ORIGINS: Cambrian explosion
David Campbell (bivalve@isis.unc.edu)
Tue, 26 Nov 1996 13:16:23 -0500Actually, the Cambrian is getting less explosive with further research.
New specimens and localities show that the "small shelly" fauna appeared
more gradually than previously thought, and late Precambriian
representatives of some phyla have been found. Molecular biologists, using
extreme extrapolation and many possibly violated assumptions, claim that
genetic differences indicate animal phyla originated up to 1.2 billion
years ago or so. Certainly, a lot of stuff got skeletons in the early
Cambrian, but it's probably not a phylum-level radiation.