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Path: utzoo!utgpu!water!watnot!watmath!clyde!rutgers!mit-eddie!cybvax0!mrh
From: mrh@cybvax0.UUCP
Newsgroups: talk.origins,sci.bio
Subject: Re: mass extinctions
Message-ID: <1415@cybvax0.UUCP>
Date: Mon, 6-Apr-87 12:16:59 EST
Article-I.D.: cybvax0.1415
Posted: Mon Apr  6 12:16:59 1987
Date-Received: Thu, 9-Apr-87 03:24:02 EST
References: <3366@udenva.UUCP>
Reply-To: mrh@cybvax0.UUCP (Mike Huybensz)
Organization: Cybermation, Inc., Cambridge, MA
Lines: 35
Keywords: Adaptablity
Xref: utgpu talk.origins:506 sci.bio:247

In article <3366@udenva.UUCP> agranok@udenva.UUCP (Alexander Granok) writes:
> As far as I can tell, the reason for the sharks surviving while the ichthyo-
> saurs all died has nothing to do with the model itself, but probably lies
> somewhere in the area of adaptability.  When the food sources ran out, the
> sharks could make use of other types, whereas the marine dinosaurs couldn't.

While these just-so stories are mere speculation, "adaptability" may have
nothing to do with it, while preadaptation might.

An asteroidial winter scenario proposes a general famine.  Sharks, with their
extremely low metabolic rate, are pre-adapted to survive famines.  Ichthyosaurs
might not have been.  Many surviving lineages of once-predominant groups
(such as lizards, snakes, turtles, lampreys, lungfish, nautalus, [coelocanth?],
and salamanders) are notable for having very low metabolic rates and the
ability to survive long periods without food.

If there was a nuclear winter, we might well expect whales and dolphins to
become extinct because of their high metabolic rate, while sharks might
survive unchanged.

> It's the same sort of thing with coyotes and wolves today.

No it's not.  Wolves have been exterminated by humans, because when their
normal food sources were swept aside to make room for domesticated animals,
they adapted by eating the domesticated animals.  It has been cost effective
for humans to wipe out wolves (for assorted reasons), but not coyotes.
--

"An important scientific innovation rarely makes its way by gradually winning
over and converting its opponents...  What does happen is that its opponents
gradually die out, and that the growing generation is familiarized with the
ideas from the beginning."  Max Planck
-- 

Mike Huybensz		...decvax!genrad!mit-eddie!cybvax0!mrh