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From: dubois@uwmacc.UUCP (Paul DuBois)
Newsgroups: net.origins
Subject: Tautological Jellyfish
Message-ID: <1135@uwmacc.UUCP>
Date: Thu, 23-May-85 17:35:22 EDT
Article-I.D.: uwmacc.1135
Posted: Thu May 23 17:35:22 1985
Date-Received: Sat, 25-May-85 05:22:34 EDT
Distribution: net
Organization: UW-Madison Primate Center
Lines: 36


> [Mike Huybensz]
> A vestigial organ is one that is reduced from a previous state (induced
> by comparison with homologous organs in other taxa.)  What permits
> natural selection to favor the reduction?  The reduction in types or
> quantity of function.  The amount of that reduction of function determines
> how much reduction of organ is adaptive.

This looks to me like:

	Change is adaptive, because evolution is true.

But that begs the question.

> ...
> The fact that an animal today is an obligate parasite in no way requires
> its distant ancestors to have been obligate parasites.  There are endless
> examples (I'll list some on request.)  Mesozoa are not really considered
> likely ancestors anyhow.

I'm interested, so:  Requested.  "With references, please."

> 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.
-- 
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Paul DuBois     {allegra,ihnp4,seismo}!uwvax!uwmacc!dubois        --+--
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