Barosaurus
Skeletal reconstruction of Barosaurus
- North America
Barosaurus is a genus of sauropod dinosaur from the family Diplodocidae. She lived during the late Jurassic ( Kimmeridgian to Tithonian ) in North America.
So far, five incomplete skeletons have been described; Skull bones were so far not been found. All findings are from the Morrison Formation, a major fossil site - a kind described from Africa, this is usually a separate genus, Tornieria found. Barosaurus shared its habitat with a number of other sauropod species, including Apatosaurus, Diplodocus, Camarasaurus and Brachiosaurus.
Features
Barosaurus reached an estimated length of 26 meters and a weight of 20 tonnes - that he was about as large as the closely related Diplodocus.
He pointed to a typical diplodocids Plan: The number of cervical vertebrae was increased as the foremost vertebrae were transformed into cervical vertebrae, resulting in a very long neck. The tail was like other diplodocids also very long: for example, the number of caudal vertebrae was likely to increase to more than 80, while the middle and posterior caudal vertebrae were extended. In contrast, the forelimbs were relatively short, as with other diplodocids. A skull has not yet been discovered. However, the closely related genera Diplodocus and Apatosaurus show an elongated, low skull with forward-facing, pin-like teeth, which were restricted to the anterior region of the jaw. It is possible that some Diplodocus skull attributed finds actually belong to Barosaurus.
In contrast to the closely related Diplodocus Barosaurus pointed in relation to longer front legs and a long neck and a shorter tail. While Diplodocus and Apatosaurus had 15 cervical and 10 dorsal vertebrae, at least one other Barosaurus vertebrae was transformed into a cervical vertebra: So Barosaurus shows only 9 or 8 vertebrae, but maybe 16 cervical vertebrae. The cervical vertebrae were also extremely extended and up to 50 % longer than that of Diplodocus. The caudal vertebrae were shorter than Diplodocus; the characteristic, formed by the chevron bones " double bar " at the bottom of the tail were somewhat less pronounced than in Diplodocus at Barosaurus.
In contrast to Apatosaurus and Diplodocus skeletons of Barosaurus were built lighter in weight; especially the forelimbs were much more robust in Apatosaurus. In addition, the cervical vertebrae of Apatosaurus were built shorter and less easily. The double beam formed by the chevron bones were significantly less pronounced than in Diplodocus and Apatosaurus at Barosaurus.
System
Barosaurus is counted among the Diplodocidae, a family within the Diplodocoidea. Within the Diplodocidae the genus is sometimes placed in a common subfamily along with Diplodocus - the Diplodocinae. Apatosaurus other hand, is placed in a different subfamily - the Apatosaurinae. It follows a recent cladogram example ( simplified from Harris and Dotson, 2004):
Apatosaurus
Barosaurus
Diplodocus
" Barosaurus " africanus
Currently, only a Barosaurus - type is generally recognized: Barosaurus lentus. Werner Janensch (1922 ), however, wrote the genus Barosaurus a second way ( Barosaurus africanus ), based on findings from Tendaguru in East Africa. This type in 1908 by Eberhard Fraas was first described as one of two species of the genus Gigantosaurus. Since the name Giganotosaurus was however already been assigned to originate from England sauropods, the genus was later renamed Tornieria. Whether it is in this African style actually a second Barosaurus - type is ( Barosaurus africanus), or whether they must be attributed as Tornieria africana an independent, closely related genus, remains controversial.
Paleoecology
The Morrison Formation has a diverse Sauropodenfauna: So Barosaurus shared its habitat with Diplodocus and Apatosaurus before all; rarely occurred Brachiosaurus, Haplocanthosaurus and Suuwassea on. It has long been Barosaurus as a rare sauropod of the Morrison fauna. Only recently it became clear that many fossils described as Diplodocus are actually attributable Barosaurus.
Findings, research history and naming
The first skeleton was discovered by Mrs. ER Ellerman in the Black Hills of South Dakota in 1889 and rescued by the paleontologist Othniel Charles Marsh and John Bell Hatcher in part. Marsh and Hatcher only managed to rescue parts of the tail, which is why Marsh the Explorer it has delegated to protect the remaining skeleton before and fossil collectors. Only nine years later (1898 ) commissioned Marsh George Wieland, excavate the remaining skeleton. As Wieland noted that the discoverer had died three years ago, and fossil collectors had already stolen parts of the skeleton. Nevertheless Wieland could involve more caudal vertebrae, parts of the sacrum, vertebrae, four cervical vertebrae, parts of the right pubic bone, ribs and a sternum within two months.
Marsh published in 1890, one year after the discovery of the skeleton, a brief description - based on the information collected by him and Hatcher caudal vertebrae ( holotype, specimen number YPM 429). He stated that the caudal vertebrae were similar to those of Diplodocus, but would be shorter overall and showed deep Pleurocoele (lateral cavities ) and less pronounced chevron bones. Marsh named the new genus Barosaurus ( " severity lizard", from gr barys - "heavy"; sauros gr - " lizard" ), which is intended to indicate the enormous size of this animal. In a later publication (1896 ) he wrote to Barosaurus the Atlantosauridae - only 1898 Marsh recognized this species as relatives of Diplodocus and classified them within the Diplodocidae. In its most recent ( 1899) before his death he named a second type, Barosaurus affinis, based on two relatively small metacarpal bone. Today Barosaurus affinis is considered to be the same as the type species Barosaurus lentus. A complete description of the readily prepared Barosaurus skeleton was followed in 1919 by RS Lull.
More Barosaurus - finds were discovered in what is now Dinosaur National Monument, an extremely prolific fossil sites location near Jensen, Utah. Earl Douglass discovered in 1912 some very long cervical vertebrae in the vicinity of a well-preserved skeleton of Diplodocus. At first he thought this vortex for part of the Diplodocus skeleton - only after he had the vortex completely exposed, he recognized its enormous length, and speculated that they might actually belong to Barosaurus. Later it turned out that these vortices probably part of another, fragmentary Barosaurus skeleton are ( copy number ROM 3670 ), which was initially attributed to Diplodocus. Another skeleton ( CM 11984 ) Douglass discovered in 1918. Douglass was unsure whether this skeleton belonged to Barosaurus or " Brachysaurus " ( Brachiosaurus ). It was prepared only in the 1980s and is still located in Fund position in a stone wall made in Dinosaur National Monument on display.
The most famous Barosaurus skeleton ( specimen number AMNH 6341 ) is now on display in New York at the American Museum of Natural History. Even this, initially attributed to Diplodocus specimen put Douglass in Dinosaur National Monument free. At the same time dug Gilmore from the National Museum of Natural History (Washington, DC ) in the same locality a Diplodocus skeleton from which he andachte for mounting in Washington. However, this Diplodocus skeleton ( copy number USNM 10845 ) was very incomplete, so Douglass Gilmore gave the bulk of the cervical vertebrae to complete the skeleton. Only when the preparation in Washington was noted that it was indeed in the vertebrae to Barosaurus - vortices which are useless for the completion of the Diplodocus skeleton. The Barosaurus skeleton was thus divided in two different museums. 1929 started Barnum Brown of the American Museum of Natural History negotiations with two museums, was able to purchase both skeletal parts and unite in New York. This on the hind legs standing mounted skeleton is now one of the most important exhibits of the American Museum of Natural History.
Another fragmentary skeleton from the Dinosaur National Monument ( copy number ROM 3670 ) was rediscovered in the collection of the Royal Ontario Museum in Canada until 2007. This skeleton was excavated in the early 20th century by Earl Douglass and acquired in 1962 by the Royal Ontario Museum. Today it is one of the most important exhibits of the museum dar. Further findings were reported recently from South Dakota.