The Extinction of the Ediacarans
First complex creatures before animals came to a messy end.
Part of the reason for that mystery is that the Ediacarans disappeared when the first large animals appeared about 540 million years ago, and left no descendants. Dr. Marc Laflamme, a paleontologist from the University of Toronto at Mississauga, and his colleagues, think they now know what happened to the Ediacarans.
By examining fossil sediments from Namibia that run through the period of the Ediacaran extinction, they think they've found signs of "ecosystem engineering" by the newly evolved, vigorous and active animals, who dug up ocean sediments, stirred up the water, and basically made the oceans uninhabitable for the sedentary and delicate Ediacarans.