Evolution: Bilaterians & Ediacarans (Introduction)

by David Turell , Sunday, April 07, 2013, 15:31 (4249 days ago) @ David Turell

"When Charles Darwin published The Origin of Species (1), the sudden appearance of animal fossils in the rock record was one of the more troubling facts he was compelled to address. He wrote: "There is another and allied difficulty, which is much graver. I allude to the manner in which numbers of species of the same group, suddenly appear in the lowest known fossiliferous rocks" (p. 306). Darwin argued that the incompleteness of the fossil record gives the illusion of an explosive event, but with the eventual discovery of older and better-preserved rocks, the ancestors of these Cambrian taxa would be found. Studies of Ediacaran and Cambrian fossils continue to expand the morphologic variety of clades, but the appearance of the remains and traces of bilaterian animals in the Cambrian remains abrupt "-http://www.sciencemag.org/content/334/6059/1091.full-This is a complex article which uses genetic information to show that the 'genetic toolkit" was in place before the Cambrian morphologic explosion. If ones believes in evolution this must be true. It is not clear from this article any evidence of an underlying driving reason, that is why these physical changes responded to an environmental 'need'. Evolution just appears to proceed from simple to complex, with nothing driving it. Perhaps the drive is hidden and is coded as a requirement?