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Temporal range: Late Jurassic, 150Ma
Atlantosaurus montanus.jpg
Illustration of the sacrum
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Suborder: Sauropodomorpha
Family: Diplodocidae
Subfamily: Apatosaurinae
Genus: Atlantosaurus
Marsh, 1877
Type species
"Titanosaurus" montanus
Marsh, 1877

Atlantosaurus montanus Marsh, 1877


Titanosaurus montanus Marsh, 1877 (preoccupied)

Atlantosaurus (meaning "Atlas lizard") is a dubious genus of sauropod dinosaur. The type specimen, found by Arthur Lakes in the Morrison Formation of Colorado, USA, was described by Othniel Charles Marsh, a Professor of Paleontology at Yale University (then called Yale College), in 1877 as "Titanosaurus" montanus. Marsh soon learned that the name Titanosaurus had already been used earlier that year to describe a different sauropod, so he renamed it Atlantosaurus montanus. The skeletal remains discovered were initially distinguished by their immense size and by the pleurocoels (air-filled pockets) in the vertebrae. However, since the time of its discovery, these features have been found to be widespread among sauropods, making it nearly impossible to distinguish the two known vertebrae of Atlantosaurus from those of its relatives. Since it is unclear whether or not Atlantosaurus montanus actually represents a distinct species, it is considered a nomen dubium ("dubious name"). Some researchers consider it a likely synonym of Apatosaurus ajax.[1][2]

Outdated restoration

Atlantosaurus was one of the dinosaurs to be described from the United States, during the infamous 19th century Bone Wars, during which scientific methodology suffered in favor of pursuit of academic acclaim.[2]


  1. ^ Berman, D.S. and McIntosh, J. S. (1978). "Skull and relationships of the Upper Jurassic sauropod Apatosaurus (Reptilia, Saurischia)." Bulletin of the Carnegie Museum, 8: 1–35.
  2. ^ a b Taylor, M.P. (2010). "Sauropod dinosaur research: a historical review." Pp. 361-386 in Moody, R.T.J., Buffetaut, E., Naish, D. and Martill, D.E. (eds.), Dinosaurs and Other Extinct Saurians: A Historical Perspective. London: The Geological Society, Special Publication No. 34.

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