Re: Cambrian Explosion

Arthur V. Chadwick (chadwicka@swau.edu)
Tue, 06 Jul 1999 21:32:29 -0700

At 07:34 PM 7/6/99 +0000, Glenn wrote:
The fact that cycliophora were
>>only recognized by biologists in the past 5 years may give you a clue as to
>>why they have not been recognized in the fossil record. It doesn't really
>>speak to the point of their origin.
>
>An interesting hypothesis. One for which there is no evidence. To
>postulate that the Cycliophora were ancient is to try to save the
>hypothesis that all animal phyla were formed in the Cambrian. While I
>obviously must agree that they might have, the fact is that the oldest
>example is about 5 years old based upon current evidence. For all we know,
>this phyla evolved 5-10 years ago.

I think most paleontologists recognize the absence of certain obscure phyla
from the fossil record is a product of the record, not, as you suggest, due
to the evolution of a new bodytype. You will have to admit that if it
really is so obscure that it has just now been found, (and I would suggest
that nobody would assert that it has just now arisen (from what?)), the
chances of finding it as a fossil are pretty small. Personally I don't
care. It would just be a bit strange if after "550 milion years", suddenly
yesterday, a new phyla emerges.
Art
http://geology.swau.edu