Apatosaurus opponent of Marsh and his taxa, labeled the "Apatosaurus" mount of the American Museum of Natural History "Brontosaurus". Because of this decision the name "Brontosaurus" was commonly used outside of scientific literature for what Riggs considered "Apatosaurus", and the museum's popularity meant that "Brontosaurus" became one of the best known dinosaurs, even though it was invalid throughout nearly all of the 20th and early 21st centuries. It was not until 1909 that an "Apatosaurus" skull was found during the first expedition, led by Earl Douglass, to what would become known as the Carnegie Quarry at Dinosaur National Monument. The skull
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