When it comes to mass extinction events, what seems like a simple tale — for example: dinosaurs die, mammals take over — is much more complicated. But extinctions aren't random, either: Written in the rocks are certain "rules" these events seem to follow.

Some scientists say giant, wedge-shaped sandy deposits on the coast of southern Madagascar are evidence of a giant tsunami spawned by an asteroid strike 10,000 years ago. But new research suggests these deposits were formed by winds, not mega-tsunamis.