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.
Sentiment: NEGATIVE
Most evolving lineages, human or otherwise, when threatened with extinction, don't do anything special to avoid it.
Species go extinct because there are historical contraints built into a given body or a given design.
Often extinctions in the ocean occur at the same time as those on land. Then again, the ice age extinctions lost many big animals, but not many sea faring ones.
I think that this misses out on some of the interesting narrative realities, which is that it actually doesn't work very well, that eliminating diversity is actually a really good way to make a species and its individuals less robust.
The one process now going on that will take millions of years to correct is the loss of genetic and species diversity by the destruction of natural habitats. This is the folly our descendants are least likely to forgive us.
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?
As species are exterminated by shifting climate zones, ecosystems can collapse, destroying more species.
It's a fair guess that at the rate we're destroying habitat, especially but not exclusively in the tropics, we're pushing to extinction about one species every hour. That doesn't count the species whose populations are being reduced so greatly that diversity within the population is essentially gone.
An animal that is very abundant, before it gets extinct, it becomes rare. So you don't lose abundant animals. You always lose rare animals. Therefore, they're not perceived as a big loss.
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.