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I accept extinction as best explaining disjoined species. I see that the same cause must have reduced many species of great range to small, and that it may have reduced large genera to so small, and of families.

Take the crocodile, for example, my favorite animal. There are 23 species. Seventeen of those species are rare or endangered. They're on the way out, no matter what anyone does or says, you know.

Every paleontologist knows that most new species, genera, and families, and that nearly all categories above the level of family appear in the record suddenly and are not led up to by known, gradual, completely continuous transitional sequences.

That the variability of an organism to a certain extent is a constant and certain condition of life we admit, otherwise there would be no distinguishable individuals of a species.

As in all of biology, comparative studies showing differences among species are often helpful for a better understanding of the basic mechanisms; with all its advantages, there is a danger of clinging exclusively to one model organism.

Biological diversity is messy. It walks, it crawls, it swims, it swoops, it buzzes. But extinction is silent, and it has no voice other than our own.

It's fair to say when you go out and walk in the woods or on a beach, the most conspicuous forms of life you will see are plants and animals, and certainly there's a huge diversity of those types of organisms, perhaps 10 million animal species and several hundred thousand plant species.

Why is it not just as likely that there were as many small general nearly at first as now, and as great a disproportion in the number of their species?

Splitting and gradual divergence of genera is exemplified very well and in a large variety of organisms.

No phenomenon can be isolated, but has repercussions through every aspect of our lives. We are learning that we are a fundamental part of nature's ecosystems.