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{{short description|Sauropod dinosaur genus from Late Jurassic period}}
{{featured article}}
{{Use American English|date=
{{Use mdy dates|date=
{{Automatic taxobox
| fossil_range = [[Late Jurassic]] ([[Kimmeridgian]] to [[Tithonian]]), {{Geological range|152|
| image = Louisae.jpg
| image_caption = Mounted ''A. louisae'' (specimen CM 3018), [[Carnegie Museum of Natural History]]
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=== Initial discovery ===
[[File:Arthur Lakes illustration of Apatosaurus ajax and Atlantosaurus montanus at Morrison, Colorado.jpg|left|thumb|[[Arthur Lakes]]' painting of YPM crews excavating fossils of ''Apatosaurus ajax'' at Quarry 10 in Morrison.]]
The first ''Apatosaurus'' fossils were discovered by Arthur Lakes, a local miner, and his friend Henry C. Beckwith in the spring of 1877 in Morrison, a town in the eastern foothills of the [[Rocky Mountains]] in [[Jefferson County, Colorado]]. Arthur Lakes wrote to [[Othniel Charles Marsh]], Professor of [[Paleontology]] at [[Yale University]], and [[Edward Drinker Cope]], a paleontologist based in Philadelphia, about the discovery until eventually collecting several fossils and sending them to both paleontologists. Marsh named ''Atlantosaurus montanus'' based on some of the fossils sent and hired Lakes to collect the rest of the material at Morrison and send it to Yale, while Cope attempted to hire Lakes as well but was rejected.<ref name=":1">Kohl, M. F., & McIntosh, J. S. 1997, Discovering Dinosaurs in the Old West: The field journals of Arthur Lakes.</ref> One of the best specimens collected by Lakes in 1877 was a well preserved partial postcranial skeleton, including many vertebrae, and a partial braincase ([[Peabody Museum of Natural History|YPM]] VP 1860), which was sent to Marsh and named ''Apatosaurus ajax'' in November 1877.<ref name=":0" /><ref name=":1" /> The composite term ''Apatosaurus'' comes from the [[Ancient Greek|Greek]] words ''{{lang|grc-Latn|apatē}}'' ({{lang|grc|ἀπάτη}})/''{{lang|grc-Latn|apatēlos}}'' ({{lang|grc|ἀπατηλός}}) meaning "deception"/"deceptive", and ''{{lang|grc-Latn|sauros}}'' ({{lang|grc|[[wikt:σαῦρος|σαῦρος]]}}) meaning "lizard";<ref name="liddell" /> thus, "deceptive lizard". Marsh gave it this name based on the [[chevron (anatomy)|chevron]] bones, which are dissimilar to those of other dinosaurs; instead, the chevron bones of ''Apatosaurus'' showed similarities with those of [[mosasaur]]s,<ref name="marsh1877" /><ref name="Holtz2008" /> most likely that of the representative species ''[[Mosasaurus]]''. By the end of excavations at Lakes' quarry in Morrison, several partial specimens of ''Apatosaurus'' had been collected, but only the type specimen of ''A. ajax'' can be confidently referred to the species.<ref>{{Cite web |last=Marsh |first=O.T. |title=Apatosaurus ajax?; YPM VP 004833; North America; USA; Colorado; Jefferson County; Arthur Lakes |url=https://collections.peabody.yale.edu/search/Record/YPM-VP-004833 |access-date=March 11, 2022 |website=collections.peabody.yale.edu |language=en}}</ref><ref name=":0">{{Cite journal |last1=Tschopp |first1=Emanuel |last2=Mateus |first2=Octávio |last3=Benson |first3=Roger B. J. |date=April 7, 2015 |title=A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda)
During excavation and transportation, the bones of the holotype skeleton were mixed with those of another Apatosaurine individual originally described as ''Atlantosaurus immanis''; as a consequence, some elements cannot be ascribed to either specimen with confidence.<ref name="TMB2015" /> Marsh distinguished the new genus ''Apatosaurus'' from ''[[Atlantosaurus]]'' on the basis of the number of sacral vertebrae, with ''Apatosaurus'' possessing three and ''Atlantosaurus'' four. Recent research shows that traits usually used to distinguish taxa at this time were actually widespread across several taxa, causing many of the taxa named to be invalid, like ''Atlantosaurus''.<ref name=":0" /> Two years later, Marsh announced the discovery of a larger and more complete specimen (YPM VP 1980) from [[Como Bluff]], [[Wyoming]], he gave this specimen the name ''Brontosaurus excelsus''.<ref name="marsh1879" /> Also at Como Bluff, the Hubbell brothers working for Edward Drinker Cope collected a tibia, fibula, scapula, and several caudal vertebrae along with other fragments belonging to ''Apatosaurus'' in 1877–78 at Cope's Quarry 5 at the site.<ref>{{Cite web |date=2007 |title=Apatosaurus sp. AMNH FR 5755 |url=http://research.amnh.org/paleontology/search.php?action=detail&specimen_id=48563}}</ref> Later in 1884, Othniel Marsh named ''Diplodocus lacustris'' based on a chimeric partial dentary, snout, and several teeth collected by Lakes in 1877 at Morrison.<ref name=":0" /><ref name=":2">Mossbrucker, M. T., & Bakker, R. T. (October 2013). Missing muzzle found: new skull material referrable to Apatosaurus ajax (Marsh 1877) from the Morrison Formation of Morrison, Colorado. In ''Geological Society of America Abstracts with Programs'' (Vol. 45, p. 111).</ref> In 2013, it was suggested that the dentary of ''D. lacustris'' and its teeth were actually from ''Apatosaurus ajax'' based on its proximity to the type braincase of ''A. ajax''.<ref name=":2" /> All specimens currently considered ''Apatosaurus'' were from the [[Morrison Formation]], the location of the excavations of Marsh and Cope.<ref name="OM06" />[[File:Apatosaurus ajax sacrum.jpg|thumb|''A. ajax'' sacrum, illustrated in 1879]]
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While most other museums were using cast or sculpted ''Camarasaurus'' skulls on ''Apatosaurus'' mounts, the Yale Peabody Museum decided to sculpt a skull based on the lower jaw of a ''Camarasaurus'', with the cranium based on Marsh's 1891 illustration of the skull. The skull also included forward-pointing nasals{{snd}}something unusual for any dinosaur{{snd}}and fenestrae differing from both the drawing and other skulls.<ref name="camarasaurusbully" />
[[File:Apatosaurus louisae side (Morrison Formation, Upper Jurassic; Carnegie Quarry, Dinosaur National Monument, northeastern Utah, USA).jpg|thumb|left|Side view of ''A. louisae'' CM{{nbsp}}3018 mounted with a cast of skull CM{{nbsp}}11162]]
No ''Apatosaurus'' skull was mentioned in literature until the 1970s when [[John Stanton McIntosh]] and David Berman redescribed the skulls of ''Diplodocus'' and ''Apatosaurus''. They found that though he never published his opinion, Holland was almost certainly correct, that ''Apatosaurus'' had a ''Diplodocus''-like skull. According to them, many skulls long thought to pertain to ''Diplodocus'' might instead be those of ''Apatosaurus''. They reassigned multiple skulls to ''Apatosaurus'' based on associated and closely associated vertebrae. Even though they supported Holland, it was noted that ''Apatosaurus'' might have possessed a ''Camarasaurus''-like skull, based on a disarticulated ''Camarasaurus''-like tooth found at the precise site where an ''Apatosaurus'' specimen was found years before.<ref name="mcintosh&berman1975" /> On October{{nbsp}}20, 1979, after the publications by McIntosh and Berman, the first true skull of ''Apatosaurus'' was mounted on a skeleton in a museum, that of the Carnegie.<ref name="parsons" /> In 1998, it was suggested that the Felch Quarry skull that Marsh had included in his 1896 skeletal restoration instead belonged to ''[[Brachiosaurus]]''.<ref name="carpenter98" /> This was supported in 2020 with a redescription of the [[Brachiosauridae|brachiosaurid]] material found at the Felch Quarry.<ref name="D'Emic-2019">{{Cite journal |last1=D'Emic |first1=Michael D. |last2=Carrano |first2=Matthew T. |date=June 28, 2019 |title=Redescription of Brachiosaurid Sauropod Dinosaur Material From the Upper Jurassic Morrison Formation, Colorado, USA |journal=The Anatomical Record |volume=303 |issue=4 |pages=732–758 |doi=10.1002/ar.24198 |pmid=31254331 |s2cid=195765189 |issn=1932-8486|doi-access=free}}</ref>
=== Recent discoveries and
In 2011, the first specimen of ''Apatosaurus'' where a skull was found articulated with its cervical vertebrae was described. This specimen, [[Cincinnati Museum Center|CMC]]{{nbsp}}VP{{nbsp}}7180, was found to differ in both skull and neck features from ''A.{{nbsp}}louisae'', but shared many features of the cervical vertebrae with ''A.{{nbsp}}ajax''.<ref name="barrettetal11" /> Another well-preserved skull is [[Brigham Young University]] specimen 17096, a well-preserved skull and skeleton, with a preserved braincase. The specimen was found in Cactus Park Quarry in western [[Colorado]].<ref name="balanoff2010" /> In 2013, Matthew Mossbrucker and several other authors published an abstract that described a premaxilla and maxilla from Lakes' original quarry in Morrison and referred the material to ''Apatosaurus ajax.''<ref name=":2" />
[[File:Brontosaurus infographic.svg|thumb|left|261x261px|Infographic explaining the history of ''Brontosaurus'' and ''Apatosaurus'' according to Tschopp ''et{{nbsp}}al.'' 2015]]
Almost all modern paleontologists agreed with Riggs that the two dinosaurs should be classified together in a single genus. According to the rules of the [[International Code of Zoological Nomenclature|ICZN]] (which governs the scientific names of animals), the name ''Apatosaurus'', having been published first, has priority as the official name; ''Brontosaurus'' was considered a [[synonym (taxonomy)|junior synonym]] and was therefore long discarded from formal use.<ref name="taylor10"/><ref name="endeavour"/><ref name="Dinosauria04"/><ref name="Macintosh"/> Despite this, at least one paleontologist{{snd}}[[Robert T. Bakker]]{{snd}}argued in the 1990s that ''A.{{nbsp}}ajax'' and ''A.{{nbsp}}excelsus'' were in fact sufficiently distinct for the latter to merit a separate genus.<ref name="Bakker98"/>
In 2015, Emanuel Tschopp, [[Octávio Mateus]], and Roger Benson released a paper on diplodocoid systematics, and proposed that genera could be diagnosed by thirteen differing characters, and species separated based on six. The minimum number for generic separation was chosen based on the fact that ''A.{{nbsp}}ajax'' and ''A.{{nbsp}}louisae'' differ in twelve characters, and ''Diplodocus carnegiei'' and ''D.{{nbsp}}hallorum'' differ in eleven characters. Thus, thirteen characters were chosen to validate the separation of genera. The six differing features for specific separation were chosen by counting the number of differing features in separate specimens generally agreed to represent one species, with only one differing character in ''D.{{nbsp}}carnegiei'' and ''A.{{nbsp}}louisae'', but five differing features in ''B.{{nbsp}}excelsus''. Therefore, Tschopp et{{nbsp}}al. argued that ''Apatosaurus excelsus'', originally classified as ''Brontosaurus excelsus'', had enough morphological differences from other species of ''Apatosaurus'' that it warranted being reclassified as a separate genus again. The conclusion was based on a comparison of 477 morphological characteristics across 81 different dinosaur individuals. Among the many notable differences are the wider{{snd}}and presumably stronger{{snd}}neck of ''Apatosaurus'' species compared to ''B.{{nbsp}}excelsus''. Other species previously assigned to ''Apatosaurus'', such as ''Elosaurus parvus'' and ''Eobrontosaurus yahnahpin'' were also reclassified as ''Brontosaurus''. Some features proposed to separate ''Brontosaurus'' from ''Apatosaurus'' include: posterior dorsal vertebrae with the centrum longer than wide; the scapula rear to the [[acromion|acromial edge]] and the distal blade being excavated; the acromial edge of the distal scapular blade bearing a rounded expansion; and the ratio of the proximodistal length to transverse breadth of the [[Talus bone|astragalus]] 0.55 or greater.<ref name=TMB2015/> Sauropod expert [[Michael D'Emic]] pointed out that the criteria chosen were to an extent arbitrary and that they would require abandoning the name ''Brontosaurus'' again if newer
===Valid species===
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[[File:Apatosaurus caudal vertebrae.png|thumb|Tail vertebrae of specimen FMNH P25112, showing pneumatic fossae (holes)]]
Given the large body mass and long neck of sauropods like ''Apatosaurus'', physiologists have encountered problems determining how these animals breathed. Beginning with the assumption that, like [[crocodilia]]ns, ''Apatosaurus'' did not have a [[thoracic diaphragm|diaphragm]], the [[dead space (physiology)|dead-space volume]] (the amount of unused air remaining in the mouth, trachea, and air tubes after each breath) has been estimated at
On this basis, its respiratory system would likely have been [[parabronchi]], with multiple pulmonary air sacs as in [[avian lungs]], and a flow-through lung. An avian respiratory system would need a lung volume of about {{convert|600|L|m3|order=flip|abbr=on}} compared with a mammalian requirement of {{convert|2,950|L|m3|order=flip|abbr=on}}, which would exceed the space available. The overall thoracic volume of ''Apatosaurus'' has been estimated at {{convert|1,700|L|m3|order=flip|abbr=on}}, allowing for a {{convert|500|L|m3|order=flip|abbr=on}}, four-chambered heart and a {{convert|900|L|m3|order=flip|abbr=on}} lung capacity. That would allow about {{convert|300|L|m3|order=flip|abbr=on}} for the necessary tissue.<ref name="paladinoetal1997"/> Evidence for the avian system in ''Apatosaurus'' and other sauropods is also present in the [[Skeletal pneumaticity|pneumaticity]] of the vertebrae. Though this plays a role in reducing the weight of the animal, Wedel (2003) states they are also likely connected to air sacs, as in birds.<ref name="Wedel 2003"/>
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James Spotila ''et al.'' (1991) concludes that the large body size of sauropods would have made them unable to maintain high metabolic rates because they would not have been able to release enough heat.<ref name="spotila91"/> They assumed sauropods had a reptilian respiratory system. Wedel says that an avian system would have allowed it to dump more heat.<ref name="Wedel 2003"/> Some scientists state that the heart would have had trouble sustaining sufficient blood pressure to oxygenate the brain.<ref name="Pierson"/> Others suggest that the near-horizontal posture of the head and neck would have eliminated the problem of supplying blood to the brain because it would not have been elevated.<ref name="StevensParrish99"/>
James Farlow (1987) calculates that an ''Apatosaurus''-sized dinosaur about {{convert|35|t|LT ST|abbr=on}} would have possessed {{convert|5.7|t|LT ST|abbr=on}} of fermentation contents, though he cautions that the regression equation being used is based on living mammals which are much smaller and physiologically different.<ref name="farlow87"/> Assuming ''Apatosaurus'' had an avian respiratory system and a reptilian resting-metabolism, Frank Paladino et{{nbsp}}al. (1997) estimate the animal would have needed to consume only about {{convert|262|L
===Growth===
[[File:Baby Apatosaurus OMNH.jpg|thumb|left|Juvenile ''A.'' sp. mount, Sam Noble Oklahoma Museum of Natural History]]
A 1999 microscopic study of ''Apatosaurus'' and ''Brontosaurus'' bones concluded the animals grew rapidly when young and reached near-adult sizes in about 10{{nbsp}}years.<ref name=Curry99/> In 2008, a study on the growth rates of sauropods was published by Thomas Lehman and Holly Woodward. They said that by using growth lines and length-to-mass ratios, ''Apatosaurus'' would have grown to 25{{nbsp}}t (25 long tons; 28 short tons) in 15{{nbsp}}years, with growth peaking at {{convert|5000|kg|abbr=on|-2}} in a single year. An alternative method, using limb length and body mass, found ''Apatosaurus'' grew {{convert|520|kg|lb|abbr=on}} per year, and reached its full mass before it was about 70{{nbsp}}years old.<ref name="lehman&woodward"/> These estimates have been called unreliable because the calculation methods are not sound; old growth lines would have been obliterated by bone
Long-bone histology enables researchers to estimate the age that a specific individual reached. A study by Eva Griebeler et{{nbsp}}al. (2013) examined long-bone histological data and concluded the ''Apatosaurus'' sp.{{nbsp}}SMA{{nbsp}}0014 weighed {{convert|20206|kg|ST|1|abbr=on}}, reached sexual maturity at 21{{nbsp}}years, and died aged 28. The same growth model indicated ''Apatosaurus'' sp.{{nbsp}}BYU 601–17328 weighed {{convert|18178|kg|ST|1|abbr=on}}, reached sexual maturity at 19{{nbsp}}years, and died aged 31.<ref name="griebeler"/>
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An article published in 1997 reported research of the mechanics of ''Apatosaurus'' tails by [[Nathan Myhrvold]] and paleontologist [[Philip J. Currie]]. 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 diplodocids were capable of producing a whiplike cracking sound of over 200 [[decibel]]s, comparable to the volume of a cannon being fired.<ref name="myhrvold"/>
A pathology has been identified on the tail of ''Apatosaurus'', caused by a growth defect. Two caudal vertebrae are seamlessly fused along the entire articulating surface of the bone, including the arches of the neural spines. This defect might have been caused by the lack or inhibition of the substance that forms intervertebral disks or joints.<ref name="lovelace14"/> It has been proposed that the whips could have been used in combat and defense, but the tails of diplodocids were quite light and narrow compared to ''[[Shunosaurus]]'' and [[mamenchisaurid]]s, and thus to injure another animal with the tail would severely injure the tail itself.<ref name="myhrvold">{{cite journal|last1=Myhrvold|first1=N.P.|last2=Currie|first2=P.J.|title=Supersonic sauropods? Tail dynamics in the diplodocids|journal=Paleobiology|date=1997|volume=23|issue=4|pages=393–409|jstor=2401127|doi=10.1017/S0094837300019801|bibcode=1997Pbio...23..393M |s2cid=83696153 |url=http://doc.rero.ch/record/15579/files/PAL_E1438.pdf }}</ref> More recently, Baron (2020) considers the use of the tail as a bullwhip unlikely because of the potentially catastrophic muscle and skeletal damage such speeds could cause on the large and heavy tail. Instead, he proposes that the tails might have been used as a tactile organ to keep in touch with the individuals behind and on the sides in a group while migrating, which could have augmented cohesion and allowed communication among individuals while limiting more energetically demanding activities like stopping to search for dispersed individuals, turning to visually check on individuals behind, or communicating vocally.<ref>{{Cite journal |last=Baron |first=Matthew G. |date=October 3, 2021 |title=Tactile tails: a new hypothesis for the function of the elongate tails of diplodocid sauropods |url=https://doi.org/10.1080/08912963.2020.1769092 |journal=Historical Biology |volume=33 |issue=10 |pages=2057–2066 |doi=10.1080/08912963.2020.1769092 |bibcode=2021HBio...33.2057B |s2cid=219762797 |issn=0891-2963}}</ref>
==Paleoecology==
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''Apatosaurus'' was the second most common sauropod in the Morrison Formation ecosystem, after ''Camarasaurus''.<ref name="foster-2007"/><ref>{{Cite journal|last1=Foster|first1=John R.|last2=Peterson|first2=Joseph E.|date=September 1, 2016|title=First report of Apatosaurus (Diplodocidae: Apatosaurinae) from the Cleveland-Lloyd Quarry in the Upper Jurassic Morrison Formation of Utah: Abundance, distribution, paleoecology, and taphonomy of an endemic North American sauropod clade|url=https://www.sciencedirect.com/science/article/pii/S1871174X15000906|journal=Palaeoworld|language=en|volume=25|issue=3|pages=431–443|doi=10.1016/j.palwor.2015.11.006|issn=1871-174X}}</ref> ''Apatosaurus'' may have been more solitary than other Morrison Formation dinosaurs.<ref name=DBBM80/> Fossils of the genus have only been found in the upper levels of the formation. Those of ''Apatosaurus ajax'' are known exclusively from the upper [[Brushy Basin Member]], about 152–151 mya. ''A.{{nbsp}}louisae'' fossils are rare, known only from one site in the upper Brushy Basin Member; they date to the late Kimmeridgian stage, about 151{{nbsp}}mya. Additional ''Apatosaurus'' remains are known from similarly aged or slightly younger rocks, but they have not been identified as any particular species,<ref name=turner1999/> and thus may instead belong to ''Brontosaurus''.<ref name=TMB2015/>
The Morrison Formation records a time when the local environment was dominated by gigantic sauropod dinosaurs.<ref name="foster-2007"/> Dinosaurs known from the Morrison Formation include the theropods ''[[Allosaurus]]'', ''[[Ceratosaurus]]'', ''[[Ornitholestes]]'', ''[[Saurophaganax]]'', and ''[[Torvosaurus]]''; the sauropods ''[[Brontosaurus]]'', ''[[Brachiosaurus]]'', ''Camarasaurus'', and ''[[Diplodocus]]''; and the [[ornithischia]]ns ''[[Camptosaurus]]'', ''[[Dryosaurus]]'', and ''[[Stegosaurus]]''.<ref name=DJCetal06/> ''Apatosaurus'' is commonly found at the same sites as ''Allosaurus'', ''Camarasaurus'', ''Diplodocus'', and ''Stegosaurus''.<ref name=DBBM80/> ''Allosaurus'' accounted for 70–75% of theropod specimens and was at the top [[trophic level]] of the Morrison food web.<ref name=JRF03a/> Many of the dinosaurs of the Morrison Formation are of the same genera as those seen in Portuguese rocks of the [[Lourinhã Formation]]{{snd}}mainly ''Allosaurus'', ''Ceratosaurus'', and ''Torvosaurus''{{snd}}or have a close counterpart{{snd}}''Brachiosaurus'' and ''[[Lusotitan]]'', ''Camptosaurus'' and ''[[Draconyx]]'', and ''Apatosaurus'' and ''[[Dinheirosaurus]]''.<ref name=OM06/> Other vertebrates that are known to have shared this paleo-environment include [[actinopterygii|ray-finned fishes]], frogs, [[salamander]]s, turtles, [[sphenodontia|sphenodonts]], lizards, terrestrial and aquatic [[crocodylomorpha|crocodylomorphs]], and several species of [[pterosaur]]. Shells of [[bivalve]]s and aquatic snails are also common. The flora of the period has been evidenced in fossils of green algae, fungi, mosses, [[equisetum|horsetails]], [[cycad]]s, [[ginkgo]]es, and several families of conifers. Vegetation varied from river-lining forests of [[tree fern]]s with fern [[understory]] ([[gallery forest]]s), to fern [[savanna]]s with occasional trees such as the ''[[Araucaria]]''-like conifer ''[[Brachyphyllum]]''.<ref name=KC06/>
==References==
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<ref name="Upchurch05">{{cite journal |url=http://ci.nii.ac.jp/naid/110004665753/ |title=A new specimen of ''Apatosaurus ajax'' (Sauropoda: Diplodocidae) from the Morrison Formation (Upper Jurassic) of Wyoming, USA |last1=Upchurch |first1=P. |last2=Tomida |first2=Y. |last3=Barrett |first3=P.M. |journal=National Science Museum Monographs |year=2005 |volume=26 |issue=118 |pages=1–156 |issn=1342-9574}}</ref>
<ref name="mazzettaetal2004">{{cite journal |last1=Mazzetta |first1=G.V. |last2=Christiansen |first2=P. |last3=Farina |first3=R.A. |url=http://www.miketaylor.org.uk/tmp/papers/Mazzetta-et-al_04_SA-dino-body-size.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.miketaylor.org.uk/tmp/papers/Mazzetta-et-al_04_SA-dino-body-size.pdf |archive-date=October 9, 2022 |url-status=live |title=Giants and bizarres: body size of some southern South American Cretaceous dinosaurs |journal=Historical Biology |year=2004 |volume=16 |issue=2–4 |pages=71–83 |issn=1029-2381 |doi=10.1080/08912960410001715132|bibcode=2004HBio...16...71M |citeseerx=10.1.1.694.1650 |s2cid=56028251 }}</ref>
<ref name="henderson">{{cite journal |title=Burly Gaits: Centers of mass, stability, and the trackways of sauropod dinosaurs |last=Henderson |first=D.M. |journal=Journal of Vertebrate Paleontology |jstor=4524642 |year=2006 |volume=26 |issue=4 |pages=907–921 |doi=10.1671/0272-4634(2006)26[907:BGCOMS]2.0.CO;2|s2cid=86216852 |url=http://doc.rero.ch/record/15149/files/PAL_E2423.pdf }}</ref>
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<ref name="sellers12">{{cite journal |title=March of the Titans: The Locomotor Capabilities of Sauropod Dinosaurs |last1=Sellers |first1=W.I. |last2=Margetts |first2=L. |last3=Coria |first3=R.A. |last4=Manning |first4=P.L. |journal=PLOS ONE |year=2012 |volume=8 |issue=10 |pages=e78733 |doi=10.1371/journal.pone.0078733 |pmid=24348896 |pmc=3864407|bibcode=2013PLoSO...878733S |doi-access=free }}</ref>
<ref name="TMB2015">{{cite journal |last1=Tschopp |first1=E. |last2=Mateus |first2=O. V. |last3=Benson |first3=R. B. J. |title=A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda) |journal=PeerJ |year=2015 |volume=3 |pages=e857 |doi=10.7717/peerj.857 |pmid=25870766 |pmc=4393826 |doi-access=free }}</ref>
<ref name="LHW07">{{cite journal |url=https://www.academia.edu/539710 |title=Morphology of a specimen of ''Supersaurus'' (Dinosauria, Sauropoda) from the Morrison Formation of Wyoming, and a re-evaluation of diplodocid phylogeny |last1=Lovelace |first1=D.M. |last2=Hartman |first2=S.A. |last3=Wahl |first3=W.R. |journal=Arquivos do Museu Nacional |year=2007 |volume=65 |issue=4 |pages=527–544 |issn=0365-4508|citeseerx=10.1.1.603.7472 }}</ref>
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<ref name="taylornaish05">{{cite journal |url=http://www.miketaylor.org.uk/dino/pubs/taylor-and-naish2005/TaylorNaish2005-diplodocoid-taxonomy.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.miketaylor.org.uk/dino/pubs/taylor-and-naish2005/TaylorNaish2005-diplodocoid-taxonomy.pdf |archive-date=October 9, 2022 |url-status=live |title=The phylogenetic taxonomy of Diplodocoidea (Dinosauria: Sauropoda) |last1=Taylor |first1=M.P. |author-link=Mike P. Taylor |last2=Naish |first2=D. |author-link2=Darren Naish |journal=PaleoBios |year=2005 |volume=25 |issue=2 |pages=1–7}}</ref>
<ref name="harris06">{{cite journal |url=http://cactus.dixie.edu/jharris/Flagellicaudatan_Phylogeny.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://cactus.dixie.edu/jharris/Flagellicaudatan_Phylogeny.pdf |archive-date=October 9, 2022 |url-status=live |title=The significance of ''Suuwassea emiliae'' (Dinosauria: Sauropoda) for flagellicaudatan intrarelationships and evolution |last=Harris |first=J.D. |journal=Journal of Systematic Palaeontology |year=2006 |volume=4 |issue=2 |pages=185–198 |doi=10.1017/S1477201906001805|bibcode=2006JSPal...4..185H |s2cid=9646734 }}</ref>
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<ref name="ghose">{{cite web |url=http://www.livescience.com/38895-sauropods-had-stiff-necks.html |title=Ouch! Long-Necked Dinosaurs Had Stiff Necks |publisher=livescience.com |date=August 15, 2013 |access-date=January 31, 2015 |last1=Ghose |first1=T.}}</ref>
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<ref name="farlow87">{{cite journal |title=Speculations About the Diet and Physiology of Herbivorous Dinosaurs |last=Farlow |first=J.A. |journal=Paleobiology |jstor=2400838 |year=1987 |volume=13 |issue=1 |pages=60–72|doi=10.1017/S0094837300008587 |s2cid=88396062 }}</ref>
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{{Portal bar|Dinosaurs|United States}}
[[Category:Apatosaurinae]]▼
[[Category:Dinosaurs of the Morrison Formation]]
[[Category:Fossil taxa described in 1877]]
[[Category:Paleontology in Colorado]]
[[Category:Paleontology in Wyoming]]
[[Category:Taxa named by Othniel Charles Marsh]]
[[Category:Multispecific sauropod genera]]
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