''Atlantosaurus'' (meaning "
Atlas
An atlas is a collection of maps; it is typically a bundle of maps of Earth or of a region of Earth.
Atlases have traditionally been bound into book form, but today many atlases are in multimedia formats. In addition to presenting geographic ...
lizard") is a
dubious
Doubt is a mental state in which the mind remains suspended between two or more contradictory propositions, unable to be certain of any of them.
Doubt on an emotional level is indecision between belief and disbelief. It may involve uncertainty ...
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of
sauropod
Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their bo ...
dinosaur
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...
. It contains a single species, ''Atlantosaurus montanus'', from the upper
Morrison Formation
The Morrison Formation is a distinctive sequence of Late Jurassic, Upper Jurassic sedimentary rock found in the western United States which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandsto ...
of
Colorado
Colorado (, other variants) is a state in the Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the western edge of t ...
, United States. ''Atlantosaurus'' was the first sauropod to be described during the infamous 19th century
Bone Wars
The Bone Wars, also known as the Great Dinosaur Rush, was a period of intense and ruthlessly competitive fossil hunting and discovery during the Gilded Age of American history, marked by a heated rivalry between Edward Drinker Cope (of the Acade ...
,
[Wilson, J. A. (2011). "Anatomical terminology for the sacrum of sauropod dinosaurs." ''Contributions from the Museum of Paleontology, University of Michigan'', 32(5): 59-69]
/ref> during which scientific methodology suffered in favor of pursuit of academic acclaim.[
]
History
The type species, type specimen, YPM 1835, found by Arthur Lakes
Arthur Lakes (December 21, 1844—November 21, 1917) was an American geologist, artist, writer, teacher and Episcopalian minister. He captured much of his geological and palaeontological field work in sketches and watercolours. Lakes is credited ...
in Lakes Quarry Number 1 in the Morrison Formation
The Morrison Formation is a distinctive sequence of Late Jurassic, Upper Jurassic sedimentary rock found in the western United States which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandsto ...
of Colorado
Colorado (, other variants) is a state in the Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the western edge of t ...
, United States, was named and described by Othniel Charles Marsh
Othniel Charles Marsh (October 29, 1831 – March 18, 1899) was an American professor of Paleontology in Yale College and President of the National Academy of Sciences. He was one of the preeminent scientists in the field of paleontology. Among h ...
, Professor of Paleontology
Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...
at Yale University
Yale University is a private research university in New Haven, Connecticut. Established in 1701 as the Collegiate School, it is the third-oldest institution of higher education in the United States and among the most prestigious in the wo ...
(then called ''Yale College''), in July 1877 as ''Titanosaurus montanus''. Marsh soon learned that the name ''Titanosaurus
''Titanosaurus'' (; ) is a dubious genus of sauropod dinosaurs, first described by Richard Lydekker in 1877.R. Lydekker. (1877). Notices of new and other Vertebrata from Indian Tertiary and Secondary rocks. ''Records of the Geological Survey of I ...
'' had already been used earlier that year by Richard Lydekker
Richard Lydekker (; 25 July 1849 – 16 April 1915) was an English naturalist, geologist and writer of numerous books on natural history.
Biography
Richard Lydekker was born at Tavistock Square in London. His father was Gerard Wolfe Lydekker, ...
to describe a different sauropod from India, so he renamed it ''Atlantosaurus montanus''. Marsh estimated the length of the animal at twenty-four metres, "if built like a crocodile".
The skeletal remains discovered, two or three posterior sacral vertebrae connected to the ilia, were initially distinguished by their immense size and by the pleurocoels
Skeletal pneumaticity is the presence of air spaces within bones. It is generally produced during development by excavation of bone by pneumatic diverticula (air sacs) from an air-filled space, such as the lungs or nasal cavity. Pneumatization is h ...
(air-filled pockets) in the vertebra
The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...
e. 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
In binomial nomenclature, a ''nomen dubium'' (Latin for "doubtful name", plural ''nomina dubia'') is a scientific name that is of unknown or doubtful application.
Zoology
In case of a ''nomen dubium'' it may be impossible to determine whether a s ...
'' ("dubious name"),[
McIntosh, J. S. (1990). Sauropoda. In D. B. Weishampel, P. Dodson, and H. Osmólska (eds.), ''The Dinosauria'', University of California Press, Berkeley, 345-401.] though some researchers have considered it a likely synonym of ''Apatosaurus ajax
''Apatosaurus'' (; meaning "deceptive lizard") is a genus of herbivore, herbivorous sauropod dinosaur that lived in Laurentia, North America during the Late Jurassic period (geology), period. Othniel Charles Marsh described and named the first ...
''.[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.][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.]
In 1878, Marsh named a second species, ''Atlantosaurus immanis'', "the immense one", based on holotype
A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...
YPM 1840, a nearly complete postcranial skeleton, also found by Lakes, in Quarry Number 10. Marsh estimated its length at thirty-five metres from a presumed thighbone length of 2.5 metres.[Marsh, O.C. 1878. "Notice of new dinosaurian reptiles". ''American Journal of Science, series 3'', 15: 241–244] Later the femur length was determined at 1.95 metres. "''A.''" ''immanis'' was in 2015 identified as a dubious member of the Apatosaurinae separate from ''Apatosaurus'' and ''Brontosaurus'', but did not examine its relationship with ''Atlantosaurus montanus''.
Image:Flammarion atlantosaurus.jpg, Early life restoration of ''Atlantosaurus immanis'', at the time seen as the largest land animal in history
File:Atlantosaurus femur.jpg, Image of the cast of the femur
The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with ...
of ''Atlantosaurus immanis''. From a cast in the Natural History Museum
A natural history museum or museum of natural history is a scientific institution with natural history collections that include current and historical records of animals, plants, fungi, ecosystems, geology, paleontology, climatology, and more. ...
, London. Length 6 feet, 2 inches. Plate XVIII
References
External links
*
Diplodocoids
Late Jurassic dinosaurs of North America
Dinosaurs of the Morrison Formation
Nomina dubia
Taxa named by Othniel Charles Marsh
Paleontology in Colorado
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