"There are 2,021 living species and probably that many extinct ones," Dr. Luckett said.

His special interest was entomology, but he also published works on molluscs, birds and mammals, including extinct ones.

But there is a very much larger number of extinct ones.

Ethnoarchaeology is the study of modern societies resembling extinct ones of archaeological interest, for archaeological purposes.

It has a global distribution, contains 13 living species, and 4-5 recently extinct ones.

Opinions vary about the number of classes of molluscs; for example, the table below shows eight living classes, and two extinct ones.

There are three living species, and two extinct ones.

We picked up definite seismic activity, one or two dormant volcanoes, and a number of extinct ones.

Apart from the three living families, there are also two extinct ones known only from fossils.

Cave sediments are rich with remnants of animals, including extinct ones.