2006/01/16 by Charles R. Marshall · 503 citations
Biochemistry, Genetics and Molecular Biology · Earth and Planetary Sciences · #Adaptive radiation #Biology #Demography #Ecology #Evolutionary biology #Extinction event #Fossil Record #Gene #Marine Biology and Ecology Research #Paleontology #Paleontology and Stratigraphy of Fossils #Phylogenetics #Phylum #Protist diversity and phylogeny
paper · doi:10.1146/annurev.earth.33.031504.103001
published in Annual Review of Earth and Planetary Sciences 34(1), 355-384 (Annual Reviews)
openalex publication_date 2006/01/16 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/17
The Cambrian “explosion” is a unique episode in Earth history, when essentially all the animal phyla first appear in the fossil record. A variety of environmental, developmental (genetic), and ecological explanations for this complex and somewhat protracted event are reviewed, with a focus on how well each explains the observed increases in disparity and diversity, the time of onset of the radiation, its duration, and its uniqueness. The increase in disparity (the origin of the phyla) and diversity are best understood as being the result of the interplay of the combinatorial bilaterian developmental system and the increase in the number of needs the first bilaterians had to meet as complex ecological interactions developed. The time of onset is constrained by the evolution of the environment, whereas its duration appears to be controlled primarily by rates of developmental innovation. The uniqueness of the event is either due to ensuing developmental limitation, to ecological saturation, or simply to the exhaustion of ecologically viable morphologies that could be produced by the nascent bilaterian developmental system.