Barosaurus

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Barosaurus
Temporal range:
Ma
↓
Mounted skeleton in rearing posture with a juvenile
Kaatedocus siberi, American Museum of Natural History
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: †Sauropodomorpha
Clade: †Sauropoda
Superfamily: †Diplodocoidea
Family: †Diplodocidae
Genus: †Barosaurus
Marsh, 1890
Species:
†B. lentus
Binomial name
†Barosaurus lentus
Marsh, 1890

Barosaurus (

Period of Utah and South Dakota. It is present in stratigraphic zones 2–5.[1]

The composite term Barosaurus comes from the Greek words barys (βαρυς) meaning "heavy" and sauros (σαυρος) meaning "lizard", thus "heavy lizard".

Description

Life reconstruction of an individual rearing up to defend itself against a pair of Allosaurus

Barosaurus was an enormous animal, with some adults measuring about 25–27 m (82–89 ft) in length and weighing about 12–20 

Supersaurus vivianae,[5] may actually belong to Barosaurus. He suggested that, interpreted as belonging to Barosaurus, the vertebra suggests an animal that was 48 m (157 ft) long and around 66 t (73 short tons) in weight making it one of the largest known dinosaurs, with a neck length of at least 15 m (49 ft).[6] In 2020 Molina-Perez and Larramendi estimated it to be slightly smaller at 45 m (148 ft) and 60 t (66 short tons).[7] However, research presented by Brian Curtice at the Society of Vertebrate Paleontology conference has supported the previous interpretation of BYU 9024 as a Supersaurus vertebra.[8] Barosaurus was differently proportioned than its close relative Diplodocus, with a longer neck and shorter tail, but was about the same length overall. It was longer than Apatosaurus, but its skeleton was less robust.[9]

Sauropod skulls are rarely preserved, and scientists have yet to discover a Barosaurus skull. Related diplodocids like Apatosaurus and Diplodocus had long, low skulls with peg-like teeth confined to the front of the jaws.[10]

Size comparison

Most of the distinguishing skeletal features of Barosaurus were in the

chevron bones lining the underside of the tail were forked and had a prominent forward spike, much like the closely related Diplodocus. The tail probably ended in a long whiplash, much like Apatosaurus, Diplodocus and other diplodocids, some of which had up to 80 tail vertebrae.[9]

The limb bones of Barosaurus were virtually indistinguishable from those of Diplodocus.

metacarpals were more slender than those of Diplodocus.[11] Barosaurus feet have never been discovered, but like other sauropods, it would have been digitigrade, with all four feet each bearing five small toes. A large claw adorned the inside digit on the manus (forefoot) while smaller claws tipped the inside three digits of the pes (hindfoot).[9][10]

Classification and systematics

Barosaurus is a member of the sauropod family Diplodocidae, and sometimes placed with Diplodocus in the subfamily Diplodocinae.[5] Diplodocids are characterized by long tails with over 70 vertebrae, shorter forelimbs than other sauropods, and numerous features of the skull. Diplodocines like Barosaurus and Diplodocus have slenderer builds and longer necks and tails than apatosaurines, the other subfamily of diplodocids.[9][10][5]

Below is a cladogram of Diplodocinae after Tschopp, Mateus, and Benson (2015).[12]

Gordo, Royal Ontario Museum
skeleton, Toronto
Diplodocinae

Unnamed species

Tornieria africana

Supersaurus lourinhanensis

Supersaurus vivianae

Leinkupal laticauda

Galeamopus hayi

Diplodocus carnegii

Diplodocus hallorum

Kaatedocus siberi

Barosaurus lentus

The

Tendaguru Beds of Tanzania in eastern Africa have also been classified as diplodocines.[15][16] With its elongated neck vertebrae, Tornieria may have been particularly closely related to Barosaurus.[15] The other subfamily of diplodocids is Apatosaurinae, which includes Apatosaurus and Supersaurus.[5] The early genus Suuwassea is considered by some to be an apatosaurine,[5] while others regard it as a basal member of the superfamily Diplodocoidea.[17] Diplodocid fossils are found in North America, Europe, and Africa. More distantly related within Diplodocoidea are the families Dicraeosauridae and Rebbachisauridae, found only on the southern continents.[10]

Discovery, naming, and history

One of the original tail vertebrae in multiple views

The first Barosaurus remains were discovered in the

junior synonym of B. lentus.[9][10][22]

After the turn of the 20th century, Pittsburgh's Carnegie Museum of Natural History sent fossil hunter Earl Douglass to Utah to excavate the Carnegie Quarry in the area now known as Dinosaur National Monument. Four neck vertebrae, each 1 meter (3 feet) long, were collected in 1912 near a specimen of Diplodocus, but a few years later, William Jacob Holland realized they belonged to a different species.[9] Meanwhile, the type specimen of Barosaurus had finally been prepared at Yale in the winter of 1917 and was fully described by Richard Swann Lull in 1919.[22] Based on Lull's description, Holland referred the vertebrae (CM 1198), along with a second partial skeleton found by Douglass in 1918 (CM 11984), to Barosaurus. This second Carnegie specimen remains in the rock wall at Dinosaur National Monument and was not fully prepared until the 1980s.[9]

Allosaurus fragilis, American Museum of Natural History

The most complete specimen of Barosaurus lentus was excavated from the Carnegie Quarry in 1923 by Douglass, now working for the

Kaatedocus siberi[12]) from an attacking Allosaurus fragilis.[9]

More recently, more vertebrae and a pelvis were recovered in South Dakota. This material (SDSM 25210 and 25331) is stored in the collection of the South Dakota School of Mines and Technology in Rapid City.[11]

Darren Naish has noted a common error in books of the late 20th century to depict Barosaurus as a kind of brachiosaur-like short tailed sauropod with raphes on its neck and body, and often curving the upper half of its neck downwards into a U-shape, citing it as an example of a Palaeoart meme.[23][24] This originated with a drawing by Robert Bakker in a 1968 article, in which two Barosaurus appeared to have short tails due to a mix of foreshortening and one obscuring the other.

In 2007, paleontologist David Evans was flying to the U.S. Badlands when he discovered reference to a Barosaurus skeleton (ROM 3670) in the collection of the Royal Ontario Museum in Toronto, where he had recently become a curator. Earl Douglass had excavated this specimen at the Carnegie Quarry in the early 20th century; the ROM acquired it in a 1962 trade with the Carnegie Museum. The specimen was never exhibited and remained in storage until its rediscovery by David Evans 45 years later. He returned to Toronto and searched the storage areas and found many fragments, large and small, of the skeleton. It is now a centrepiece of the ROM's dinosaur exhibit, in the James and Louise Temerty Galleries of the Age of Dinosaurs.[25] At almost 27.5 meters (90 feet) long, the specimen is the largest dinosaur ever to be mounted in Canada.[26] The specimen is about 40% complete. As a skull of Barosaurus has never been found, the ROM specimen wears the head of a Diplodocus.[27] Each bone is mounted on a separate armature so that it can be removed from the skeleton for study and then replaced without disturbing the rest of the skeleton. (See video "Dino Workshop" at reference.)[28] In the rush to put the dinosaur on exhibit within ten weeks of its delivery to Research Casting International in 2500 pieces, not all of the skeletal fragments were mounted. In addition, more bones labeled ROM 3670 are still being found in storage. In future, more may be added to the specimen and it may turn out to be the most complete known.' (See video "Dino Assembly" at reference.)[28] The ROM specimen is nicknamed "Gordo" after Gordon Edmunds, the museum curator who arranged for the skeleton to be brought to the ROM, and who had hoped to display it fully but was unable to.[26][29][30] John McIntosh believes that the ROM's skeleton is the same individual represented by four neck vertebrae labeled "CM 1198" in the collection of the Carnegie Museum.[9]

Discoveries in Africa

In 1907,

Kadsi Formation in Zimbabwe in 1987.[36] However, this material is poorly preserved and fragmentary and was not adequately diagnosed as such, and so its referral to Barosaurus is doubtful. It may represent Tornieria.[37]

Paleobiology

Feeding

Skull cast, Natural History Museum of Utah

The structure of the cervical vertebrae of Barosaurus allowed for a significant degree of lateral flexibility in the neck, but restricted vertical flexibility. This suggests a different feeding style for this genus when compared to other diplodocids.[38] Barosaurus swept its neck in long arcs at ground level when feeding, which resembled the strategy that was first proposed by John Martin in 1987.[39] The restriction in vertical flexibility suggests that Barosaurus did not primarily feed on vegetation that was high off the ground.

Paleoecology

Barosaurus remains are limited to the

Period,[40] or approximately 155 to 148 million years ago.[41] Barosaurus fossils are found in late Kimmeridgian to early Tithonian sediments,[12] around 150 million years old.[40]

Skull possibly belonging to Barosaurus (specimen CM 11255)

The Morrison Formation was deposited in

Tendaguru Formation in Tanzania. In 1877 this formation became the center of the Bone Wars, a fossil-collecting rivalry between early paleontologists Othniel Charles Marsh and Edward Drinker Cope
.

The Morrison Formation records an environment and time dominated by gigantic sauropod dinosaurs such as

fungi, mosses, horsetails, cycads, ginkgoes, and several families of conifers. Vegetation varied from river-lining forests of tree ferns, and ferns (gallery forests), to fern savannas with occasional trees such as the Araucaria-like conifer Brachyphyllum.[48]

Assistant Curator David Evans mounted the ROM specimen conservatively, with a relatively low head to give the dinosaur moderate blood pressure.[27] The extremely long neck, 10 meters (30 feet) may have developed to enable Barosaurus to feed over a wide area without moving around; it may also have enabled the dinosaurs to radiate excess body heat. Evans suggests that sexual selection might have favored those with longer necks. (See video "Neck Impossible" at reference.)[28]

References

  1. ^ Foster, J. (2007). "Appendix." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. pp. 327-329.
  2. S2CID 53446536
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  3. PMID 24204747
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  4. ^ Paul, G.S., 2016, The Princeton Field Guide to Dinosaurs 2nd edition, Princeton University Press p. 213
  5. ^ a b c d e Lovelace, David M.; Hartman, Scott A.; Wahl, William R. (2007). "Morphology of a specimen of Supersaurus (Dinosauria, Sauropoda) from the Morrison Formation of Wyoming, and a re-evaluation of diplodocid phylogeny" (PDF). Arquivos do Museu Nacional, Rio de Janeiro. 65 (4): 527–544. Archived from the original (PDF) on October 6, 2011. Retrieved November 11, 2010.
  6. ^ "The size of the BYU 9024 animal". svpow.com. June 16, 2019. Archived from the original on April 16, 2022.
  7. ISBN 9780691190693
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  8. ^ Curtice, Brian (November 1–5, 2021). "New Dry Mesa Dinosaur Quarry Supersaurus vivianae (Jensen 1985) axial elements provide additional insight into its phylogenetic relationships and size, suggesting an animal that exceeded 39 meters in length" (PDF). The Society of Vertebrate Paleontology Virtual Meeting conference Program. p. 92. Archived (PDF) from the original on October 8, 2022.
  9. ^
    ISBN 978-0-253-34542-4
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  10. ^
    ISBN 978-0-520-24209-8
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  11. ^ a b Foster, John R. (1996). "Sauropod dinosaurs of the Morrison Formation (Upper Jurassic), Black Hills, South Dakota and Wyoming". Contributions to Geology, University of Wyoming. 31 (1): 1–25. Archived from the original on June 21, 2010.
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  14. ^ Lucas, Spencer G.; Spielmann, Justin A.; Rinehart, Larry A.; Heckert, Andrew B.; Herne, Matthew C.; Hunt, Adrian P.; Foster, John R.; Sullivan, Robert M. (2006). "Taxonomic status of Seismosaurus hallorum, a Late Jurassic sauropod dinosaur from New Mexico". In Foster, John R.; Lucas, Spencer G. (eds.). Paleontology and Geology of the Upper Jurassic Morrison Formation. New Mexico Museum of Natural History and Science Bulletin 36: 149-161.
  15. ^
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  18. S2CID 131403178
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  19. ^ Marsh, O.C. (1896). "The dinosaurs of North America". United States Geological Survey, 16th Annual Report, 1894-95. 55: 133–244.
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  21. doi:10.2475/ajs.s4-7.39.227
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  22. ^ a b Lull, Richard S. (1919). "The sauropod dinosaur Barosaurus Marsh: redescription of the type specimens in the Peabody Museum, Yale University". Memoirs of the Connecticut Academy of Arts and Sciences. 6: 1–42.
  23. ^ Naish, Darren (February 10, 2017). "Palaeoart Memes and the Unspoken Status Quo in Palaeontological Popularization". Scientific American. Retrieved April 25, 2020.
  24. doi:10.26879/145
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  25. ^ "Massive Barosaurus skeleton discovered at the ROM" (Press release). Royal Ontario Museum. November 13, 2007. Retrieved February 25, 2009.
  26. ^ a b Royal Ontario Museum. ROM Channel: Constructing the Barosaurus. Added 2012-08-28. Accessed 2012-12-11.
  27. ^ a b National Geographic, Museum Secrets, Episode 3: Royal Ontario Museum, Segment "Lost Dinosaur" Archived July 30, 2021, at the Wayback Machine. Broadcast December 10, 2012.
  28. ^ a b c National Geographic, Museum Secrets, Episode 3: Royal Ontario Museum, Segment "Lost Dinosaur". Video clips. Archived July 30, 2021, at the Wayback Machine. Broadcast December 10, 2012.
  29. ^ Anthony Reinhardt. A monster task - putting Gordo together, The Globe and Mail, November 29, 2007.
  30. ^ Zain Ahmed. Gordo the Barosaurus. Atlas Obscura. March 15, 2021.
  31. ^ Fraas, Eberhard (1908). "Ostafrikanische Dinosaurier". Palaeontographica. 55: 105–144.
  32. ^
    Seeley, Harry G.
    (1869). Index to the fossil remains of Aves, Ornithosauria and Reptilia, from the Secondary system of strata arranged in the Woodwardian Museum of the University of Cambridge. Cambridge: Deighton, Bell and Co. pp. 143pp.
  33. ^ Sternfeld, Richard (1911). "Zur Nomenklatur der Gattung Gigantosaurus Fraas". Sitzungsberichte der Gesellschaft Naturforschender Freunde zu Berlin. 1911: 398.
  34. ^ Janensch, Werner (1922). "Das Handskelett von Gigantosaurus robustus und Brachiosaurus brancai aus den Tendaguru-Schichten Deutsch-Ostafrikas". Centralblatt für Mineralogie, Geologie und Paläontologie. 1922: 464–480.
  35. ^ Wild, Rupert (1991). "Janenschia n. g. robusta (E. Fraas 1908) pro Tornieria robusta (E. Fraas 1908) (Reptilia, Saurischia, Sauropodomorpha)". Stuttgarter Beiträge zur Naturkunde. Serie B (Geologie und Paläontologie). 173: 1–4.
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  38. doi:10.7287/peerj.preprints.67v1
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  39. ^ Martin, John. 1987. Mobility and feeding of Cetiosaurus (Saurischia, Sauropoda) – why the long neck? pp. 154–159 in P. J. Currie and E. H. Koster (eds), Fourth Symposium on Mesozoic Terrestrial Ecosystems, Short Papers. Boxtree Books, Drumheller (Alberta). 239 pages.
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  41. Kirkland, James I. (eds.). The Upper Jurassic Morrison Formation: An Interdisciplinary Study. Modern Geology 22 (1-4): 235-260. Archived from the original
    (PDF) on August 24, 2007. Retrieved May 10, 2009.
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  44. Kirkland, James I.
    (eds.). The Upper Jurassic Morrison Formation: An Interdisciplinary Study. Modern Geology 22 (1-4): 283-296.
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  47. ^ Foster, John R. (2003). Paleoecological Analysis of the Vertebrate Fauna of the Morrison Formation (Upper Jurassic), Rocky Mountain Region, U.S.A. New Mexico Museum of Natural History and Science Bulletin, 23. Albuquerque, New Mexico: New Mexico Museum of Natural History and Science. p. 29.
  48. ^ Carpenter, Kenneth (2006). "Biggest of the big: a critical re-evaluation of the mega-sauropod Amphicoelias fragillimus". In Foster, John R.; Lucas, Spencer G. (eds.). Paleontology and Geology of the Upper Jurassic Morrison Formation. New Mexico Museum of Natural History and Science Bulletin, 36. Albuquerque, New Mexico: New Mexico Museum of Natural History and Science. pp. 131–138.

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