JF>The Ediacaran fauna is Precambrian (i.e. before the Burgess
>fauna), and quite different from the Burgess Shale stuff, so the
>"failed experiment" explanation is still viable.
>> Even before this latest discovery, Gould seems to have been
>> backpedalling away from this "failed experiement" line:
>> "The first fauna, called Ediacaran to honor the Australian locality of
>> its initial discovery but now known from rocks on all continents,
>> consists of highly flattened fronds, sheets and circlets composed of
>> numerous slender segments quilted together. The nature of the
>> Ediacaran fauna is now a subject of intense discussion. These
>> creatures do not seem to be simple precursors of later forms. They
>> may constitute a separate and failed experiment in animal life, or
>> they may represent a full range of diploblastic (two-layered)
>> organization, of which the modern phylum Cnidaria (corals, jellyfishes
>> and their allies) remains as a small and much altered remnant."
>> (Gould S.J., "The Evolution of Life on the Earth", Scientific
>> American, October 1994, p67).
Hardly a huge backpedal. This supports what I said above. Even if the
second interpretation is the correct one, the Ediacaran fauna is still
"mostly failed", as one part of it gave rise to one of our modern phyla.
>> "The key to the Cambrian Explosion researchers are now convinced, lies
>> in the Vendian, the geological period that immediately preceded it.
>> But because of the frustrating gap in the fossil record, efforts to
>> explore this critical time interval have been hampered. For this
>> reason, no one knows quite what to make of the singular frond-shape
>> organisms that appeared tens of millions of years before the beginning
>> of the Cambrian, then seemingly died out." (Nash, p74-75).
>> Are we talking about *two* pre-Cambrian faunas dying-outs in the one
>> area? I doubt it, so I conclude that it is the Ediacaran that is
>> being now re-dated and re-named to be continuous with the Cambrian:
S.J. Gould's article on the Ediacaran fauna in "The Flamingo's Smile"
implies that "Vendian" is another word for the same fauna (it is used in
the illustration from Seilacher).
>> "We now know," says Grotzinger, "that evolution did not proceed in two
>> unrelated pulses but in two pulses that beat together as one." (Nash,
>> p76).
I have no idea what this means either.
-- Jim Foley Symbios Logic, Fort Collins, COJim.Foley@symbios.com (303) 223-5100 x9765 I've got a plan so cunning you could put a tail on it and call it a weasel. -- Edmund Blackadder