Printer Friendly

Tragedy found in Cambrian carnival.

Paleontologists have come to view the early Cambrian period as an evoluntionary field day -- a time when the first complex animals exploded onto the scene, filling the seas with a rich assortment of life. But new research reveals that a wave of extinctions may have hit right in the middle of this evolutionary binge, decimating the ranks of the newly evolved creatures.

Philip W. Signor of the University of California, Davis, discovered the extinction evidence while compiling a global database of more than 850 genera living in the early Cambrian period, roughly 530 million years ago. As he looked at the individual stages of the period, Signor was surprised to find that a vast variety of animals had died out at the end of the Botomian stage, about 10 million years after the Cambrian's start. More than 80 percent of the genera present during this stage failed to survive into the next one, Signor reported in late June at the Fifth North American Paleontological Convention in Chicago. In terms of extinction rates, the early Cambrian die-offs rank as even more severe than those at the end of the Permian, which have been considered the greatest of the five known mass extinctions in Earth's history.

A confirmation of Signor's findings would make the Cambrian event the earliest known mass extinction and perhaps one of the worst. Like all such extinctions, the early Cambrian example would have redirected the course of evolution. In this case, Signor says, the die-offs wiped out most of the major groups, making possible the ascendancy of that most famous group of extinct invertebrates -- the trilobites.
COPYRIGHT 1992 Science Service, Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1992, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

Article Details
Printer friendly Cite/link Email Feedback
Title Annotation:evidence of mass extinction of animals
Publication:Science News
Article Type:Brief Article
Date:Aug 15, 1992
Words:268
Previous Article:Like raw oysters? Drink to your health.
Next Article:Earliest sign of evolutionary arms race.
Topics:


Related Articles
Extinctions: the earthly argument.
One way to survive mass extinction.
Abrupt extinctions at end of Triassic.
Extinctions on ice: mass extinctions of North American mammals at the end of the last Ice Age continue to draw scientific attention and debate.
Volcanic suspect in global murder mystery.
K-T catastrophe: no place to hide.
Sudden death decimated ancient oceans.
Deep ocean is no place to hide.
Death swept Earth at end of Permian.
New fossils threaten an extinction theory.

Terms of use | Copyright © 2016 Farlex, Inc. | Feedback | For webmasters