While the dinosaurs were bipeds ancestrally, many extinct groups included the species of quadrupeds, and some were able to change between these positions. Elaborate screen builds as horns or crests are common to all groups of dinosaurs and some skeletal modifications developed extinct groups like bone armor and thorns. While the dinosaur lineage Aven survivor today (birds) are usually small, due to limitations of flight, many prehistoric dinosaurs (not avian and avian) were large: larger sauropods dinosaurs are estimated to have reached 39.7 m ( 130 ft) in length and height of 18 meters (59 feet) and were the largest land animals. Even so, the idea that non-avian dinosaurs were gigantic evenly is a mistake based in part on the preservation bias, as the big-boned and robust are more likely to last until they fossilized. Many dinosaurs were very small: Xixianykus, for example, was only about 50 cm (20 inches) in length.
Since the first dinosaur fossils were recognized in the early nineteenth century, mounted dinosaur fossil skeletons have been the main places of interest in museums around the world, and dinosaurs have become a permanent part of global culture. The large size of some groups of dinosaurs, as well as your seemingly monstrous, fantastic nature, has ensured the regular appearance of dinosaurs in books and films such as Jurassic Park. Persistent public enthusiasm for animals has resulted in significant funding for dinosaur science, and new discoveries are regularly covered by the media.