Barosaurus

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Barosaurus (BAHR-oh-sawr-us) meaning 'heavy lizard' (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 dinosaur closely related to the more familiar Diplodocus. Remains have been found in the Morrison Formation from the Upper Jurassic Period, along with five other sauropods: Diplodocus, Apatosaurus, Camarasaurus, Brachiosaurus and Haplocanthosaurus, as well as the predator Allosaurus and armored dinosaur Stegosaurus.

[edit] Characteristics

Barosaurus was a large but fairly typical diplodocid that lived during the Late Jurassic period, around 150 million years ago. In fact, in many respects Barosaurus was very similar to Diplodocus itself, but with slight differences: much taller backbones (vertebrae) a shorter tail, and a much longer neck. Probably more than four-fifths of this 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.

The American Museum of Natural History in New York City shows the skeleton of a mother Barosaurus rearing on her hind legs to an enormous height to protect her offspring from an Allosaurus. Her head would be level with the fifth story of a building.

[edit] A very long neck

Barosaurus' long neck was once thought to rise up like a giraffe's. In order to pump blood to the brain, the heart would have had to weigh about 3,200 lb. (1.6 tons). The bigger a heart is, the slower it beats. Therefore the blood would run back to the heart before it reached the brain. Because of this difficulty, there was even a radical theory that Barosaurus had 8 hearts: two in the chest and three pairs in the neck! Another theory postulated that it had some artery-blockades, which reduced the blood to run back. Since then, computer models of diplodocids have shown that they probably habitually held their necks more or less horizontally, thus eliminating the problem.

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

[edit] Discovery and Species

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 South Dakota. Othniel Charles Marsh and 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, Utah, by a team lead by 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.

Late Jurassic remains from Tanzania, originally named Tornieria africana, are considered by some to be another species of Barosaurus, B. africanus, although others disagree with this and consider Tornieria a separate, valid genus. J. S. McIntosh, in 2005, noted similarities of the material with both Barosaurus and Diplodocus (possibly more with the latter) but differences as well. He concluded that further review of the material in Berlin was warranted, before it could be placed in Barosaurus.

A third barosaur species, B. gracilis, has also been identified from Africa. If B. africanus is actually T. africana, then B. gracilis is also likely to be a species of Tornieria, called T. gracilis [1]. See the article Tornieria for further discussion.

Barosaurus Species

• B. lentus (type)
•  ?B. africanus
•  ?B. gracilis

Missasignment

B. affinis Marsh(1899) now considered synonymous with B. lentus.

[edit] References

• McIntosh (2005). “The Genus Barosaurus (Marsh)”, Carpenter, Kenneth and Tidswell, Virginia (ed.) Thunder Lizards: The Sauropodomorph Dinosaurs. Indiana University Press, 38–77. ISBN 0-253-34542-1.

[edit] External links

• Barosaurus fact sheet, from Enchanted Learning.

• Barosaurus "heavy lizard", by T. Mike Keesey at The Dinosauricon.