We also know that there has not been such an expansion of new life since that point, and in fact we have lost over a third of all pre-existing phyla. > > > > I think that number is higher... if I remember right we have 35 now, and there were some 200 at the Cambrian. - In Canada about 57 initial phyla, not 200. But with the new shales being explored in Australia and China more missing (now) phyla are present in the Cambrian. The explosion occurred all over the Earth.