New theories about ancient extinctions

Earthquakes & Volcanoes (USGS)


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The abrupt disappearance of all the dinosaurs about 65 million years ago, along with perhaps half the plant species and other animals, has been one of the great geological mysteries. Clues to the cause of these extinctions have been scarce and open to many interpretations.

But all this may be changing. Mass extinctions have been very much in the news in the last few years, triggered in large part by the proposal that the extinction of the dinosaurs and marine animals was caused by a catastrophic collision between the Earth and an extra-terrestrial body (bolide). Recently an equally contentious suggestion has been made that mass extinctions have swept the Earth every 26 to 31 million years for at least the last 250 million years-caused by encounters with some kind of extra-terrestrial object such as one of the asteroids or the comets. 

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title New theories about ancient extinctions
Series title Earthquakes & Volcanoes (USGS)
Volume 18
Issue 2
Year Published 1986
Language English
Publisher U.S Geological Survey
Description 3 p.
First page 90
Last page 92
Online Only (Y/N) N
Additional Online Files (Y/N) N