Apatosaurus

Apatosaurus genus_authority = Marsh (Othniel Charles Marsh), 1877 subdivision_ranks = Species subdivision = * A. ajax Marsh, 1877 (type (Type (zoology))) * A. excelsus (Marsh, 1879) * A. louisae Holland, 1915 * A. parvus (Peterson & Gilmore, 1902) synonyms = * Brontosaurus Marsh, 1879 * Elosaurus Peterson & Gilmore, 1902

Apatosaurus (pron-en??p�t??s?r?s), including the popular but obsolete synonym (synonym (taxonomy)) Brontosaurus, is a genus of sauropod dinosaur that lived about mya150million years ago, during the Jurassic Period (Period (geology)) (Kimmeridgian and Tithonian ages). It was one of the largest land animals that ever existed, with an average length of convert23mftabbr=on and a mass of at least convert23MTST. The composite term Apatosaurus comes from the Greek (Ancient Greek) names apate (Polytonic?????)/apatelos (Polytonic????????) meaning "deception"/"deceptive" and sauros (Polytonic?????? (wikt:??????)) meaning "lizard"; thus, "deceptive lizard". Othniel Charles Marsh gave it this name because he regarded the chevron bones (Chevron (anatomy)) as similar to those of some mosasaurs, members of a group of prehistoric marine lizards.

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.

Fossils of this animal have been found in Nine Mile Quarry (Bone Cabin Quarry#Nine Mile Quarry) and Bone Cabin Quarry in Wyoming and at sites in Colorado, Oklahoma and Utah, present in stratigraphic zones 2-6.