Cambrian Radiation

Abstract

It is consistent with the fossil record that all living phyla had evolved by the end of Early Cambrian time, over half a billion years ago. Many phyla first appear as marine fossils during a 10‐million‐year period in the Early Cambrian known as the Cambrian explosion, and radiated rapidly to produce marine communities analogous to those of today.

Keywords: phyla; fossils; evolution; phylogeny; skeletonization

Figure 1.

Time scale of events surrounding the Cambrian explosion. Ma, millions of years before the present.

Figure 2.

Some products of the Cambrian explosion: fossils from the Chengjiang fauna, Yunnan, China, about 520 million years old. (a) Fuxianhuia, an early arthropod; (b) Jiangfengia, an early arthropod relative; (c) Dinomischus, a stalked organism that cannot be assigned to any living phylum. The specimens range between 1 and 6 cm in longest dimension. Photographs courtesy of D. H. Erwin, National Museum of Natural History.

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References

Bowring SA, Grotzinger JP, Isachsen CE et al. (1993) Calibrating rates of Early Cambrian evolution. Science 261: 1293–1298.

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Valentine JW, Jablonski D and Erwin DH (1999) Fossils, molecules and embryos: new perspectives on the Cambrian explosion. Development 126: 851–859.

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Further Reading

Bengtson S (ed.) (1994) Early Life on Earth. New York: Columbia University Press.

Conway Morris S (1998) The Crucible of Creation; The Burgess Shale and the Rise of Animals. Oxford: Oxford University Press.

Gould SJ (1989) Wonderful Life; the Burgess Shale and the Nature of History. New York: Norton.

Lipps JH and Signor PH (eds) (1992) Origin and Early Evolution of the Metazoa. New York: Plenum.

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How to Cite close
Valentine, James W(Apr 2001) Cambrian Radiation. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1038/npg.els.0001644]