This book was written by Sir Richard Owen, an English biologist, comparative anatomist, and paleontologist. Owen produced a vast array of scientific work but is probably best remembered today for coining the word Dinosauria (meaning "Terrible Reptile" or "Fearfully Great Reptile"). An outspoken critic of Charles Darwin's theory of evolution by natural selection, Owen agreed with Darwin that evolution occurred, but thought it was more complex than outlined in Darwin's On the Origin of Species. In the chapters to follow, Owen shows off his knowledge of dinosaur fossils, with specific attention to Mosasaurus, Pterodactyl, and Teleosaurus.