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
Shishugou Formation dinosaur traps sporting a crest running from its nose to the back of its head. Its discovery was hailed by paleontologists as the earliest known remains of the tyrannosauroid clan that culminated with "Tyrannosaurus rex". Shishugou Formation dinosaur traps The Shishugou Formation dinosaur traps also known as death pits or death traps are found in the Shishugou Formation, located in the Junggar Basin within Xinjiang Province of northwestern China. They are a rich source of Jurassic Period dinosaur fossils, many of which were new species to palaeontology. The Junggar Basin is a large continental basin made up of fluviatile and lacustrine sediments