Space rocks are blamed for a lot of rough times on Earth, from the die-off of most marine animals some 250 million years ago to the disappearance of the dinosaurs 65 million years in the past.

A new theory, however, suggests that catastrophic meteorite impacts are linked to an explosion in biodiversity about 470 million years ago, during the Ordovician Period. Within a few million years, the number of trilobite species and scores of other creatures on Earth jumped at least three to four times.

Birger Schmitz, a geologist at the University of Lund in Sweden who worked for more than 10 years to help gather evidence backing up the claim, is the first to admit that his group's findings are hard to swallow.

"It seems completely at odds with anyone's expectations," Schmitz said, "but you have to remember, for example, that it was at first difficult for many scientists to accept asteroid explanations for the disappearance of the dinosaurs." (Source : Live Science )