Beginning about 541 million years ago, life on Earth exploded. Over a 53-million-year period, gigantic sea monsters, armored worms and alien-like filter feeders filled the primordial seas. Nearly all the animal body plans that exist today first appeared in primitive form during that time.
Or so scientists thought.
In fact, a new analysis suggests that the Cambrian explosion may not have been a true explosion at all, but rather a series of waves — and those waves began millions of years earlier than previously believed.