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Apatosaurus
Fossil range: Late Jurassic, 150 Ma
Current Apatosaurus excelsus skeletal mount at the American Museum of Natural History
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Sauropsida
Superorder: Dinosauria
Order: Saurischia
Suborder: Sauropodomorpha
Family: Diplodocidae
Genus: Apatosaurus
Marsh, 1877
Species
  • A. ajax Marsh, 1877 (type)
  • A. excelsus (Marsh, 1879) Riggs, 1903
  • A. louisae Holland, 1915
  • A. parvus (Peterson & Gilmore, 1902)
Synonyms
  • Brontosaurus Marsh, 1879
  • Elosaurus Peterson & Gilmore, 1902

Apatosaurus (pronounced /əˌpætɵˈsɔrəs/), including the popular but obsolete synonym Brontosaurus, is a genus of sauropod dinosaur that lived about 150 million years ago, during the Jurassic Period (Kimmeridgian and Tithonian ages). It was one of the largest land animals that ever existed, with an average length of 23 m (75 ft) and a mass of at least 23 metric tons (25 short tons). The composite term Apatosaurus comes from the Greek names apate (ἀπάτη)/apatelos (ἀπατηλός) meaning "deception"/"deceptive" and sauros (σαῦρος) meaning "lizard"; thus, "deceptive lizard". Othniel Charles Marsh gave it this name because he regarded the chevron bones as similar to those of some mosasaurs, members of a group of prehistoric marine lizards.

The cervical vertebrae were less elongated and more heavily constructed than those of Diplodocus and the bones of the leg were much stockier (despite being longer), implying a more robust animal. The tail was held above the ground during normal locomotion. Like most sauropods, Apatosaurus had only a single large claw on each forelimb, with the first three toes on the hind limb possessing claws.

Fossils of this animal have been found in Nine Mile Quarry and Bone Cabin Quarry in Wyoming and at sites in Colorado, Oklahoma and Utah, present in stratigraphic zones 2-6.[1]

Contents

Description

Life restoration of Apatosaurus

Apatosaurus was a tremendously large long-necked quadrupedal animal with a long whip-like tail. Its forelimbs were slightly shorter than its hindlimbs. One measurement places the total length of Apatosaurus at 26 meters (85 ft) and its weight at 24-32 tons, roughly the weight of four elephants.[2]

The skull was small in comparison with the size of the animal. The jaws were lined with spatulate teeth, which resembled chisels, suited to an herbivorous diet.

Classification and species

Apatosaurus is a member of the family Diplodocidae, a clade of gigantic sauropod dinosaurs. The family includes some of the longest creatures ever to walk the earth, including Diplodocus, Supersaurus, Suuwassea, and Barosaurus. Within the subfamily Apatosaurinae, Apatosaurus may be most closely related to Suuwassea, Supersaurus and Eobrontosaurus.[3][4][5]

Apatosaurus louisae skeleton, Carnegie Museum

In 1877, Othniel Charles Marsh published the name of the type species Apatosaurus ajax. He followed this in 1879 with a description of another, more complete specimen, which he thought represented a new genus and named Brontosaurus excelsus. In 1903, Elmer Riggs pointed out that Brontosaurus excelsus was in fact so similar to Apatosaurus ajax that it belonged in the same genus, which Riggs re-classified as Apatosaurus excelsus. According to the rules of the ICZN (which governs the scientific names of animals), the name Apatosaurus, having been published first, had priority as the official name; Brontosaurus was a junior synonym and therefore discarded from formal use.

 
   Diplodocidae   

 Apatosaurinae 

Suuwassea


      
   

Supersaurus   



Apatosaurus   




Diplodocinae

Barosaurus



Diplodocus





Cladogram of the Diplodocidae after Lovelace, Hartman, and Wahl, 2008.[5]

Apatosaurus ajax is the type species of the genus, and was named by the paleontologist Othniel Charles Marsh in 1877 after Ajax, the hero from Greek mythology. It is the holotype for the genus and two partial skeletons have been found, including part of a skull. Apatosaurus excelsus (originally Brontosaurus) was named by Marsh in 1879. It is known from six partial skeletons, including part of a skull, which have been found in the United States, in Colorado, Oklahoma, Utah, and Wyoming. Apatosaurus louisae was named by William Holland in 1915 in honor of Mrs. Louise Carnegie, wife of Andrew Carnegie who funded field research to find complete dinosaur skeletons in the American West. Apatosaurus louisae is known from one partial skeleton which was found in Colorado in the United States. Apatosaurus parvus was originally known as Elosaurus parvus, but was reclassified as a species of Apatosaurus in 1994.[6] This synonymy was upheld in 2004.[7]

Apatosaurus yahnahpin was named by Filla and Redman in 1994. Robert T. Bakker made A. yahnahpin the type species of a new genus, Eobrontosaurus in 1998,[8] so it is now properly Eobrontosaurus yahnahpin. One partial skeleton has been found in Wyoming. It has been argued that Eobrontosaurus belongs within Camarasaurus,[9] although this has been questioned.[10][2]

History

1896 diagram of the Apatosaurus excelsus (then Brontosaurus) skeleton by O.C. Marsh. The head is based on material now assigned to Brachiosaurus sp.[11]

Othniel Charles Marsh, a Professor of Paleontology at Yale University, described and named an incomplete (and juvenile) skeleton of Apatosaurus ajax in 1877. Two years later, Marsh announced the discovery of a larger and more complete specimen at Como Bluff Wyoming — which, because of discrepancies including the size difference, Marsh incorrectly identified as belonging to an entirely new genus and species. He dubbed the new species Brontosaurus excelsus, meaning "thunder lizard", from the Greek brontē/βροντη meaning 'thunder' and sauros/σαυρος meaning 'lizard', and from the Latin excelsus, "to exceed in number", referring to the greater number of sacral vertebrae than in any other genus of sauropod known at the time.

Original (outdated) Apatosaurus excelsus skeletal mount at the AMNH

The finds — the largest dinosaur ever discovered at the time and nearly complete, lacking only a head, feet, and portions of the tail — were then prepared for what was to be the first ever mounted display of a sauropod skeleton, at Yale's Peabody Museum of Natural History in 1905. The missing bones were created using known pieces from close relatives of Brontosaurus. Sauropod feet that were discovered at the same quarry were added, as well as a tail fashioned to appear as Marsh believed it should, as well as a composite model of what he felt the skull of this massive creature might look like. This was not a delicate Diplodocus-style skull (which would later turn out to be more accurate[12]), but was composed of "the biggest, thickest, strongest skull bones, lower jaws and tooth crowns from three different quarries",[13] primarily those of Camarasaurus, the only other sauropod for which good skull material was known at the time. This method of reconstructing incomplete skeletons based on the more complete remains of related dinosaurs continues in museum mounts and life restorations to this day.

Despite the much-publicized debut of the mounted skeleton, which cemented the name Brontosaurus in the public consciousness, Elmer Riggs had published a paper in the 1903 edition of Geological Series of the Field Columbian Museum which argued that Brontosaurus was not different enough from Apatosaurus to warrant its own genus, and created the combination Apatosaurus excelsus: "In view of these facts the two genera may be regarded as synonymous. As the term 'Apatosaurus' has priority, 'Brontosaurus' will be regarded as a synonym."

Despite this, at least one paleontologist—Robert Bakker—argued in the 1990s that A. ajax and A. excelsus are in fact sufficiently distinct that the latter continues to merit a separate genus.[14] This idea has not been accepted by many palaeontologists.[9][15]

Palaeobiology

Apatosaurus femur in Cosmocaixa, Barcelona

Early on, it was believed that Apatosaurus was too massive to support its own weight on dry land, so it was theorized that the sauropod must have lived partly submerged in water, perhaps in a swamp. Recent findings do not support this. In fact, like its relative Diplodocus, Apatosaurus was a grazing animal with a very long neck and a long tail that served as a counterweight. One study found that diplodocid necks were less flexible than previously believed, and that sauropods like Apatosaurus were adapted to low browsing or ground feeding.[16]

In 2008, footprints of juvenile Apatosaurus were reported from Quarry Five in Morrison, Colorado. Discovered in 2006 by Matthew Mossbrucker, these footprints show that juveniles could run on their hind legs in a manner similar to that of the modern basilisk lizard.[17]

Posture

In the early 20th century, diplodocids like Apatosaurus were often portrayed with their necks held high up in the air, allowing them to graze from tall trees. More recently, scientists have argued that the heart would have had trouble sustaining sufficient blood pressure to oxygenate the brain. Furthermore, more recent studies have shown that the structure of the neck vertebrae would not have permitted the neck to bend far upwards.[18][19] However, subsequent studies demonstrated that all tetrapods appear to hold their necks at the maximum possible vertical extension when in a normal, alert posture, and argued that the same would hold true for sauropods barring any unknown, unique characteristics that set the soft tissue anatomy of their necks apart from other animals. Apatosaurus like Diplodocus would have held its neck at about a 45 degree angle with the head pointed downwards in a resting posture.[20]

Physiology

With such a large body mass, combined with a long neck, physiologists encounter problems determining how these animals managed to breathe.

Beginning with the assumption that Apatosaurus, like crocodilians, did not have a diaphragm, the dead-space volume (the amount of unused air remaining in the mouth, trachea and air tubes after each breath) has been estimated at about 184 liters for a 30 ton specimen.

Its tidal volume (the amount of air moved in or out during a single breath) has been calculated based on the following respiratory systems:

  • 904 liters if avian
  • 225 liters if mammalian
  • 19 liters if reptilian.

On this basis, its respiratory system could not have been reptilian, as its tidal volume would not have been able to replace its dead-space volume. Likewise, the mammalian system would only provide a fraction of new air on each breath. Therefore, it must have had either a system unknown in the modern world or one like birds, i.e. multiple air sacs and a flow-through lung. Furthermore, an avian system would only need a lung volume of about 600 liters compared to a mammalian requirement of 2,950 liters, which would exceed the available space. The overall thoracic volume of Apatosaurus has been estimated at 1,700 liters allowing for a 500-liter, four-chambered heart (like birds, not three-chambered like reptiles) and a 900-liter lung capacity. That would allow about 300 liters for the necessary tissue. Assuming Apatosaurus had an avian respiratory system and a reptilian resting-metabolism, it would need to consume only about 262 liters (69 gallons) of water per day.[21]

Tail

An article that appeared in the November 1997 issue of Discover Magazine reported research into the mechanics of Apatosaurus tails by Nathan Myhrvold, a computer scientist from Microsoft. Myhrvold carried out a computer simulation of the tail, which in diplodocids like Apatosaurus was a very long, tapering structure resembling a bullwhip. This computer modeling suggested that sauropods were capable of producing a whip-like cracking sound of over 200 decibels, comparable to the volume of a cannon.[22]

In popular culture

Illustration from the early 20th century by Charles R. Knight

The length of time taken for Marsh's misclassification to be brought to public notice meant that the name Brontosaurus, associated as it was with one of the largest dinosaurs, became so famous that it persisted long after the name had officially been abandoned in scientific use. The terms brontosaurus, brontosaurs, and brontosaurians (no capital 'B'; no italics) are often used to refer generically to any of the sauropod dinosaurs.

As late as 1989, the U.S. Post Office issued four "dinosaur" stamps, Tyrannosaurus, Stegosaurus, "Pteradon" (misspelling of Pteranodon, which is a pterosaur and not a dinosaur) and Brontosaurus. The inclusion of these last two led to complaints of "fostering scientific illiteracy."[23] The Post Office defended itself (in Postal Bulletin 21744) by saying, "Although now recognized by the scientific community as Apatosaurus, the name 'Brontosaurus' was used for the stamp because it is more familiar to the general population."

Stephen Jay Gould supported this position in his essay "Bully for Brontosaurus", though he echoed Riggs' original argument that "Brontosaurus" is a synonym for "Apatosaurus". Nevertheless, he noted that the creature has developed and continues to maintain an independent existence in the popular imagination.[24]

Brontosaurus has often been depicted in cinema; the 1925 silent film The Lost World featured, using special effects by Willis O'Brien, a battle between a Brontosaurus and an Allosaurus. King Kong (1933) featured a Brontosaurus, as did the 2005 remake, described using the fictional scientific name "Brontosaurus baxteri", or Baxter's Thunder-Lizard, after a character in the film. The 1933 Brontosaurus was inaccurately portrayed as a carnivore. The brontosaur of the 2005 film is noticeably different from the modern view of Apatosaurus, with a square head, low-hanging tail, and snake-like neck reminiscent of 1930s period depictions of the species in art.

When George Lucas made his special edition of Star Wars Episode IV: A New Hope in 1997, he added some large, long-necked animals based on the Brachiosaurus digital model from Jurassic Park. At an early stage he altered the CG department's suggested name 'Bronto,' taken from 'Brontosaurus,' to 'Ronto'.[25]

In the TV sitcom Dinosaurs, Fran's friend Monica is an Apatosaurus[26] real estate agent (shown as a bright blue neck and head, wearing a pearl necklace) voiced by Suzie Plakson.

In the children's movie series, The Land Before Time, the main character, Littlefoot, is an Apatosaurus.

See also

References

  1. ^ Foster, J. (2007). "Appendix." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. pp. 327-329.
  2. ^ a b Holtz, Thomas R. Jr. (2008) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages Supplementary Information
  3. ^ Taylor, M.P. and Naish, D. (2005). "The phylogenetic taxonomy of Diplodocoidea (Dinosauria: Sauropoda)." PaleoBios, 25(2): 1–7. (download here)
  4. ^ Harris, J.D. (2006). "The significance of Suuwassea emiliae (Dinosauria: Sauropoda) for flagellicaudatan intrarelationships and evolution." Journal of Systematic Palaeontology, 4(2): 185–198.
  5. ^ a b Lovelace, David M. (2007). "Morphology of a specimen of Supersaurus (Dinosauria, Sauropoda) from the Morrison Formation of Wyoming, and a re-evaluation of diplodocid phylogeny". Arquivos do Museu Nacional 65 (4): 527–544. 
  6. ^ Carpenter, K. and McIntosh, J. (1994). "Upper Jurassic sauropod babies from the Morrison Formation", In: K. Carpenter, K. F. Hirsch, and J. R. Horner (eds.), Dinosaur Eggs and Babies. Cambridge University Press, Cambridge 265–278
  7. ^ Upchurch, Paul; Tomida, Yukimitsu; and Barrett, Paul M. (2004). "A new specimen of Apatosaurus ajax (Sauropoda: Diplodocidae) from the Morrison Formation (Upper Jurassic) of Wyoming, USA." National Science Museum monographs 26: i-118 ISSN:13429574
  8. ^ Bakker, R.T. (1998). "Dinosaur mid-life crisis: the Jurassic-Cretaceous transition in Wyoming and Colorado". In: S.G. Lucas, J.I. Kirkland, & J.W. Estep (eds.) Lower and Middle Cretaceous Terrestrial Ecosystems; New Mexico Museum of Natural History and Science Bulletin, 14: 67–77.
  9. ^ a b Upchurch, P., Barrett, P.M. and Dodson, P. (2004). "Sauropoda". In Weishampel, D.B., Osmólska, H., and Dodson, P. (eds.), The Dinosauria (2nd edition). University of California Press, Berkeley 259–322.
  10. ^ Hartman, Scott (2005 February 13). ""Eobrontosaurus" is not Camarasaurus". The Dinosaur Mailing List Archives. http://dml.cmnh.org/2005Feb/msg00289.html. Retrieved 27 January 2010. 
  11. ^ Carpenter, Kenneth; Tidwell, Virgina (1998). "Preliminary Description of a Brachiosaurus Skull from Felch Quarry 1, Garden Park, Colorado". in Carpenter, Kenneth; Chure, Dan; Kirkland, James Ian. The Upper Jurassic Morrison Formation: an interdisciplinary study. Taylor & Francis. ISBN 9056991833. http://books.google.com/books?id=CLEPeg_SjTcC&pg=PA69. 
  12. ^ 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.
  13. ^ Bakker, Robert (1994). "The Bite of the Bronto" Earth 3:(6):26–33.
  14. ^ Bakker, R.T. (1998). "Dinosaur mid-life crisis: the Jurassic-Cretaceous transition in Wyoming and Colorado". In: S.G. Lucas, J.I. Kirkland, & J.W. Estep (eds.) Lower and Middle Cretaceous Terrestrial Ecosystems; New Mexico Museum of Natural History and Science Bulletin, 14: 67–77.
  15. ^ McIntosh, J.S. (1995). "Remarks on the North American sauropod Apatosaurus Marsh". Sixth Symposium on Mesozoic Terrestrial Ecosystems and Biota, Short Papers, A. Sun and Y. Wang (eds.), China Ocean Press, Beijing 119–123
  16. ^ Stevens, Kent A.; Parrish, JM (1999). "Neck Posture and Feeding Habits of Two Jurassic Sauropod Dinosaurs". Science 284 (5415): 798–800. doi:10.1126/science.284.5415.798. PMID 10221910. http://www.sciencemag.org/cgi/content/abstract/284/5415/798. Retrieved 2008-08-03. 
  17. ^ Rajewski, Genevieve (May 2008). "Where Dinosaurs Roamed". Smithsonian: 20–24. http://www.smithsonianmag.com/history-archaeology/phenom-dino-200805.html. Retrieved 2008-04-30. 
  18. ^ Stevens KA, Parrish JM (2005). "Neck Posture, Dentition and Feeding Strategies in Jurassic Sauropod Dinosaurs". in Carpenter, Kenneth and Tidswell, Virginia (ed.). Thunder Lizards: The Sauropodomorph Dinosaurs. Indiana University Press. pp. 212–232. ISBN 0-253-34542-1. OCLC 57202057 61128849 218768170 57202057 61128849. 
  19. ^ Upchurch, P, et al. (2000). ""Neck Posture of Sauropod Dinosaurs"" (PDF). Science 287, 547b (2000); DOI: 10.1126/science.287.5453.547b. http://www.sciencemag.org/cgi/reprint/287/5453/547b.pdf. Retrieved 2008-08-05. 
  20. ^ Taylor, M.P., Wedel, M.J., and Naish, D. (2009). "Head and neck posture in sauropod dinosaurs inferred from extant animals". Acta Palaeontologica Polonica 54 (2), 2009: 213-220 abstract
  21. ^ Paladino, F.V., Spotila, J.R., and Dodson, P. (1997). "A Blueprint for Giants: Modeling the Physiology of Large Dinosaurs." In Farlow, J.O. and Brett-Surman, M.K. (eds.), The Complete Dinosaur, Indiana University Press, 491–504. doi0253333490.
  22. ^ Zimmer, C. (1997). "Dinosaurs in Motion." Discover, 1 Nov 1997. [1] Accessed 27 Jul 2008.
  23. ^ " Topics of The Times; Leapin' Lizards!" The New York Times, 1989-10-11. Last accessed 2008-06-08.
  24. ^ Gould, S.J. (1991). Bully for Brontosaurus: Reflections in Natural History, W. W. Norton & Co., 540pp.
  25. ^ "Ronto". Databank. Star Wars.com. http://www.starwars.com/databank/creature/ronto/index.html. Retrieved 2009-01-13. 
  26. ^ "I loved Monica (always thought she was a Brontosaurus...)" personal communication from Suzie Plakson dated Jan. 4, 2010

External links


Wikispecies

Up to date as of January 23, 2010

From Wikispecies

Taxonavigation

Main Page
Cladus: Eukaryota
Supergroup: Unikonta
Cladus: Opisthokonta
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclassis: Tetrapoda
Classis: Reptilia
Subclassis: Diapsida
Infraclassis: Archosauromorpha
Divisio: Archosauria
Subsectio: Ornithodira
Superordo: Dinosauria
Ordo: Saurischia
Taxon: Eusaurischia
Subordo: Sauropodomorpha
Infraordo: Sauropoda
Taxon: Eusauropoda
Taxon: Neosauropoda
Superfamilia: Diplodocoidea
Familia: Diplodocidae
Subfamilia: Apatosaurinae
Genus: Apatosaurus
Species: A. ajax - A. excelsus - A. louisae

Name

Apatosaurus Marsh, 1877

Synonymy

  • Brontosaurus Marsh, 1879

Vernacular Name


Simple English

Apatosaurus
Fossil range: Upper Jurassic
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Sauropsida
Superorder: Dinosauria
Order: Saurischia
Suborder: Sauropodomorpha
Infraorder: Sauropoda
Family: Diplodocidae
Genus: Apatosaurus
Marsh, 1877

Apatosaurus was a sauropod dinosaur which lived in the Jurassic period. It was known before as Brontosaurus.

It grew as big as 21 meters long, 4.5 meters tall at the hip, and weighed up to 23 metric tons. It ate plants. The bones of Apatosaurus have been found in Wyoming, Colorado, Oklahoma, and Utah in the United States.

When it was first found, scientists thought that Apatosaurus lived partly under water, since it could not hold its own weight on dry land. Now they think it lived on dry land, probably in herds.

The cervical vertebrae were less elongated and more solid than those of Diplodocus. The bones of the leg were much stockier (despite being longer), implying a more robust animal. The tail was held above the ground during normal locomotion. Like most sauropods, Apatosaurus had only a single large claw on each forelimb, with the first three toes on the hind limb possessing claws.

There are three species of Apatosaurus:

  • A. ajax was discovered by Othniel Charles Marsh in 1877.
  • A. excelsus (originally named Brontosaurus excelsus) was discovered by Marsh in 1879.
  • A. louisae was discovered by William Holland in 1915.
  • Another dinosaur species discovered in 1994 was at first named A. yahnahpin, but in 1998, it was renamed Eobrontosaurus yahnahpin.

The Brontosaurus story

Brontosaurus (meaning "thunder lizard") was a dinosaur which is now considered to be Apatosaurus. Othniel Charles Marsh described it as a new type of dinosaur.

The Brontosaurus became exceedingly popular, and the name "Brontosaurus" is often applied to the Apatosaurus. Some argued it should be called Apatosaurus as early as 1903. Most agreed with this by the 1970s, but some books still use the old name.

Look up Apatosaurus in Wikispecies, a directory of species
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