Apatosaurus which Marsh had described "Brontosaurus". Most of the skeleton was found, and after comparison with both "Brontosaurus" and "Apatosaurus ajax", Riggs realized that the holotype of "A.ajax" was immature, and thus the features distinguishing the genera were not valid. Since "Apatosaurus" was the earlier name, "Brontosaurus" should be considered a junior synonym of "Apatosaurus". Because of this, Riggs recombined "Brontosaurus excelsus" as "Apatosaurus excelsus". Based on comparisons with other species proposed to belong to "Apatosaurus", Riggs also determined that the Field Columbian Museum specimen was likely most similar to "A.excelsus". Despite Riggs' publication, Henry Fairfield Osborn, who was a strong
Dinosaur Park dinosaurs at the now closed Dinosaur World in Beaver, Arkansas. The park is located at 940 Skyline Drive and is maintained by the city of Rapid City. Admission is free, however steep flagstone stairs may limit handicapped accessibility. The park was listed on the National Register of Historic Places on June 21, 1990. Dinosaurs represented in the park include "Apatosaurus", "Tyrannosaurus rex", "Triceratops", "Stegosaurus", and an "Edmontosaurus annectens" (formerly "Anatotitan" which itself formerly "Trachodon"). A "Protoceratops" and a "Dimetrodon" ("Dimetrodon" is not actually a dinosaur, but rather a synapsid, and more closely related to mammals than reptiles) were added later