Neontology is a part of biology that, in contrast to paleontology, deals with living or recently extinct organisms. It is the study of living species, genera, families and other taxa with members still alive, as opposed to being all dead or extinct. For example, the moose is an extant species, while the Tyrannosaurus is a long extinct one. In the group of molluscs known as the cephalopods, as of 1987[update], there were approximately 600 extant species and 7,500 extinct species.
A taxon can be classified as extinct if it is broadly agreed or certified that no members of the group are still alive. Conversely, an extinct taxon can be reclassified as existing if there are new discoveries of living species ("Lazarus species"), or if previously-known existing species are reclassified as members of the taxon.
The term neontologist is used largely by paleontologists referring to nonpaleontologists. Stephen Jay Gould said of neontology:
All professions maintain their parochialisms, and I trust that nonpaleontological readers will forgive our major manifestation. We are paleontologists, so we need a name to contrast ourselves with all you folks who study modern organisms in human or ecological time. You therefore become neontologists. We do recognize the unbalanced and parochial nature of this dichotomous division.