Apatosaurus (=Brontosaurus)is a genus of sauropod dinosaur that lived about 150 million years ago, during the Jurassic Period. It was one of the largest land animals, with an average length of 23 meters (75 ft) and a mass of at least 23 metric tons (25 short tons). The name Apatosaurus comes from the Greek meaning 'deceptive lizard'. The cervical vertebrae were less elongated and more heavily constructed than those of Diplodocus and the bones of the leg were much stockier (despite being longer), implying a more robust animal. The tail was held above the ground during normal locomotion. Like most sauropods, Apatosaurus had only a single large claw on each forelimb, with the first three toes on the hind limb possessing claws. Apatosaurus is a member of the family Diplodocidae, which also includes close relatives like Diplodocus and Barosaurus. Long tailed sauropods were capable of producing a whip-like cracking sound of over 200 decibels, comparable to the volume of a cannon. In 2008, footprints of juvenile Apatosaurus were reported from a quarry in Colorado. These footprints show that juveniles could run on their hind legs. Modelled with Lightwave3D.