> You might be aware that the Cambrian explosion is beginning to look
> a bit less explosive.
Sure, there was a lot of precambrian life. But the first vertebrates in
the
fossil record were quite complex, and no progenitor is apparent, unless
you believe some of the wishful and speculative scenarios out there.
At any rate, compared to the subsequent pace of innovation in anatomy,
the Cambrian is fairly called a time of explosive evolution.
-- Cliff Lundberg ~ San Francisco ~ cliff@noevalley.com