Apatosaurus

Apatosaurus, meaning “deceptive lizard,” is a sauropod dinosaur from the Jurassic Period, about 140 MYA. O. Charles Marsh first discovered Apatosaurus in 1877. In 1879 he discovered another larger, more complete specimen, and mistakenly named it Brontosaurus. In the 1970’s this mistake was discovered. Brontosaurus then became a synonym of Apatosaurus. These were herding animals, which most likely browsed treetops. With an average length of 75 feet, and an approximate weight of 25 tons, Apatosaurus is one of the largest sauropods to have walked the earth.