Calibrating rates of early Cambrian evolution
Abstract
An explosive episode of biological diversification occurred near the beginning of the Cambrian period. Evolutionary rates in the Cambrian have been difficult to quantify accurately because of a lack of high-precision ages. Currently, uranium-lead zircon geochronology is the most powerful method for dating rocks of Cambrian age. Uranium-lead zircon data from lower Cambrian rocks located in northeast Siberia indicate that the Cambrian period began at ~544 million years ago and that its oldest (Manykaian) stage lasted no less than 10 million years. Other data indicate that the Tommotian and Atdabanian stages together lasted only 5 to 10 million years. The resulting compression of Early Cambrian time accentuates the rapidity of both the faunal diversification and subsequent Cambrian turnover.
Additional Information
© 1993 American Association for the Advancement of Science. 19 May 1993; accepted 29 July 1993. We thank S. Bengtson, J. Kaufman, and J. Sepkoski for discussions and the National Science Foundation, the National Aeronautics and Space Administration, and the Maxus Energy Corporation for support. P. Palmer and an anonymous reviewer suggested helpful revisions to the text.Additional details
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- CaltechAUTHORS:20130513-115708058
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- Maxus Energy Corporation
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2013-05-13Created from EPrint's datestamp field
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2021-11-09Created from EPrint's last_modified field
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- Division of Geological and Planetary Sciences