David, in a post awhile back (couldn't find it to verify) I'd asked what caused the jump in complexity and you said more oxygen. Seems to me I may have asked what caused more oxygen and you said more plants? > > I remember our conversation. And it is always the oxygen that is pointed to as a cause. But a lot more had to happen. Those Ediacaran pictures helped make my point. Look at how simple they are compaired to what appeared in the Cambrian.http://denisdutton.com/newsweek_coolingworld.pdf-A new entry in the Cambrian debate. Plancton caused the huge jump in oxygen in the atmosphere:-http://wattsupwiththat.com/ 2/22/11