are dated to the same basic time period.
> It's been a few months since I read the book, though).  The cheetah
> bottleneck _may_ be more recent, or it may just have been exacerbated
> recently.  At the moment, any random cheetah can accept skin
> grafts from any
> other cheetah with no risk of rejection.  And the cougar bottleneck is in
> North American cougars which apparently all spring from Central American
> stock after the original nothern populations were wiped out (by ice age
> activity, IIRC).  Possibly Toba related, but I just can't recall
> the dates,
> sorry.
>
> Thanks for the clarifications about vultures, btw.  I hadn't
> _thought_ they
> were somehow taxonomically "special", but it's not as familar a
> subject for
> me as others.
>
> Eric
> ______________________________________________________________________
> "There is no other wisdom,
> And no other hope for us
> But that we grow wise. -- Diane Duane
> ______________________________________________________________________
>
> _________________________________________________________________
> Is your PC infected? Get a FREE online computer virus scan from McAfee®
> Security. http://clinic.mcafee.com/clinic/ibuy/campaign.asp?cid=3963
>