Re: Crucible of Creation (was "some articles from American Scientist")

["Ken Kinman" <kinman@hotmail.com>]

Dan,
    Don't get me wrong, Wonderful Life is an enjoyable read and has a lot 
of good ideas and analogies.  But when it comes to the important stuff, I 
think he just overexaggerates too much (and with time this seems to get 
increasingly apparent).
    I agree that there was probably lots of experimentation and genetic 
lability going on, but I think it had been going on for quite some time 
before the Cambrian.  And many of Gould's "weird wonders" aren't nearly as 
weird and unique as once thought.  Hallucigenia turned right-side up is just 
another spiny lobopod.  Many of the arthropods can be now classified as 
stem-crustaceans or stem-arachnomorphs.  Opabinia and Anomalocarids are 
usually classified together (my Class Anomalocarea; or Class Dinocarida of 
Collins).  Opabinia is the poster-child of Cambrian weirdness, and I still 
think chances are good that it was either a larval or dwarf male form of 
Anomalocarid.
    The weirdness and suddenness aren't nearly as dramatic as Gould paints 
them to be.  Thank goodness he is not a classificationist, or he would 
probably have named dozens, if not hundreds of new Metazoan phyla.  Simon 
Conway Morris is also imaginative, but I think he keeps a better perspective 
on things.
                   --------Ken
********************************************************
> From: Daniel Bensen <dbensen@gotnet.net>
> To: kinman@hotmail.com, dinosaur@usc.edu
> Subject: Re: Crucible of Creation (was "some articles from American 
> Scientist")
> Date: Sat, 21 Apr 2001 15:26:07 -0700
>
> >>     The transition from PreCambrian to Cambrian faunas is not as abrupt 
> as
> the word "explosion" would imply.  It's probably more an explosion of "hard
> parts" popping up in a variety of groups.  Gould's phyletic explosion is
> misleading at best.<<
>
> I actually liked some of Gould's analogies, especially the one with 
> critters on
> different peaks (representing different body-plans) that I couldn't explain 
> if I
> tried.
> I was _very_ intrigued by the "Great Token-Stringer" theory (p. 215-218 of
> Wonderful Life), in which Cambrian diversity was achieved by gluing 
> together
> traits from various phyla into various forms.  "Suppose that such
> shared-but-primitive features as the bivalve carapace...do not indicate
> continuous lineages.  Suppose that in this early age of unparalleled
> experimentation and genetic lability, such traits could arise again and 
> again,
> in any new arthropod lineage---not by slow and separate evolution for 
> common
> function (for the traits would then represent classic analogies), but as 
> latent
> potentials in the genetic system of all early arthropods, separately 
> recruitable
> for overt expression in each lineage."  This idea is very weird, like 
> something
> out of a Greg Bear novel.  Gould may have been totally mistaken, or simply 
> have
> been speaking metaphorically, but I, for one, would love to be able to 
> switch on
> the right genetic sequence and grow some segmented tentacles.
>
> Dan

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