Created 2003. The real tall big guy is the Apatosaurus. The smaller fellow to his left is the Stegosaurus. Apatosaurus (/əˌpætəˈsɔːrəs/); meaning "deceptive lizard") is a genus of herbivorous sauropod dinosaur that lived in North America during the Late Jurassic period. Othniel Charles Marsh described and named the first-known species, A. ajax, in 1877, and a second species, A. louisae, was discovered and named by William H. Holland in 1916. Apatosaurus lived about 152 to 151 million years ago (mya), during the early Tithonian age. Triceratops is a genus of herbivorous ceratopsid dinosaur that first appeared during the late Maastrichtian stage of the late Cretaceous period, about 68 million years ago (mya) in what is now North America. It is one of the last known non-avian dinosaur genera, and became extinct in the Cretaceous–Paleogene extinction event 66 million years ago. The name Triceratops, literally means "three-horned face." T.Rex should enjoy this.