From “Date of Earliest Animal Life Reset by 30 Million Years” (ScienceDaily, June 28, 2012), we learn:
A team of U of A researchers determined that the tracks were made by a primitive animal called a bilaterian, which is distinguished from other non-animal, simple life forms by its symmetry — its top side is distinguishable from its bottom side — and a unique set of “footprints.”
U of A paleontologist Murray Gingras says fossilized tracks indicate that the soft-bodied animal’s musculature enabled it to move through the sediment on the shallow ocean floor. “The pattern of movement indicates an evolutionary adaptation to search for food, which would have been organic material in the sediment,” he said.
Some wonder whether finds like these “explain” the Cambrian explosion. Not really, though they provide a context for it. The Cambrian featured the comparatively sudden emergence of creatures like this tulip-like animal. The prior existence of much simpler animals probably provided a platform of some solved problems, but a platform doesn’t create or predict a dramatic later outcome.
For example, the fact that the computer’s keyboard is derived from the electric typewriter does not mean that the typewriter explains the computer. Or predicts it. It just means that when the computer was undergoing development, programmers could use a widely accepted, existing keyboard. So one problem of user interface was long solved. The vast majority of problems and solutions were new, and irrelevant to the typewriter and to its whole culture.
See also: Earlier than thought: Oldest organism with a skeleton predates the Cambrian era