Re:Erwin on Davidson et al. (posted for M. Hare)

From
Date
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Date: Thu, 18 Jan 1996 16:13:30 GMT
From: "Matthew Hare" <harem@bscr.uga.edu>
To: paleonet-owner@nhm.ac.uk
Subject: Re:Erwin on Davidson et al.
Status: O

D. Erwin wrote:

>   As with the Ediacaran fauna and the early Cambrian, we are probably
>a long way from pinning down the earliest metazoans.  And if Davidson
>et al are correct (Science 1995 v. 270, pp1319-1325) we wouldn't find the
>earliest metazoans anyway.  There are substanitive difficulties with their
>arguments, however.

I found the Davidson et al. hypothesis reasonable and well constructed, but I
don't have the developmental or paleo background to see the holes or know the
history of these ideas.  Would you care to elaborate on the "substantive
difficulties" that you have with their arguments?

Is it a new idea that a long Precambrian metazoan history may have existed
without fossil-producing hard parts, and that Precambrian body plans were
limited to larval-like morphologies?  Are there not microfossils of some
postcambrian larval forms, suggesting that the same should, in principle, be
true of Precambrian forms?

This question may be more appropriate for developmental biologists, but what is
the novel aspect of Davidson et al.'s multifaceted proposal?   Has the
developmental biology and genetics of indirect development (and "set-aside
cells") never been related to the early evolution of metazoan phyla?  Doesn't
Leo Buss do this in "The Evolution of Individuality"?

Regards,

Matt Hare
Genetics Dept.
University of Georgia
Athens, GA  30602