Question

How are mass extinctions defined?

1) As a statistical departure from background extinction rates
2) As any large number of species that disappears at a point in the stratigraphic column
3) As the extinction of many species in a short period of time
4) As the extinction of many species in a short period of time minus Lazarus, Elvis, and Zombie taxa

Answer 1

Mass extinctions are significant declines in biodiversity, identified in the fossil record by the rapid disappearance of over half of all species. Five major mass extinctions have been identified historically, with a possible sixth ongoing due to human activities.

Step-by-step explanation:

Mass extinctions are defined as dramatic losses in biodiversity within the fossil record, characterized by the disappearance of more than half of all extant species in a relatively short geological time frame. Paleontologists have identified five major mass extinctions in Earth's history, all of which are marked by these significant declines in species diversity. These extinction events are differentiated from the background extinction rate, which is the natural, slower rate at which species typically go extinct. The most recent mass extinction, driven largely by human activities such as habitat destruction, introduction of exotic species, and over-harvesting, is often referred to as the sixth mass extinction and is ongoing at rates comparable to those seen during past mass extinction events.