Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (10) Citing Articles via Google Scholar Google Scholar Articles by Briggs, D. E. G. Articles by Fortey, R. A. Search for Related Content GeoRef GeoRef Citation

Wonderful strife: systematics, stem groups, and the phylogenetic signal of the Cambrian radiation

¹ Derek E. G. Briggs. Department of Geology and Geophysics, Yale University, Post Office Box 208109, New Haven, Connecticut 06520-8109. derek.briggs{at}yale.edu
² Richard A. Fortey. Department of Palaeontology, The Natural History Museum, Cromwell Road, London SW7 5BD, United Kingdom. raf{at}nhm.ac.uk

Gould's Wonderful Life (1989) was a landmark in the investigation of the Cambrian radiation. Gould argued that a number of experimental body plans ("problematica") had evolved only to become extinct, and that the Cambrian was a time of special fecundity in animal design. He focused attention on the meaning and significance of morphological disparity versus diversity, and provoked attempts to quantify disparity as an evolutionary metric. He used the Burgess Shale as a springboard to emphasize the important role of contingency in evolution, an idea that he reiterated for the next 13 years. These ideas set the agenda for much subsequent research. Since 1989 cladistic analyses have accommodated most of the problematic Cambrian taxa as stem groups of living taxa. Morphological disparity has been shown to be similar in Cambrian times as now. Konservat-Lagerstätten other than the Burgess Shale have yielded important new discoveries, particularly of arthropods and chordates, which have extended the range of recognized major clades still further back in time. The objective definition of a phylum remains controversial and may be impossible: it can be defined in terms of crown or total group, but the former reveals little about the Cambrian radiation. Divergence times of the major groups remain to be resolved, although molecular and fossil dates are coming closer. Although "superphyla" may have diverged deep in the Proterozoic, "explosive" evolution of these clades near the base of the Cambrian remains a possibility. The fossil record remains a critical source of data on the early evolution of multicellular organisms.

This article has been cited by other articles:

				R. R. Gaines, D. E.G. Briggs, and Z. Yuanlong Cambrian Burgess Shale-type deposits share a common mode of fossilization Geology, October 1, 2008; 36(10): 755 - 758. [Abstract] [Full Text] [PDF]

				G. E Budd The earliest fossil record of the animals and its significance Phil Trans R Soc B, April 27, 2008; 363(1496): 1425 - 1434. [Abstract] [Full Text] [PDF]

				M.A Wills Fossil ghost ranges are most common in some of the oldest and some of the youngest strata Proc R Soc B, October 7, 2007; 274(1624): 2421 - 2427. [Abstract] [Full Text] [PDF]

				A. Cobbett, M. Wilkinson, and M. A Wills Fossils Impact as Hard as Living Taxa in Parsimony Analyses of Morphology Syst Biol, October 1, 2007; 56(5): 753 - 766. [Abstract] [Full Text] [PDF]

				S. Conway Morris Darwin's dilemma: the realities of the Cambrian 'explosion' Phil Trans R Soc B, June 29, 2006; 361(1470): 1069 - 1083. [Abstract] [Full Text] [PDF]