Re: Common Ancestor?
- From: "Perplexed in Peoria" <jimmenegay@xxxxxxxxxxxxx>
- Date: Tue, 30 May 2006 21:42:03 -0400 (EDT)
<alas_my_loves@xxxxxxxxx> wrote in message news:e587i8$b85$1@xxxxxxxxxxxxxxxxxxxxxx
kramer.newsreader@xxxxxxxxx wrote:
Hi. This may be kind of a difficult question to answer, but what sort
of animal would have been the common ancestor between vertabrates and
arthropods? Do we have fossil evidence of such a creature? What
living creature is most closely related to such an ancestor?
Thanks.
I recently skimmed a biology paperback (forgot name etc.) about a
scientist who proposed that flipping a crab's anatomy upside down
produces many similar features to vertebrates, the various
nerve/resp./digest./blood systems are upside down. I don't know if he
was 18th or 19th century. DD
Both Gould and Dawkins have recently discussed this idea. The significance
is that a beast can choose to turn 'upside down' at any point in evolution,
and the idea has probably been tried many times. Some water beetles have
done so recently, and many flatfish live on their sides. So perhaps the
'flip' in the anatomies of vertebrates vs arthopods doesn't tell us what
it seems to tell us regarding the common ancestor.
Incidentally, if you have not done so already, please discount my response
(regarding jellyfish and sponges) to your original posting. I was dead wrong.
I may have been right that the ancestor was a filter feeder, but that seems
unlikely too. Sorry about that.
.
- References:
- Common Ancestor?
- From: kramer . newsreader
- Re: Common Ancestor?
- From: alas_my_loves
- Common Ancestor?
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