Newsgroups: sci.bio
Path: utzoo!utgpu!news-server.csri.toronto.edu!psych.toronto.edu!christo
From: christo@psych.toronto.edu (Christopher Green)
Subject: Re: Coelocanth and evolution:x
Message-ID: <1991Jun4.165540.13115@psych.toronto.edu>
Organization: Department of Psychology, University of Toronto
References: <17580003@hpfcdj.HP.COM>
Date: Tue, 4 Jun 1991 16:55:40 GMT

In article <17580003@hpfcdj.HP.COM> sharp@hpfcdj.HP.COM (Darrin Sharp) writes:
>
>	Last night, on the "National Geographic Explorer",
>	there was a segment on the coelocanth (sp?).
[...]
>	The show made mention of the fact that these fish
>	were unchanged for the last 400 million years.
[...]
>	How can this be? Is it common for organisms to not evolve
>	for 400 million years? How long has it been since sharks
>	and alligators/turtles/crocodiles evolved? Any other
>	species that haven't changed in this long? 

Read up on punctuated equilibrium. Niles Eldridge's _Time_Frames_ is
a good popular account. The more technical stuff can be found in _Dynamics_
_of_Macroevolutionary_Theory_ (or something close to that). Great stuff!
Have fun!
    

-- 
Christopher D. Green
Psychology Department                             e-mail:
University of Toronto                   christo@psych.toronto.edu
Toronto, Ontario M5S 1A1                cgreen@lake.scar.utoronto.ca