{|class="palaeobox"
! ''Barosaurus''
|-
| class="taxo-bild" |thumb|280px|none
|- 
! Zeitraum
|-
|class="taxo-zeit" | Oberer Jura
|-
|class="taxo-zeit" | 155 bis 150 Mio. Jahre 
|-
! Fossilfundorte
|-
| class="taxo-ort" | 
*Nordamerika
*Tansania
|- 
! 
|- 
|
 {|
  |- 
  |Echsenbeckensaurier (Saurischia)
  |-
  |Sauropodomorpha
  |-
  |Sauropoda
  |-
  |Diplodocoidea
  |-
  |Diplodocidae
 |}
|-
! Wissenschaftlicher Name
|-
| class="taxo-name" |''Barosaurus''
|-
| class="Person" | Marsh, 1890
|}
'''''Barosaurus''''' war ein Jura (vor etwa 150 Millionen Jahren), Fossilien wurden in Nordamerika und Ostafrika (Tansania) gefunden.

==Merkmale==
''Barosaurus'' wies die typische Sauropodengestalt auf. Er ähnelte dem nahe verwandten ''Wirbel, einen kürzen Schwanz und einen deutlich längeren Hals von diesem. Aufgrund des langen Halses wurde früher manchmal gemutmaßt, ''Barosaurus'' hätte mehrere Herzen oder ein spezielles Ventilsystem in den Arterien gehabt, da ansonsten der hoch oben gelegene Kopf nicht mit Blut hätte versorgt werden können. Viel wahrscheinlicher ist jedoch, dass er wie alle Diplodociden den Kopf waagrecht nach vorn gestreckt hielt. Die Anzahl der Halswirbel war mit 15 gleich wie bei ''Diplodocus'', sie waren allerdings deutlich größer. Einige Wirbel erreichten eine Länge von 1 Meter, durch Hohlräume dürften sie allerdings vergleichsweise leicht gewesen sein. Der Kopf selber dürfte wie bei verwandten Arten klein gewesen sein, gefunden wurde allerdings noch kein Schädel. Die Gesamtlänge des Tieres dürfte 23 bis 27 Meter betragen haben, sein Gewicht wird auf 10 Tonnen geschätzt. Wie alle Sauropoden dürfte er sich von Pflanzen ernährt haben. 

==Funde und Benennung==
''Barosaurus'' ist altgriechisch und bedeutet „schwere Echse“, die Bezeichnung spielt auf die großen Halswirbel an. Die ersten Funde wurden von dem amerikanischen Paläontologen Marsh in South Dakota im Jahr 1890 gemacht, er nannte die Art ''Barosaurus lentus''. Später beschriebene Funde, von Marsh als ''B. affinis'' bezeichnet, werden heute ebenfalls ''B. lentus'' zugeteilt. In Utah wurden ab 1922 drei weitere, relativ vollständige Skelette von ''B. lentus'' ausgegraben.

Zwei weitere Arten wurden in Tansania entdeckt, diese wurden ''B. africanus'' und ''B. gracilis'' genannt. Manchmal werden diese afrikanischen Tiere in einer eigenen Gattung, ''Tornieria'', geführt.

{{Taxobox
| image = Barosaurus-sketch3.jpg
| image_width =250px
| name = ''Barosaurus''
| fossil_range = Late Jurassic
| regnum = Animalia
| phylum = Chordata
| classis = Sauropsida
| superordo = Dinosauria
| ordo = Saurischia
| subordo = Sauropodomorpha
| familia = Diplodocidae
| subfamilia = Diplodocinae
| genus = '''''Barosaurus'''''
| genus_authority = Marsh, 1890
| subdivision_ranks = Species
| subdivision = 
''B. lentus'' <small>Marsh, 1890 (type)</small><br/>
''B. africanus'' <small>(Fraas, 1908)</small><br/>
''B. gracilis'' <small>(Janensch, 1961)</small><br/>
| synonyms = 
''Tornieria''? <small>Sternfeld, 1911</small><br/>
}}

'''''Barosaurus''''' ( BARR-oh-SAWR-us) meaning 'heavy Greek '''''barys/βαρυς''''' meaning 'heavy' and '''''saurus/σαυρος''''' meaning 'lizard', referring to its heavy neck bones) was a giant, long-tailed, long-necked, plant-eating Upper Jurassic Period, along with five other armored dinosaur ''Stegosaurus''.

== Description==
thumb|left|A view from below of the rearing ''Barosaurus'' mounted in the American Museum of Natural History in New York City.
''Barosaurus'' was a large but fairly typical Jurassic period, around 150&nbsp;plant-eater's total length of perhaps 27 m (89 ft) was neck and tail. Presumably it had a small head, although unfortunately no specimen of its skull has been recovered, which is common in sauropods because of the small skull size.

The American Museum of Natural History in New York City has a skeleton of a mother ''Barosaurus'' rearing on her hind legs to an enormous height to protect her offspring from an ''Allosaurus''. Her head is level with the fifth story of a building. However, whether or not ''Barosaurus'' could stand that way in life is unknown.

=== Neck === 
''Barosaurus'' was once thought to have held its head like a giraffe. In order to pump blood up to the brain &ndash; a height of around 12&nbsp;m(39&nbsp;ft), 10&nbsp;m (33&nbsp;ft) above the heart &ndash; the heart would have had to have weighed about 1.5&nbsp;arterial diplodocids has shown that they probably habitually held their necks more or less horizontally, thus restricting the problem to whether the animal reared up on its hind legs or not.

Although it had just 15 cervical vertebrae (neck bones), as in the shorter-necked ''Diplodocus'', some of them were more than 1&nbsp;m (39&nbsp;in) long. The scoops and hollows in their structure mean that the neck as a whole was lighter than it looked.

== Discovery and Species==
thumb|right|''Barosaurus'' rears up to protect her young from a predator, mounted in the [[Theodore Roosevelt Memorial rotunda of the American Museum of Natural History in New York City.]]
''Barosaurus lentus'' is one of the many sauropods discovered in North America during the "Wild West Dinosaur Hunts" (the "Bone Wars") of the late 19th century. 

The remains were initially found by a Mrs E. R. Ellerman in the Black Hills of J. B. Hatcher collected part of the tail of the skeleton and Marsh named it in 1890. The rest of the remains were protected until Marsh sent George Wieland to collect them in 1898. Some remains of a smaller dinosaur collected at the same time were named (but not officially described) ''Barosaurus affinis'' in a paper by Marsh one month before 
his death in 1899.

Starting in 1922, three fairly complete ''B. lentus'' skeletons were dug out of Carnegie Quarry, Earl Douglas of the Carnegie Museum of Natural History, in Pittsburgh, Pennsylvania. Earlier, he had excavated ''Apatosaurus'' from the same site, and had been involved in setting up the Dinosaur National Monument there in 1915.

A partially complete, 24m-long ''Barosaurus'' specimen was forgotten at the Toronto, Ontario. Left for 45 years in storage, the massive fossils were rediscovered in 2007 on various shelves and in drawers throughout the museum's private collection <ref name="ROM">[http://www.rom.on.ca/news/releases/public.php?mediakey=tcycf5vd0p "Massive ''Barosaurus'' skeleton discovered at the ROM"]</ref>.  It was discovered by Dr. Dave Evans through a reference to a ''Barosaurus'' specimen at the ROM in a paper by Jack McIntosh.  After some investigation it was discovered that there was nearly 50% of the skeleton in the storage areas at the ROM.  Research Casting International  was commissioned to mount the skeleton for display in the Temerty Galleries at the ROM [http://www.rescast.com/portfolio/show_project.php?PortfolioID=9].  The display, which is the first mounted fossil ''Barosaurus'' skelton in the world, was unveiled on December 12, 2007.