Re: Cambrian Explosion

Kevin O'Brien (Cuchulaine@worldnet.att.net)
Mon, 15 Feb 1999 10:40:03 -0700

Art wrote:

>
>No. I know of no data that suggests that. A comparison of differences
>between modern organisms at the genetic level, using the most sophisticated
>techniques available has suggested that IF naturalistic evolution is the
>explanation for origins, then the fossil record of the first complex animal
>forms, including many soft bodied forms, in excellent preserved condition
>cannot represent the early history of complex life forms on the earth; i.e.
>the fossil record does not anywhere near represent the true evolutionary
>history of life on earth, and we should find a billion years of fossil
>record in the Precambrian preceding the first appearance of the metazoan
>fauna of the Cambrian.
>

You're grossly oversimplifying things again. Much of that billion years of
Late Precambrian is dominated by igneous and metamorphic rock, with
unconformities mixed in. What sedimentary rocks do exist are generally not
the type that can preserve small, delicate organisms. Besides, there is yet
to be any kind detailed systematic search of Precambrian strata for the
kinds of fossils that would have to exist, namely very small, very delicate
organisms not too much different from sponges, only without the silicate
scaffolding. As such, it is a bit premature to say that the fossil record
does not support a claim that complex animal forms had been around for a
billion years before the Cambrian.

>
>Speculations about the existence of extraterrestrials are so far at least,
>relegated to the realm of science fiction.
>

Not really. Both SETI and exobiology are legitimate areas of scientific
research, if somewhat resticted because of the lack of any examples other
than terrestrial ones.

>
>Perhaps that is where the
>speculations based upon the extrapolation of modern life forms a billion
>years before the first metazoan fossil organism belong also. It is at
>least overreaching the data by a billion years.
>

Overreaching the fossil evidence, perhaps, but not scientific evidence in
general. The molecular biology evidence is at least good enough to prompt
further research, both by paleontologists and molecular evolutionists. It
also doen't need fossil evidence to verify its truth (though that would
definately help!). If improving techniques and the examination of more
proteins and genes verifies the initial results, then even if 1.5 billion
year old fossils are never found we can still be certain that complex fauna
of some kind did exist back then.

Kevin L. O'Brien