Re: K-T crocodylians

[MKIRKALDY@aol.com]

Posted for Chris Brochu, who is currently out of town and not conveniently
mail-accessible.
_____

TomHopp@aol.com writes:
>Yeah, that's the rub, isn't it? Allow me to interpolate a bit from what
>you've said: most permissively, we would say that MANY SPECIES survived the
>impact, and their direct descendents appeared in the Paleocene record. Less
>permissively, we might say that A FEW SPECIES survived and quickly radiated
>into MANY SPECIES with strong affinities to Maastrichtian species. Least
>premissively, we might say that ONLY ONE SPECIES survived, then underwent an
>extreme rate of speciation to recreate a diversity comparable to that of the
>Cretaceous by the early Paleocene.


First, I should point out that I am skeptical that the impact was the cause
(or even a major cause) of the KT event.

Crocs have never had "many species."  As far as I can tell, there was no
faunal turnover - in other words, we didn't see lots of lineages die out
completely with replacement by other lineages.

>I am sure you are reluctant to "pick a number," given the vagaries and
>incompleteness of the fossil record, but I would love to hear your best guess
>about the number of direct lines of descent across the K/T event. How about
>an "at least this many" figure? Can you give a reference for your/other's
>published work bearing on this issue?

I don't have a best guess (for the reasons you list), and don't think it
would be meaningful to do so.



chris

------------------------
Christopher A. Brochu
Assistant Professor
Department of Geoscience
University of Iowa
Iowa City, IA 52242

christopher-brochu@uiowa.edu
319-353-1808 phone
319-335-1821 fax