Barosaurus
| Barosaurus | ||||||||||||
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Barosaurus skeletal reconstruction |
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| Temporal occurrence | ||||||||||||
| Upper Jurassic ( Kimmeridgian to Tithonian ) | ||||||||||||
| 157.3 to 145 million years | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Barosaurus | ||||||||||||
| Marsh , 1890 | ||||||||||||
Barosaurus is a genus of sauropod dinosaur in the Diplodocidae family . She livedin North Americaduring the late Upper Jurassic ( Kimmeridgian to Tithonian ).
So far five incomplete skeletons have been described; However, skull bones have not yet been found. All finds come from the Morrison Formation , an important fossil deposit - a species described from Africa is now usually assigned to an independent genus, Tornieria . Barosaurus shared its habitat with a number of other sauropod species, including Apatosaurus , Diplodocus , Camarasaurus, and Brachiosaurus .
features
According to estimates, Barosaurus reached a length of 26 meters and a weight of 20 tons - making it about as big as the closely related Diplodocus .
It had a blueprint typical of Diplodocidae: the number of cervical vertebrae was increased because the anterior vertebrae were transformed into cervical vertebrae, which led to a particularly long neck. As with other Diplodocidae, the tail was also very long: the number of caudal vertebrae was probably increased to over 80, while the middle and rear caudal vertebrae were elongated. The front legs, on the other hand, were relatively short, as in other Diplodocidae. A skull has not yet been discovered. The closely related genera Diplodocus and Apatosaurus , however, show an elongated, low skull with forward-pointing, pin-like teeth that were limited to the foremost area of the jaws. It is possible that some skull finds attributed to Diplodocus actually belong to Barosaurus .
In contrast to the closely related Diplodocus , Barosaurus had relatively longer front legs and a longer neck and a shorter tail. While Diplodocus and Apatosaurus had 15 cervical vertebrae and 10 dorsal vertebrae, Barosaurus had at least one further dorsal vertebra converted into a cervical vertebra: Barosaurus only had 9 or 8 dorsal vertebrae, but possibly 16 cervical vertebrae. The cervical vertebrae were also extremely elongated and up to 50% longer than those of Diplodocus . The caudal vertebrae were shorter than those of Diplodocus ; the characteristic "double bars" formed by the chevron bones on the underside of the tail were a little less pronounced in Barosaurus than in Diplodocus .
In contrast to Apatosaurus , the skeletons of Barosaurus and Diplodocus were built lighter overall; in particular the front legs of the Apatosaurus were much more robust. In addition, the Apatosaurus cervical vertebrae were shorter and less light. The double bars formed by the chevron bones were much less pronounced in Apatosaurus than in Diplodocus and Barosaurus .
Systematics
Barosaurus belongs to the Diplodocidae , a family within the Diplodocoidea . Within the Diplodocidae, the genus is sometimes placed in a common subfamily with Diplodocus - the Diplodocinae. Apatosaurus , however, is placed in a different subfamily - the Apatosaurinae. The following is a recent example of a cladogram (simplified from Harris and Dotson, 2004):
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"Barosaurus" africanus
Currently, only one species of Barosaurus is generally recognized: Barosaurus lentus . Werner Janensch (1922) attributed a second species to the genus Barosaurus ( Barosaurus africanus ), based on finds from Tendaguru in East Africa. This species was first described in 1908 by Eberhard Fraas as one of two species of the genus Gigantosaurus . However, since the name Gigantosaurus was already given to a sauropod from England, the genus was later renamed Tornieria . Whether this African species is actually a second Barosaurus species ( Barosaurus africanus ), or whether it must be ascribed to an independent, closely related genus as Tornieria africana , is still controversial.
Paleoecology
The Morrison formation has a diverse sauropod fauna: Barosaurus shared its habitat mainly with Diplodocus and Apatosaurus ; Brachiosaurus , Haplocanthosaurus and Suuwassea were less common . For a long time, Barosaurus was considered a rare sauropod in the Morrison fauna. It was only recently that it became clear that many of the fossils described as Diplodocus were actually Barosaurus attributable.
Finds, research history and naming
The first skeleton was discovered by Mrs. ER Ellerman in the Black Hills of South Dakota and partially recovered in 1889 by paleontologists Othniel Charles Marsh and John Bell Hatcher . Marsh and Hatcher were only able to recover parts of the tail, which is why Marsh commissioned the discoverer to protect the remaining skeleton from fossil collectors. It was not until nine years later (1898) that Marsh commissioned George Wieland to excavate the remaining skeleton. As Wieland discovered, the discoverer had died three years ago and fossil collectors had already stolen parts of the skeleton. Nevertheless, within two months, Wieland was able to recover additional caudal vertebrae, parts of the sacrum, back vertebrae, four cervical vertebrae, parts of the right pubic bone , ribs and a sternum.
Marsh published a brief description as early as 1890, a year after the skeleton was discovered, based on the caudal vertebrae collected by him and Hatcher ( holotype , copy number YPM 429 ). He stated that the caudal vertebrae were similar to Diplodocus ', but were shorter overall and showed deep pleurocoels (lateral cavities) and less pronounced chevron bones . Marsh named the new genus Barosaurus ("heavy lizard", from gr. Barys - "heavy"; gr. Sauros - "lizard"), which should indicate the enormous size of this animal. In a later publication (1896) he attributed Barosaurus to the Atlantosauridae - it was not until 1898 that Marsh recognized this genus as a relative of Diplodocus and classified it within the Diplodocidae. In his last publication (1899) before his death, he named a second species, Barosaurus affinis , based on two relatively small metacarpal bones. Today Barosaurus affinis is considered identical to the type species Barosaurus lentus . A complete description of the prepared Barosaurus skeleton followed in 1919 by RS Lull.
Other Barosaurus finds were discovered in what is now the Dinosaur National Monument , an extremely rich fossil site near Jensen , Utah . Earl Douglass discovered some very long cervical vertebrae near a well-preserved Diplodocus skeleton in 1912 . At first he thought these vertebrae were part of the Diplodocus skeleton - it was only after he had completely exposed the vertebrae that he realized their enormous length and speculated that they might actually belong to Barosaurus . It later emerged that these vertebrae are likely part of another, fragmentary Barosaurus skeleton (copy number ROM 3670) that was initially ascribed to Diplodocus . Another skeleton (CM 11984) was discovered by Douglass in 1918. Douglass was unsure whether this skeleton belonged to Barosaurus or to Brachysaurus ( Brachiosaurus ). It was only prepared in the 1980s and is still in a find position in a stone wall displayed in the Dinosaur National Monument.
The most famous Barosaurus skeleton (copy number AMNH 6341) is on display today in the American Museum of Natural History in New York. This specimen , initially attributed to Diplodocus , was also uncovered by Douglass in the Dinosaur National Monument. At the same time, Gilmore from the National Museum of Natural History ( Washington, DC ) excavated a Diplodocus skeleton in the same site , which he intended to mount in Washington. This Diplodocus skeleton (copy number USNM 10845) was very incomplete, which is why Douglass Gilmore gave most of the cervical vertebrae to complete the skeleton. It was not until the preparation in Washington that it was noticed that the vertebrae were actually Barosaurus vertebrae, which are useless for completing the Diplodocus skeleton. The Barosaurus skeleton was thus divided into two different museums. In 1929 Barnum Brown of the American Museum of Natural History started negotiations with both museums, was able to acquire both skeletal parts and unite them in New York. This skeleton, mounted on its hind legs, is one of the most important exhibits in the American Museum of Natural History today.
Another, fragmentary skeleton from the Dinosaur National Monument (copy number ROM 3670) was not rediscovered until 2007 in the collection of the Royal Ontario Museum in Canada. This skeleton was excavated by Earl Douglass in the early 20th century and acquired by the Royal Ontario Museum in 1962. Today it is one of the most important exhibits in the museum. More recent finds have been reported from South Dakota. In 2016 and 2017, finds of vertebrae were published that were assigned to a juvenile Barosaurus due to the not yet fully closed growth plates of the bones and at the same time underline the existence of air-filled areas in the bones of the animals due to specific features.
Individual evidence
- ^ Gregory S. Paul : The Princeton Field Guide To Dinosaurs. Princeton University Press, Princeton NJ et al. 2010, ISBN 978-0-691-13720-9 , p. 189, online ( memento of the original from July 13, 2015 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. .
- ^ Dougal Dixon : The World Encyclopedia of Dinosaurs & Prehistoric Creatures. Lorenz, London 2008, ISBN 978-0-7548-1730-7 , p. 219.
- ↑ a b c d e f g h i j John S. McIntosh: The Genus Barosaurus (Marsh). In: Virginia Tidwell, Kenneth Carpenter (Eds.): Thunder-Lizards. The Sauropodomorph Dinosaurs. Indiana University Press, Bloomington IN et al. 2005, ISBN 0-253-34542-1 , pp. 38-77.
- ^ Frank Seebacher: A new method to calculate allometric length-mass relationships of dinosaurs. In: Journal of Vertebrate Paleontology. Vol. 21, No. 1, 2001, ISSN 0272-4634 , pp. 51-60, doi : 10.1671 / 0272-4634 (2001) 021 [0051: ANMTCA] 2.0.CO; 2 .
- ↑ Michael P. Taylor, Darren Naish: The phylogenetic taxonomy of Diplodocoidea (Dinosauria: Sauropoda). In: PaleoBios. Vol. 25, No. 2, 2005, ISSN 0031-0298 , pp. 1-7.
- ↑ Jerald D. Harris, Peter Dodson : A new diplodocoid sauropod dinosaur from the Upper Jurassic Morrison Formation of Montana, USA. In: Acta Palaeontologica Polonica. Vol. 49, No. 2, 2004, ISSN 0567-7920 , pp. 197-210, online .
- ↑ Ben Creisler: Dinosauria Translation and Pronunciation Guide ( Memento of October 13, 2011 in the Internet Archive )
- ↑ Massive Barosaurus skeleton discovered at the ROM. Royal Ontario Museum , November 13, 2007, archived from the original on June 14, 2011 ; Retrieved August 12, 2014 .
- ^ John R. Foster: Sauropod dinosaurs of the Morrison Formation (Upper Jurassic), Black Hills, South Dakota and Wyoming. In: University of Wyoming, Department of Geology. Contributions to Geology. Vol. 31, No. 1, 1996, ISSN 0010-7980 , pp. 1-25.
- ↑ a b Keegan M. Melstrom, Michael D. D'Emic, Daniel Chure, Jeffrey A. Wilson: A Juvenile Sauropod Dinosaur from the Late Jurassic of Utah, USA, Presents Further Evidence of an Avian Style Air Sac system. Journal of Vertebrate Paleontology 36 (4), 2016. doi : 10.1080 / 02724634.2016.1111898 .
- ↑ a b Gina M. Hanik, Matthew C. Lamanna, John A. Whitlock: A Juvenile Specimen of Barosaurus Marsh, 1890 (Sauropoda: Diplodocidae) from the Upper Jurassic Morrison Formation of Dinosaur National Monument, Utah, USA. Annals of Carnegie Museum 84 (3), June 2017; Pp. 253-263. doi : 10.2992 / 007.084.0301 .
