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Brachiosaurus

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Brachiosaurus was a sauropod that lived in the late Jurassic. Brachiosaurus had a proportionally long neck, small skull, and large overall size, all of which are typical for sauropods. However, the proportions of Brachiosaurus are unlike most sauropods. It was an extremely tall dinosaur and as a member of the brachiosaur group was one of few sauropods that could actually have their necks vertical. It also had very long front legs that give it its name, which means "arm lizard". Its tail was shorter compared to its body than most sauropod's, but it could still be used to deliver a nasty lash to predators.

Brachiosaurus is the namesake genus of the family Brachiosauridae, which includes a handful of other similar sauropods. Much of what is known by laypeople about Brachiosaurus is in fact based on Giraffatitan brancai, a species of brachiosaurid dinosaur from the Tendaguru Formation of Tanzania that was originally described by German paleontologist Werner Janensch as a species of Brachiosaurus. Recent research shows that the differences between the type species of Brachiosaurus and the Tendaguru material are significant enough that the African material should be placed in a separate genus. Several other potential species of Brachiosaurus have been described from Africa and Europe, but none of them are thought to belong to Brachiosaurus at this time.

Description

Like all sauropod dinosaurs, Brachiosaurus was a quadrupedal animal with a small skull, a long neck, a large trunk with a high-ellipsoid cross section, a long, muscular tail and slender, columnar limbs.[1] The skull had a strong, wide snout and thick jaw bones, with spoon–shaped teeth. As in Giraffatitan, there was an arch of bone over the snout and in front of the eyes that encircled the nasal opening, although this arch was not as large as in its relative.[2] Large air sacs connected to the lung system were present in the neck and trunk, invading the vertebrae and ribs, greatly reducing the overall density.[3][4] Unusually for a sauropod, the forelimbs were longer than the hind limbs. The upper arm bone was lightly built for its size,[5] measuring (6.7 ft) in length in the type specimen.[6] The thigh bone of the type specimen was only 6.7 ft long.[6] Unlike other sauropods, Brachiosaurus appears to have been slightly sprawled at the shoulder joint,[5] and the ribcage was unusually deep.[6] This led to the trunk being inclined, with the front much higher than the hips, and the neck exiting the trunk at a steep angle. Overall, this shape resembles a giraffe more than any other living animal.[7]

Size

Since "Brachiosaurus" brancai (Giraffatitan) is known from much more complete remains than B. altithorax, most size estimates for Brachiosaurus are actually for the African form. Over the years, the mass of B. altithorax has been estimated between 30 and 50 tons.[5][7][8] In the first and last cases, the authors also provided estimates for Giraffatitan, and found that genus to be somewhat lighter (31.5 metirc tons for Paul [1988][7] and 23.3 metric tons for Taylor [2009][5]). The length of Brachiosaurus has been estimated at 85 ft.[9] This dinosaur was bigger than Apatosaurus but smaller than Diplodocus and Argentinosaurus.

Classification

Brachiosaurus is the namesake genus of Brachiosauridae.[10] Through the years some sauropods have been assigned to Brachiosauridae, such as Astrodon, Bothriospondylus, Dinodocus, Pelorosaurus, Pleurocoelus, and Ultrasaurus,[11] but most of these are now viewed as dubious or of uncertain placement.[1] A phylogenetic analysis of sauropods published in the description of Abydosaurus found that genus to form a clade with Brachiosaurus and Giraffatitan (included in Brachiosaurus).[12] A more recent analysis focused on possible Asian brachiosaurid material found a clade including Abydosaurus, Brachiosaurus, Cedarosaurus, Giraffatitan, and Paluxysaurus, but not Qiaowanlong, the claimed Asian brachiosaurid.[13] Related genera include Lusotitan and Sauroposeidon.[1] Brachiosauridae is placed at the base of Titanosauriformes, a group of sauropods that also includes the titanosaurs.[13]

According to the revised diagnosis by Taylor Brachiosaurus altithorax is diagnosed by a plethora of characters, many to be found on the back vertebrae.[5] Among the characters playing it in the family Brachiosauridae are the upper arm bone being at least close to as long as the thigh bone), and a very flattened femur shaft (ratio ≥1.85).[5]

Species

Brachiosaurus altithorax

The holotype of both the genus Brachiosaurus and the species B. altithorax, consists of the right upper arm bone, the right thigh bone, the right hip bone, the right shoulder bone, the fused vertebrae of the hip, the last seven trunk and two tail vertebrae, and a number of ribs.[5][6][14] Riggs described the coracoid as from the left side of the body,.[6][10][14] Riggs described the shoulder bone as from the left side of the body,[5][6][10][14] ur". Science 13 (327): 549–550. doi:10.1126/science.13.327.549-a. PMID 17801098.</ref> but restudy has shown it to be a right shoulder bone.

Other assigned species

  • "B." atalaiensis: First described by de Lapparent and Zbyszewski,[15] in 2003, it was placed in its own genus Lusotitan by Antunes and Mateus.[16]
  • B." brancai: Found in Africa by Janensch in the Tendaguru site [17] It includes, among other bones, several trunk vertebrae, both shoulder bones, both breastbones, both upper arm bones, both lower arm bones, a right hand, a partial left hand, both hip bones and the right thigh bone. A re-assessment of the relation between the African and American brachiosaur material shows that a separate generic name is warranted for the former, whcih means that it now is considered to belong to Giraffatitan.[5][7]
  • "B." fraasi: built by Janensch in 1914, but later synonymized with "B." brancai;[18] this material now belongs to Giraffatitan.[5]
  • "B." nougaredi: This species is known from incomplete remains found in the Sahara. de Lapparent, who described and named the material in 1960, said it lived in the Late Jurassic [19] but more recent review assigns it to the early Cretaceous. Upchurch, Barrett and Dodson (2004) doubted its assignment to Brachiosaurus, and listed it as an unnamed brachiosaurid.[1] The hip vertebrae is of notable size, with a length of 51 in for four vertebrae compared to 37 in for five vertebrae in B. altithorax.[19]

Separation from Giraffatitan

When describing the brachiosaurid material from Tendaguru in 1914, Janensch listed a number of differences and similarities between them and B. altithorax.[17] In three more publications in 1929,[18] 1950 [20] and 1961[21] Janensch compared the two species in more detail, listing 13 supposed shared characters.[5] Of these, however, only four appear to be valid, while six pertain to more inclusive groups than Brachiosauridae, and the rest are either hard to judge or refer to material that is not Brachiosaurus.[5]

In 1988, Gregory Paul published a new rebuilding of the skeleton of "B." brancai, pointing out a number of differences in proportion between it and B. altithorax. Chief among them is a difference in the way the trunk vertebrae vary: they are quite uniform in B. altithorax, but vary widely in the African material. Paul thought that the limb and girdle elements of both species were very similar, and so he suggested to separate them not at genus, but only at subgenus level.[7]

Giraffatitan was raised to genus level by Olshevsky without comment.[22] A detailed study of all material, including the limb and girdle bones, by Michael Taylor in 2009 found that there are significant differences between Brachiosaurus altithorax and the Tendaguru material in all elements known from both species. Taylor found 26 distinct osteological (bone-based) characters, a larger difference than that between, e.g., Diplodocus and Barosaurus, and therefore argued that the African material should be placed in its own genus, Giraffatitan, as G. brancai.[5] An important difference between the two genera is the overall body shape, with Brachiosaurus having a 23% longer dorsal (trunk) vertebrate series and a 20 to 25% longer and also taller tail.[5]

History of discovery

The genus Brachiosaurus, and type species B. altithorax, are based on a partial postcranial skeleton from Fruita, in the valley of the Colorado River of western Colorado.[23] This specimen was collected from rocks of the Brushy Basin Member of the Morrison Formation[24] in 1900 by Elmer S. Riggs and his crew from the Field Columbian Museum (now the Field Museum of Natural History) of Chicago.[6] Riggs and company were working in the area as a result of favorable correspondence between Riggs and S. M. Bradbury, a dentist in nearby Grand Junction. In 1899 Riggs had sent inquiries to rural locations in the western United States concerning fossil finds, and Bradbury, an amateur collector himself, reported that dinosaur bones had been collected in the area since 1885.[23] The locality, Riggs Quarry 13, was found on a small hill later known as Riggs Hill; it is marked by a plaque. Additional Brachiosaurus fossils are reported on Riggs Hill, but other fossil finds on the hill have been vandalized.[25][25] Riggs published a short report in 1901, noting the unusual length of the humerus compared to the femur and the extreme overall size and the resulting giraffe-like proportions, as well as the lesser development of the tail, but did not publish a name for the new dinosaur.[6][14] Riggs followed his 1903 publication that named Brachiosaurus altithorax[6] with a more detailed description in a monograph in 1904.[10]

The Fruita skeleton was not the first discovery of Brachiosaurus bones, although it was the first to be recognized as belonging to a new and distinct animal. In 1883, a sauropod skull was found near Garden Park, Colorado, at Felch Quarry 1, and was sent to Othniel Charles Marsh (of "Bone Wars" fame).[5] Marsh incorporated the skull into his skeletal restoration of "Brontosaurus" (now Apatosaurus).[5][26] It eventually became part of the collections of the National Museum of Natural History, as USNM 5730.[5] In the 1970s, when Jack McIntosh and David Berman were working on the issue of the true skull of Apatosaurus, they reevaluated the Garden Park skull as more similar to Camarasaurus.[27] It was described and recognized as a Brachiosaurus skull in 1998 by Kenneth Carpenter and Virginia Tidwell, intermediate in form between Camarasaurus and Giraffatitan brancai (then still considered to be B. brancai).[28] Because there are no overlapping parts between this skull and FMNH P 25107, it cannot be confidently assigned to a species,[5][28] so it is classified as Brachiosaurus sp.[28]

Additional discoveries of Brachiosaurus material in North America have been uncommon and consist of a handful of bones. Material has been described from Colorado,[5][29][30][31] Oklahoma,[5][32] Utah,[5][29] and Wyoming,[5][8] and undescribed material has been mentioned from several other sites.[5][24] One of these specimens, a shoulder blade from Dry Mesa Quarry, Colorado, is one of the specimens at the center of the Supersaurus/Ultrasauros issue of the 1980s and 1990s. In 1985, James A. Jensen described disarticulated sauropod remains from the quarry as belonging to several taxa, including the new genera Supersaurus and Ultrasaurus,[33] the latter renamed Ultrasauros shortly thereafter because another sauropod already had the name.[22] Later study showed that the "ultrasaur" material mostly belonged to Supersaurus, although the shoulder blade did not. Because the holotype of Ultrasauros, a back vertebra, was one of the specimens that was actually from Supersaurus, the name Ultrasauros is a synonym of Supersaurus. The shoulder blade is now assigned to Brachiosaurus, but the species is uncertain.[5][30] In addition, the Dry Mesa "ultrasaur" was not as large as had been thought; the dimensions of the shoulder bone indicate that the animal was smaller than Riggs' original specimen of Brachiosaurus.[5]

Paleobiology

Feeding ecology

Brachiosaurus is thought to have been a high browser, feeding on foliage well above the ground. Even if it did not hold its neck near vertical, and instead had a straighter neck, its head height may still have been over 30 ft above the ground.[2][8] It probably fed mostly on foliage above 16 ft. This does not preclude the possibility that it also fed lower at times, between 9.8 to 16 ft up.[2] Its diet likely consisted of ginkgoes, conifers, tree ferns, and large cycads, with intake estimated at 440 to 480 pounds of plant matter daily.[2] However, more recent studies estimate that 530 pounds of plant matter would have been sufficient to feed a 70 metric ton sauropod,[34] so Brachiosaurus may have required only about 260 pounds of fodder a day. Brachiosaur feeding involved simple up–and–down jaw motion. The teeth were arranged to shear material as they closed, and were probably used to crop and/or nip vegetation.[35]

Neck position

In contrast to most other sauropods, brachiosaurids had a sloped back, due to their long front legs. So, if the neck exited the body in a straight line, it already pointed up.[5][36][37][38]

Shorty

Shorty, the Brachiosaurus.

Brachiosaurus in The Land Before Time

It is one of the many species known as a longneck to Land Before Time dinosaurs. The only Brachiosaurus to have a name in The Land Before Time is Shorty, Littlefoot's adopted brother. Brachiosaurus first appeared in The Land Before Time II: The Great Valley Adventure during the opening narration and appear various times afterwards. A herd of them appears in Grandpa Longneck's story of the Lone Dinosaur in The Land Before Time VI: The Secret of Saurus Rock, among them a boy who was almost eaten by the Meanest Sharptooth. He tried to stop the Lone Dinosaur leaving in the same way as Littlefoot does at the end of the movie. Most of the Brachiosaurus in the series look more like Giraffatitan. There have been several Brachiosaurus that have appeared in the franchise, with different color patterns this indicates that these are different species of the same genus. Brachiosaurus also appears in The Land Before Time III: The Time of the Great Giving in the beginning. Several Brachiosaurus are members of Bron's herd.

Gallery

Trivia

References

  1. ↑ 1.0 1.1 1.2 1.3 Upchurch, P., Barrett, P.M. & Dodson, P. (2004): "Sauropoda." Pp. 259-322 in Weishampel, D.B., Dodson, P. and Osmolska, H. (eds.): The Dinosauria, Second Edition. University of California Press, Berkeley. ISBN 9780520242098
  2. ↑ 2.0 2.1 2.2 2.3 Foster, J. (2007). "Brachiosaurus altithorax." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. pp. 205–208.
  3. ↑ Wedel, M.J. (2003). "Vertebral pneumaticity, air sacs, and the physiology of sauropod dinosaurs." Paleobiology 29:243-255.
  4. ↑ Wedel, M.J. (2003). "The evolution of vertebral pneumaticity in sauropod dinosaurs." Journal of Vertebrate Paleontology 23:344-357.
  5. ↑ 5.00 5.01 5.02 5.03 5.04 5.05 5.06 5.07 5.08 5.09 5.10 5.11 5.12 5.13 5.14 5.15 5.16 5.17 5.18 5.19 5.20 5.21 5.22 5.23 5.24 5.25 Taylor, M.P. (2009). "A re-evaluation of Brachiosaurus altithorax Riggs 1903 (Dinosauria, Sauropoda) and its generic separation from Giraffatitan brancai (Janensh 1914)." Journal of Vertebrate Paleontology, 29(3): 787-806.
  6. ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 Riggs, E.S. (1903). "Brachiosaurus altithorax, the largest known dinosaur." American Journal of Science (series 4) 15(88): 299-306.
  7. ↑ 7.0 7.1 7.2 7.3 7.4 Paul, G.S. (1988). "The brachiosaur giants of the Morrison and Tendaguru with a description of a new subgenus, Giraffatitan, and a comparison of the world's largest dinosaurs" (pdf). Hunteria 2 (3).
  8. ↑ 8.0 8.1 8.2 Foster, J.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.
  9. ↑ Holtz, T.R. Jr. (2008) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages Supplementary Information
  10. ↑ 10.0 10.1 10.2 10.3 Riggs, E.S. (1904). "Structure and relationships of opisthocoelian dinosaurs. Part II. The Brachiosauridae". Geological Series (Field Columbian Museum) 2 (6): 229–247.
  11. ↑ Lambert, David; and the Diagram Group (1990). "Brachiosaurids". The Dinosaur Data Book. New York: Avon Books. p. 142. ISBN 0-380-75896-3.
  12. ↑ Chure, D.; Britt, B.; Whitlock, J. A.; and Wilson, J. A. (2010). "First complete sauropod dinosaur skull from the Cretaceous of the Americas and the evolution of sauropod dentition". Naturwissenschaften 97 (4): 379–391. doi:10.1007/s00114-010-0650-6. PMC 2841758. PMID 20179896.
  13. ↑ 13.0 13.1 Ksepka, D. T.; and Norell, M. A. (2010). "The illusory evidence for Asian Brachiosauridae: new material of Erketu ellisoni and a phylogenetic appraisal of basal Titanosauriformes" (pdf). American Museum Novitates 3700: 1–27. doi:10.1206/3700.2.
  14. ↑ 14.0 14.1 14.2 14.3 Riggs, E.S. (1091). "The largest known dinosaur". Science 13 (327): 549–550. doi:10.1126/science.13.327.549-a. PMID 17801098.
  15. ↑ de Lapparent,A.F. & Zbyszewski, G. (1957). "Les dinosauriens du Portugal". Mémoire Service géologique Portugal 2:1–63.
  16. ↑ Antunes, M.; Mateus, O. (2003). "Dinosaurs of Portugal". Comptes rendus. Palévol 2 (1): 77–95. doi:10.1016/S1631-0683(03)00003-4.
  17. ↑ 17.0 17.1 Janensch, W. (1914). "Übersicht über der Wirbeltierfauna der Tendaguru-Schichten nebst einer kurzen Charakterisierung der neu aufgefuhrten Arten von Sauropoden." Archiv fur Biontologie, 3: 81–110.
  18. ↑ 18.0 18.1 Janensch, W. (1929). "Material und Formengehalt der Sauropoden in der Ausbeute der Tendaguru-Expedition." Palaeontographica (Suppl. 7) 2:1–34.
  19. ↑ 19.0 19.1 de Lapparent, A.F. (1960): "Les dinosauriens du "continental intercalaire" du Sahara central" ("The dinosaurs of the "continental intercalaire" of the central Sahara.") Mémoires de la Société Géologic de France, Nouvelle Série 88A vol.39(1-6):1-57. [in French; a translated version, by Matthew Carrano (pdf, no figures), is available through the Polyglot Paleontologist]
  20. ↑ Janensch, W. (1950). "Die Wirbelsäule von Brachiosaurus brancai." Palaeontographica (Suppl. 7) 3:27–93.
  21. ↑ Janensch, W. (1961). "Die Gliedmaßen und Gliedmaßengürtel der Sauropoden der Tendaguru-Schichten." Palaeontographica (Suppl. 7) 3:177–235.
  22. ↑ 22.0 22.1 Olshevsky, G. (1991). "A revision of the parainfraclass Archosauria Cope, 1869, excluding the advanced Crocodylia." Mesozoic Meanderings 2:1-196
  23. ↑ 23.0 23.1 Glut, D.F. (1997). "Brachiosaurus". Dinosaurs: The Encyclopedia. McFarland & Company. pp. 213–221. ISBN 0-89950-917-7.
  24. ↑ 24.0 24.1 Turner, C.E.; and Peterson, F. (1999). "Biostratigraphy of dinosaurs in the Upper Jurassic Morrison Formation of the Western Interior, USA". In Gillete, David D. (ed.). Vertebrate Paleontology in Utah. Miscellaneous Publication 99-1. Salt Lake City, Utah: Utah Geological Survey. pp. 77–114. ISBN 1-55791-634-9.
  25. ↑ 25.0 25.1 Chenoweth, W.L. (1987). "The Riggs Hill and Dinosaur Hill sites, Mesa County, Colorado". In Averett, W. R. (ed.). Paleontology and geology of the Dinosaur Triangle. Grand Junction, Colorado: Museum of Western Colorado. pp. 97–100. ISBN 9999790410.
  26. ↑ Marsh, O.C. (1891). "Restoration of Triceratops" (pdf). American Journal of Science 41 (244): 339–342.
  27. ↑ McIntosh, J.S.; and Berman, D.S. (1975). "Description of the palate and lower jaw of the sauropod dinosaur Diplodocus (Reptilia: Saurischia) with remarks on the nature of the skull of Apatosaurus". Journal of Paleontology 49 (1): 187–199.
  28. ↑ 28.0 28.1 28.2 Carpenter, K. and Tidwell, V. (1998). "Preliminary description of a Brachiosaurus skull from Felch Quarry 1, Garden Park, Colorado." Pp. 69–84 in: Carpenter, K., Chure, D. and Kirkland, J. (eds.), The Upper Jurassic Morrison Formation: An Interdisciplinary Study. Modern Geology, 23:1-4.
  29. ↑ 29.0 29.1 Jensen, J.A. (1987). "New brachiosaur material from the Late Jurassic of Utah and Colorado". The Great Basin Naturalist 47 (4): 592–608.
  30. ↑ 30.0 30.1 Curtice, B., Stadtman, K., and Curtice, L. (1996) "A re-assessment of Ultrasauros macintoshi (Jensen, 1985)." Pp. 87-95 in M. Morales (ed.), The Continental Jurassic: Transactions of the Continental Jurassic Symposium, Museum of Northern Arizona Bulletin number 60.
  31. ↑ Curtice, B.; and Stadtman, K. (2001). "The demise of Dystylosaurus edwini and a revision of Supersaurus vivianae". In McCord, R.D.; and Boaz, D. (eds.). Western Association of Vertebrate Paleontologists and Southwest Paleontological Symposium - Proceedings 2001. Mesa Southwest Museum Bulletin. 8. pp. 33–40.
  32. ↑ Bonnan, M.F.; and Wedel, M.J. (2004). "First occurrence of Brachiosaurus (Dinosauria, Sauropoda) from the Upper Jurassic Morrison Formation of Oklahoma". PaleoBios 24 (2): 12–21.
  33. ↑ Jensen, J.A. (1985). "Three new sauropod dinosaurs from the Upper Jurassic of Colorado". The Great Basin Naturalist 45 (4): 697–709.
  34. ↑ Hummel, J., Gee, C.T., Südekum, K.-H., Sander, P.M., Nogge, G. and Clauss, M. (2008). "In vitro digestibility of fern and gymnosperm foliage: implications for sauropod feeding ecology and diet selection". Proceedings of the Royal Society B, 275:1015-1021. doi:10.1098/rspb.2007.1728
  35. ↑ Barrett, Paul M.; and Upchurch, Paul (2005). "Sauropodomorph diversity through time". In Curry Rogers, Kristina A.; and Wilson, Jeffrey A.. The Sauropods: Evolution and Paleobiology. Berkeley, CA: University of California. pp. 125–156. ISBN 0-520-24623-3.
  36. ↑ Stevens, K. A. and Parrish, M. J. (1999). "Neck posture and feeding habits of two Jurassic sauropod dinosaurs." Science 284:798–800. doi:10.1126/science.284.5415.798
  37. ↑ Stevens, K. A. and Parrish, M. J. (2005). "Digital reconstructions of sauropod dinosaurs and implications for feeding." In The sauropods: evolution and paleobiology (eds. J. A.Wilson & K. Curry-Rogers), pp. 178–200. Berkeley, CA: University of California Press.
  38. ↑ Stevens, K. A. and Parrish, M. J. (2005). "Neck posture, dentition and feeding strategies in Jurassic sauropod dinosaurs." In Thunder Lizards: The Sauropodomorph dinosaurs" (eds. V. Tidwell & K. Carpenter). Bloomington, IN: Indiana University Press.


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