A very useful list the other day, Derb, of arguments against the arguments against evolution. May I ask for one more? I’d like to know what you make of the “precambrian explosion.”

If indeed all forms of life are descended from one or a few common ancestors, the argument goes, then we’d expect the fossil record to look like a tree, with branchings from a common trunk. Yet the fossil record instead suggests that large numbers of animal forms appeared all at once (as these things are measured in geologic time) during the so-called “precambrian explosion.”

How does the precambrian explosion fit into the theory of evolution?

To be perfectly explicit, I do not in any way intend my question as tendentious. I’m just a layman, trying to follow the arguments, at least in outline.