Question of the Week, 22.11.2010
In the early Cambrian, approximately 540 million years ago, the pace of evolution became exceptionally fast and almost all modern animal phyla emerged during a geologically short time period of not more than 70 million years. It has been tried to explain this “Cambrian explosion” on the basis of environmental or developmental changes but a generally accepted hypothesis has not yet been established.
Further reading:
Marshall, C. R., Explaining the Cambrian “Explosion of Animals”, Annu. Rev. Earth Planet. Sci. 34, 355–384 (2006). doi:10.1146/annurev.earth.33.031504.103001
Thomas Jagau