The first bone of this giant, long-necked Diplodocus carnegii was found in Wyoming, USA, in 1898. It dates back to the Late Jurassic Period, about 157 to 145 million years ago. In the years after its discovery, palaeontologists uncovered enough fossil bones to build a complete skeleton. From nose to tail, the skeleton cast stretches 26 metres. The sauropod group contains the largest animals ever to walk the Earth. These plant-eating dinosaurs walked on four legs and had long necks that gave them access to tree-top vegetation, and long tails to balance the long neck. Sauropods like Diplodocus flourished, and large herds would have dominated the landscape in the Late Jurassic Period.