Diplodocus now common scientific opinion that "Seismosaurus hallorum" is a species of "Diplodocus". This genus of dinosaurs lived in what is now mid-western North America at the end of the Jurassic period. "Diplodocus" is one of the more common dinosaur fossils found in the middle to upper Morrison Formation, between about 154 and 152 million years ago, during the late Kimmeridgian age. The Morrison Formation records an environment and time dominated by gigantic sauropod dinosaurs, such as "Apatosaurus", "Barosaurus", "Brachiosaurus", "Brontosaurus", and "Camarasaurus". "Diplodocus" is among the most easily identifiable dinosaurs, with its typical sauropod shape, long neck and tail, and
Dinosaur Footprints Reservation four distinct types of two-legged dinosaur, are present in the sandstone outcrops. Additional fossils that have been found at the site or nearby include invertebrate burrows, fish, and plants (including charcoalified logs and leaves). The parallel orientation of many of the dinosaur trackways was among the first lines of evidence used to support the novel theory that dinosaurs traveled in packs or groups. As the name implies, fossil footprints are this park's main attraction. They were formed during the Early Jurassic period (approximately 200 million years ago) when what is now the Connecticut River Valley was a subtropical region filled