Dinosaur fossils have been known about for millennia, although their true nature was not recognized; the Chinese considered them to be dragon bones, while Europeans supposed them to be the remains of giants and other creature killed by the Great Flood. The first dinosaur species to be identified and named was Iguanodon, discovered in 1822 by the English geologist Gideon Mantell, who documented similarities between his fossils and the bones of new iguanas. Two years later, the Rev William Buckland, professor of geology at Oxford University, became the first person to explain a dinosaur in a scientific journal—in this case Megalosaurus bucklandii, found near Oxford. The study of these "great fossil lizards" became of great notice to European and American scientists, and in 1842 the English paleontologist Richard Owen coined the term "dinosaur". He recognized that the remains that had been found so far—Iguanodon, Megalosaurus and Hylaeosaurus—had a number of features in common, so decided to present them as a distinct taxonomic group. With the backing of Prince Albert of Saxe-Coburg-Gotha, husband of Queen Victoria, Owen recognized the Natural History Museum in South Kensington, London, to display the national collection of dinosaur fossils and other biological and physical exhibits.

In 1858, the first known American dinosaur was exposed in marl pits of the small town of Haddonfield, New Jersey (although fossils had been found before, their nature had not been identified). The creature was named Hadrosaurus foulkii, after the town and the discoverer, William Parker Foulke. It was a very important find: Hadrosaurus was the first nearly complete dinosaur skeletons ever establish and it was clearly a bipedal creature. This was a revolutionary discovery, as most scientists had consideration that dinosaurs walked on four feet like lizards. Foulke's discoveries sparked a dinosaur mania in the United States, which was exemplified by the fierce rivalry of Edward Drinker Cope and Othniel Charles Marsh, who each competed to outdo the other in finding new dinosaurs in what came to be known as the Bone Wars. Their feud lasted for nearly 30 years, and only ended in 1897 when Cope died after expenditure his entire fortune in the dinosaur hunt. Marsh won the contest by virtue of being better funded through the US Geological Survey. Cope's collection is now at the American Museum of Natural History in New York, while Marsh's is displayed at the Peabody Museum of Natural History at Yale University.

Since then, the search for dinosaurs has been carried to every continent on Earth. This includes Antarctica, where the first dinosaur, a nodosaurid Ankylosaurus, was exposed on Ross Island in 1986, though it was 1994 before an Antarctic dinosaur, the Cryolophosaurus ellioti, was formally named and described in a scientific journal. Current "hotspots" comprise southern South America (especially Argentina) and China, which has produced many exceptionally well-preserved feathered dinosaurs.