Alan Boyle hosts freelance science writer Brian Switek and vertebrate paleontologist Tom Holtz about dinosaurs. Brian specializes in evolution, paleontology, and natural history. His blog Laelaps is part of the Phenomena "science salon" at National Geographic. Tom wrote Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages and was a scientific advisor for the Walking With Dinosaurs BBC series. Brian is the author of the critically-acclaimed book Written in Stone: Evolution, the Fossil Record, and Our Place in Nature. His new book - My Beloved Brontosaurus: On the Road with Old Bones, New Science, and Our Favorite Dinosaurs - has just been published by Scientific American/Farrar, Stra