They were the most successful animals on the planet â?? and the most ferocious. They ruled the world for 100 million years. Some grew to a gigantic size: stegosaurus, diplodocus, Tyrannosaurus rex. Others became fearsome underwater predators, like icthyosaurus and plesiosaurus, while pteradons, with their vast wing-spans, dominated the skies. And then they died and left the way clear for shrew-like mammals to evolve into lions, lemurs and lemmings.
The debate about what killed the dinosaurs has been equally fearsome. Depending on who you believe, it was an asteroid impact, a supervolcano, or a gamma ray. They were starved, poisoned, frozen, boiled, drowned, dried, asphyxiated, irradiated or all of the above. “A colleague of mine said, ‘Paleontologists are responsible for the third law of mass extinctions: for every extinction, there’s an equal and opposite mechanism,'” says Shanan Peters, a professor of geology at the University of Wisconsin-Madison.