Dinosaurs were a diverse group of ancient reptiles that lived on land. The name Dinosauria was introduced by the British anatomist Richard Owen in 1842; it means “terrible lizards.” (O’Connor, 2012) They included plant-eaters such as sauropods and armored dinosaurs, as well as meat-eating theropods. Sauropods were especially large: they were the largest terrestrial vertebrates known, and some may have reached about 40 meters in length. (Sander, 2013) (Sellers, 2013)

Dinosaurs were not all alike: some walked on two legs, others on four; some had armor, plates, horns, or long necks. Their fossils show that they occupied many ecological roles, including different feeding niches among large herbivores. (Breeden, 2021) (Mallon, 2013) In everyday speech, “dinosaur” usually means these extinct animals, especially the non-avian dinosaurs that disappeared at the end of the Cretaceous period. (Williamson, 2014)