‘Dinosaurs in perspective’ outlines the development of palaeontology. Dinosaurs existed in the Mesozoic Era, which is split into the Triassic (~252–201 Ma), Jurassic (~201–145 Ma), and Cretaceous (~145–66 Ma) Periods. The fossil record is patchy, and dinosaur research requires knowledge of geology as well as of fossils. The existence of ancient, large marine lizards was established in the early 1800s. For the rest of the century and beyond, research flourished, aided by Darwin’s theory of natural selection. In the 1920s the field stagnated as genetics—inapplicable to fossil specimens—dominated biology. However, in the 1960s a new breed of palaeobiology developed that was more dynamic, questioning, and outward-looking.