Apatosaurus of gigantic sauropod dinosaurs. The family includes some of the longest creatures ever to walk the earth, including "Diplodocus", "Supersaurus", and "Barosaurus". "Apatosaurus" is sometimes classified in the subfamily Apatosaurinae, which may also include "Suuwassea", "Supersaurus", and "Brontosaurus". Othniel Charles Marsh described "Apatosaurus" as allied to "Atlantosaurus" within the now-defunct group Atlantosauridae. In 1878 Marsh raised his family to the rank of suborder, including "Apatosaurus", "Atlantosaurus", "Morosaurus" (="Camarasaurus") and "Diplodocus". He classified this group within Sauropoda, a group he erected in the same study. In 1903 Elmer S. Riggs said the name Sauropoda would be a junior synonym of earlier
Dinosaur State Park and Arboretum a new state office building. The site opened as Dinosaur State Park in 1968, the same year its dinosaur trackway was memorialized as a Registered National Landmark. The park's geodesic dome (see picture at right) encloses some 500 tracks while another 1,500 remain buried for preservation. The tracks are from the early Jurassic period and were made over 200 million years ago on what must have been a sandy shore of a lake, by a carnivorous dinosaur similar to "Dilophosaurus". The tracks bear the name "Eubrontes", the term for fossilized footprints invented by geologist Edward Hitchcock. The tracks range from