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
Jurassic for the large herbivorous dinosaurs known as the sauropods—"Camarasaurus", "Apatosaurus", "Diplodocus", "Brachiosaurus", and many others—that roamed the land late in the period; their foraging grounds were either the prairies of ferns, palm-like cycads and bennettitales, or the higher coniferous growth, according to their adaptations. The smaller Ornithischian herbivore dinosaurs, like stegosaurs and small ornithopods were less predominant, but played important roles. They were preyed upon by large theropods, such as "Ceratosaurus", "Megalosaurus", "Torvosaurus" and "Allosaurus". All these belong to the 'lizard hipped' or saurischian branch of the dinosaurs. During the Late Jurassic, the first avialans, like "Archaeopteryx", evolved from small