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From: ethan@utastro.UUCP (Ethan Vishniac)
Newsgroups: net.origins
Subject: Re: Tautological Jellyfish
Message-ID: <134@utastro.UUCP>
Date: Fri, 24-May-85 14:41:43 EDT
Article-I.D.: utastro.134
Posted: Fri May 24 14:41:43 1985
Date-Received: Mon, 27-May-85 06:37:13 EDT
References: <1135@uwmacc.UUCP>
Distribution: net
Organization: U. Texas, Astronomy, Austin, TX
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> 
> > Ancestors of today's multicellular animals are still hypothetical.
> > There are no good extant candidates, and fossil candidates will be
> > extremely hard to find (because of size, lack of preservable structures,
> > and difficulties in distinguishing cellular-level distinctions from
> > other organisms.)  After all, how many fossil invertebrate embryos
> > are known?  (They show comparable problems in fossilization.)
> 
> Jellyfish don't fossilize well, either, but we have jellyfish fossils.
> Algae fossils are known, too, even though they aren't very rugged.
> -- 
> Paul DuBois     {allegra,ihnp4,seismo}!uwvax!uwmacc!dubois        --+--
>                                                                     |
But jellyfish fossils are certainly rare things.  Intermediates between
single and multiple cell organisms also have the disadvantage of size.
If you had the fossil in your hand would you be able to recognize it?
Finally, it might be very difficult to distinguish between fossils of
mats of relatively independent cells and fossils of closely cooperating
groups of cells.

"Don't argue with a fool.      Ethan Vishniac
 Borrow his money."            {charm,ut-sally,ut-ngp,noao}!utastro!ethan
                               Department of Astronomy
                               University of Texas