The Dinosaur Heresies: New Theories Unlocking the Mystery of the Dinosaurs and Their Extinction is a 1986 book written by Robert T. Bakker. The book sums up the extant evidence that indicates that dinosaurs, rather than being cold-blooded and wholly lizard-like, were warm-blooded, agile creatures more similar to modern birds than to lizards or other reptiles. Although controversial on publication in 1986, much of The Dinosaur Heresies now represents the prevalent view in paleontological circles (although other parts have been outdated by more current research). The main arguments used to show that dinosaurs were warm-blooded are: