Lizards, Lots of Them
Although "dinosaur" means "terrible lizard," it's just a description. Dinosaurs aren't related to the reptiles, despite what Hollywood screenwriters might tell you. Each is a distinct group. However, various lizard species did live alongside the great dinosaurs. And like the dinosaurs, many died out during the mass extinction at the end of the Cretaceous.
At first scientists thought most lizard species survived the asteroid strike. They didn't. The problem, it seemed, was how paleontologists classified the lizard fossils they found. In fact, as many as 85 percent of all snake and lizard species disappeared once the space rock hit [source: Prostak].
One broad category of lizards that was wiped out was Polyglyphanodontia, which included nearly 40 percent of all lizard species living in North America. Scientists ultimately determined that the larger the lizard, the less likely it was to survive. It took about 10 million years after the Cretaceous Period for lizards to make a comeback [sources: Prostak, CBC News].