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 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