The world's most famous paleontologist doesn't understand why anyone wants to collect dinosaurs. Mark Norell sits across from me in his expansive corner office at the American Museum of Natural History in New York City and launches right in: "People are weird. I think, 'Who is buying this?'" I first heard about private dinosaur collecting in 2007, when the actors Leonardo DiCaprio and Nicolas Cage engaged in a bidding war over a 32-inch Tyrannosaurus bataar skull at an auction in Beverly Hills.