108-417: Diplodocoidea is a superfamily of sauropod dinosaurs , which included some of the longest animals of all time, including slender giants like Supersaurus , Diplodocus , Apatosaurus , and Amphicoelias . Most had very long necks and long, whip-like tails; however, one family (the dicraeosaurids ) are the only known sauropods to have re-evolved a short neck, presumably an adaptation for feeding low to
216-495: A basal titanosauriform. The tracks are wide-gauge, and the grouping as close to Sauropodichnus is also supported by the manus-to-pes distance, the morphology of the manus being kidney bean-shaped, and the morphology of the pes being subtriangular. It cannot be identified whether the footprints of the herd were caused by juveniles or adults, because of the lack of previous trackway individual age identification. Generally, sauropod trackways are divided into three categories based on
324-420: A bipedal posture at times, there would be evidence of stress fractures in the forelimb 'hands'. However, none were found after they examined a large number of sauropod skeletons. Heinrich Mallison (in 2009) was the first to study the physical potential for various sauropods to rear into a tripodal stance. Mallison found that some characters previously linked to rearing adaptations were actually unrelated (such as
432-526: A characteristic feature of all sauropods. These air spaces reduced the overall weight of the massive necks that the sauropods had, and the air-sac system in general, allowing for a single-direction airflow through stiff lungs, made it possible for the sauropods to get enough oxygen. This adaptation would have advantaged sauropods particularly in the relatively low oxygen conditions of the Jurassic and Early Cretaceous. The bird-like hollowing of sauropod bones
540-593: A corresponding seasonal drop in the quality of food during the dry season. The environment of Amphicoelias was essentially a savanna , similar to the arid environments in which modern giant herbivores are found, supporting the idea that poor-quality food in an arid environment promotes the evolution of giant herbivores. Carpenter argued that other benefits of large size, such as relative immunity from predators, lower energy expenditure, and longer life span, are probably secondary advantages. The Morrison Formation environment in which Amphicoelias lived would have resembled
648-455: A few tens of meters away from the giant vertebra. It is likely that this undescribed leg bone belonged to the same individual animal as the neural spine, but it was never collected or described. In 2018, A. fragillimus was given its own genus, Maraapunisaurus , and reclassified as a primitive rebbachisaurid. In 2010, an article was made available, but not formally published, by Henry Galiano and Raimund Albersdorfer in which they referred to
756-402: A great number of adaptations in their skeletal structure. Some sauropods had as many as 19 cervical vertebrae , whereas almost all mammals are limited to only seven. Additionally, each vertebra was extremely long and had a number of empty spaces in them which would have been filled only with air. An air-sac system connected to the spaces not only lightened the long necks, but effectively increased
864-422: A large energy saving for such a large animal. Reconstructions of the necks of Diplodocus and Apatosaurus have therefore often portrayed them in near-horizontal, so-called "neutral, undeflected posture". However, research on living animals demonstrates that almost all extant tetrapods hold the base of their necks sharply flexed when alert, showing that any inference from bones about habitual "neutral postures"
972-548: A large part of the sauropod diet. Carpenter also noted that the occasional presence of large petrified logs indicate the presence of 20–30 m (66–98 ft) tall trees, which would seem to conflict with the savanna comparison. However, the trees are rare, and since tall trees require more water than the savanna environment could generally provide, they probably existed in narrow tracts or "gallery forests" along rivers and gulleys where water could accumulate. Carpenter speculated that giant herbivores like Amphicoelias may have used
1080-484: A modern savanna, though since grasses did not appear until the Late Cretaceous , ferns were probably the dominant plant and main food source for Amphicoelias . Though Engelmann et al. (2004) dismissed ferns as a sauropod food source due to their relatively low caloric content, Carpenter argued that the sauropod digestive system, well adapted to handle low-quality food, allows for the consumption of ferns as
1188-513: A part in the different feeding and herding strategies. Since the segregation of juveniles and adults must have taken place soon after hatching, and combined with the fact that sauropod hatchlings were most likely precocial , Myers and Fiorillo concluded that species with age-segregated herds would not have exhibited much parental care. On the other hand, scientists who have studied age-mixed sauropod herds suggested that these species may have cared for their young for an extended period of time before
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#17327913636411296-490: A population of sauropods isolated on an island of the late Jurassic in what is now the Langenberg area of northern Germany . The diplodocoid sauropod Brachytrachelopan was the shortest member of its group because of its unusually short neck. Unlike other sauropods, whose necks could grow to up to four times the length of their backs, the neck of Brachytrachelopan was shorter than its backbone. Fossils from perhaps
1404-495: A position much above the shoulders for exploring the area or reaching higher. Another proposed function of the sauropods' long necks was essentially a radiator to deal with the extreme amount of heat produced from their large body mass. Considering that the metabolism would have been doing an immense amount of work, it would certainly have generated a large amount of heat as well, and elimination of this excess heat would have been essential for survival. It has also been proposed that
1512-483: A review of the evidence for various herd types, Myers and Fiorillo attempted to explain why sauropods appear to have often formed segregated herds. Studies of microscopic tooth wear show that juvenile sauropods had diets that differed from their adult counterparts, so herding together would not have been as productive as herding separately, where individual herd members could forage in a coordinated way. The vast size difference between juveniles and adults may also have played
1620-478: A second femur. The additional material, not mentioned by Cope, was found close in proximity to the holotype and was similar to Diplodocus , a relative of Amphicoelias . Their assignment was questioned by subsequent authors Emanuel Tschopp et al. in an analysis of Diplodocidae . During the description of Amphicoelias altus in 1877, Cope additionally named A. latus , for a femur and tail vertebrae. Following its description, Osborn and Mook in 1921 reidentified
1728-402: A separate species or even a separate genus for A. fragillimus . However, he went on to caution that the validity of A. fragillimus as a separate species is nearly impossible to determine without the original specimen to study. Although Amphicoelias latus is clearly not Amphicoelias , it is probably synonymous with Camarasaurus grandis rather than C. supremus because it was found lower in
1836-852: A slightly more parsimonious apatosaurine phylogeny, but a slightly more diplodocine morphology. The following cladogram of the Diplodocidae follows the species-level agreement tree of Tschopp et al. (2015) showing A. altus as the basalmost diplodocid. Amphicoelias altus Unnamed species Apatosaurus ajax Apatosaurus louisae Brontosaurus excelsus Brontosaurus yahnahpin Brontosaurus parvus Unnamed species Tornieria africana Dinheirosaurus lourinhanensis Supersaurus vivianae Leinkupal laticauda Galeamopus hayi Diplodocus carnegii Diplodocus hallorum Kaatedocus siberi Barosaurus lentus In his 2006 re-evaluation, Carpenter examined
1944-1478: A specimen-level phylogenetic analysis, as well as a species-level analysis. Their cladistic analysis is shown below. Haplocanthosaurus priscus [REDACTED] Zapalasaurus bonapartei Cathartesaura anaerobica Limaysaurus tessonei Nigersaurus taqueti [REDACTED] Demandasaurus darwini Dyslocosaurus polyonychius Suuwassea emilieae Dystrophaeus viaemalae Brachytrachelopan mesai [REDACTED] Tharosaurus indicus [REDACTED] Amargasaurus cazaui [REDACTED] Dicraeosaurus hansemanni [REDACTED] Amphicoelias altus ?Apatosaurinae gen. et sp. nov. Apatosaurus ajax [REDACTED] Apatosaurus louisae [REDACTED] Brontosaurus excelsus [REDACTED] Brontosaurus yahnahpin Brontosaurus parvus [REDACTED] ?Diplodocinae gen. et sp. nov. Tornieria africana Supersaurus lourinhanensis Supersaurus vivianae [REDACTED] Leinkupal laticauda Galeamopus hayi Diplodocus carnegiei [REDACTED] Diplodocus hallorum Kaatedocus siberi Barosaurus lentus [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] Sauropod Sauropoda ( / s ɔː ˈ r ɒ p ə d ə / ), whose members are known as sauropods ( / ˈ s ɔːr ə p ɒ d z / ; from sauro- + -pod , ' lizard -footed'),
2052-404: A stance to be unstable. Diplodocids, on the other hand, appear to have been well adapted for rearing up into a tripodal stance. Diplodocids had a center of mass directly over the hips, giving them greater balance on two legs. Diplodocids also had the most mobile necks of sauropods, a well-muscled pelvic girdle, and tail vertebrae with a specialised shape that would allow the tail to bear weight at
2160-455: A stilt-walker principle (suggested by amateur scientist Jim Schmidt) in which the long legs of adult sauropods allowed them to easily cover great distances without changing their overall mechanics. Along with other saurischian dinosaurs (such as theropods , including birds), sauropods had a system of air sacs , evidenced by indentations and hollow cavities in most of their vertebrae that had been invaded by them. Pneumatic, hollow bones are
2268-414: A wide gauge and lack of any claws or digits on the forefeet. Occasionally, only trackways from the forefeet are found. Falkingham et al. used computer modelling to show that this could be due to the properties of the substrate. These need to be just right to preserve tracks. Differences in hind limb and fore limb surface area, and therefore contact pressure with the substrate, may sometimes lead to only
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#17327913636412376-469: Is 1.4 m (4.6 ft) long, but the very proximal end is not fully preserved. Due to the robusticity of the femur Osborn & Mook in 1921 referred Amphicoelias latus to Camarasaurus supremus , making C. supremus the valid name for the material once called A. latus . The third named Amphicoelias species, A. fragillimus , was known only from a single, incomplete 1.5 m (4.9 ft) tall neural arch , either last or second to last in
2484-551: Is a clade of saurischian ('lizard-hipped') dinosaurs . Sauropods had very long necks, long tails, small heads (relative to the rest of their body), and four thick, pillar-like legs. They are notable for the enormous sizes attained by some species, and the group includes the largest animals to have ever lived on land. Well-known genera include Apatosaurus , Argentinosaurus , Alamosaurus , Brachiosaurus , Camarasaurus , Diplodocus , and Mamenchisaurus . The oldest known unequivocal sauropod dinosaurs are known from
2592-429: Is a notable size increase among sauropodomorphs, although scanty remains of this period make interpretation conjectural. There is one definite example of a small derived sauropodomorph: Anchisaurus , under 50 kg (110 lb), even though it is closer to the sauropods than Plateosaurus and Riojasaurus , which were upwards of 1 t (0.98 long tons; 1.1 short tons) in weight. Evolving from sauropodomorphs,
2700-472: Is also thicker than in Diplocodus . The foramen in the coracoid is large and centered on the short axis of the bone. The ulna is more elongate than any comparable bone known from Diplocodus . It has prominent articular faces for the humerus and radius, and narrows toward the incomplete distal end. The pubis of Amphicoelias is very fragmentary, and the only discernible characteristics are that it
2808-453: Is deeply unreliable. Meanwhile, computer modeling of ostrich necks has raised doubts over the flexibility needed for stationary grazing. Sauropod trackways and other fossil footprints (known as "ichnites") are known from abundant evidence present on most continents. Ichnites have helped support other biological hypotheses about sauropods, including general fore and hind foot anatomy (see Limbs and feet above). Generally, prints from
2916-399: Is discernible from the known remains. The centrum is very compressed in the middle in all dimensions, with a large lateral pleurocoel set inside a large lateral fossa . In Amphicoelias the neural arch is very tall, and along its side there is a prominent lamina extending from the posterior centrum to the prezygapophyses (articular surfaces with the neural arch of
3024-898: Is evidence that they preferred wet and coastal habitats. Sauropod footprints are commonly found following coastlines or crossing floodplains, and sauropod fossils are often found in wet environments or intermingled with fossils of marine organisms. A good example of this would be the massive Jurassic sauropod trackways found in lagoon deposits on Scotland 's Isle of Skye . Studies published in 2021 suggest sauropods could not inhabit polar regions. This study suggests they were largely confined to tropical areas and had metabolisms that were very different to those of other dinosaurs, perhaps intermediate between mammals and reptiles. New studies published by Taia Wyenberg-henzler in 2022 suggest that sauropods in North America declined due to undetermined reasons in regards to their niches and distribution during
3132-407: Is just a very large individual of A. altus , a position that most subsequent studies, including McIntosh 1998, Foster (2007), and Woodruff and Foster (2015) have agreed with. Carpenter (2006) disagreed about the synonymy of A. altus and A. fragillimus , however, citing numerous differences in the construction of the vertebra also noted by Cope, and suggested these differences are enough to warrant
3240-438: Is kept in digestion for significantly longer periods of time, allowing large animals to survive on lower-quality food sources. This is especially true of animals with a large number of 'fermentation chambers' along the intestine, which allow microbes to accumulate and ferment plant material, aiding digestion. Throughout their evolutionary history, sauropod dinosaurs were found primarily in semi-arid, seasonally dry environments, with
3348-420: Is long but thick, and has a small surface for articulation with the ilium . A single, slender right femur of Amphicoelias is known from the holotype, 1.524 m (5 ft) long. It is slightly longer than the femur of Camarasaurus supremus , but significantly less robust , being approximately round in cross-section and only 22 cm (8.7 in) wide. The shaft of the femur is gently curved towards
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3456-608: Is more robust overall. The distal end of the scapula, while only partially preserved, show that the expansion of the scapula blade was smaller than Camarasaurus but larger than Apatosaurus . 161 cm (63 in) long as preserved, the bone is noticeably thicker than in Diplodocus , but not quite as thick as in Camarasaurus . The coracoid found alongside the scapula is far more similar to Diplodocus than Camarasaurus , being round and longer than tall. However, it
3564-426: Is only one species of Amphicoelias and that it could be referred to Diplodocus as Diplodocus altus . They considered the name Amphicoelias to be a nomen oblitum . This conclusion was disputed by Emanuel Tschopp et al. in 2015, where Amphicoelias was analysed as part of an extensive specimen-level phylogenetic analysis of Diplodocidae. There were two strongly supported placements found for Amphicoelias , as
3672-632: Is shown in the fossil record. Moreover, it must be determined as to whether sauropod declines in North America was the result of a change in preferred flora that sauropods ate, climate, or other factors. It is also suggested in this same study that iguanodontians and hadrosauroids took advantage of recently vacated niches left by a decline in sauropod diversity during the late Jurassic and the Cretaceous in North America. Many lines of fossil evidence, from both bone beds and trackways, indicate that sauropods were gregarious animals that formed herds . However,
3780-477: Is uncertain in included material. When described by Edward Drinker Cope shortly after its discovery in 1877 , Amphicoelias was noted to include many back vertebrae , a single pubis , and a femur . However, after purchase and cataloging of the material by the AMNH, Henry Fairfield Osborn and Charles Mook described that the specimen had only two vertebrae, a pubis, femur, tooth , scapula , coracoid , ulna and
3888-421: Is unknown. The claw was largest (as well as tall and laterally flattened) in diplodocids, and very small in brachiosaurids, some of which seem to have lost the claw entirely based on trackway evidence. Titanosaurs may have lost the thumb claw completely (with the exception of early forms, such as Janenschia ). Titanosaurs were most unusual among sauropods, as, across their history as a clade, they lost not just
3996-399: The hyposphene , limiting the motion of vertebrae respective to one another. Amphicoeliidae and Amphicoelias were both found to be intermediate and poorly defined by paleontologist Othniel Charles Marsh in 1881 , wherein the primary feature-two mildly concave articular faces-was shown to be widespread and also found in sauropods like Brontosaurus excelsus . Amphicoelias latus
4104-489: The African elephant , can only reach lengths of 7.3 metres (24 ft). Others, like the brachiosaurids , were extremely tall, with high shoulders and extremely long necks. The tallest sauropod was the giant Barosaurus specimen at 22 m (72 ft) tall. By comparison, the giraffe , the tallest of all living land animals, is only 4.8 to 5.6 metres (15.74 to 18.3 ft) tall. The best evidence indicates that
4212-507: The Camarasaurus fossils also described by Cope. Cope listed multiple features to separate Amphicoelias and A. altus from their relatives. Unlike in Camarasaurus , the centra of dorsals did not have an opisthocoely , where the front end has a ball that fits into the socket of the preceding vertebra. Instead, Amphicoelias had amphicoelous vertebrae, where both ends are mildly to moderately concave. Because of this difference, Cope named two separate families to contain
4320-508: The Camarasaurus they were found alongside. Because of the uncertainty about the referral of these remains, in 2015 Emanuel Tschopp and colleagues hesitantly rejected the referral of the tooth, scapula and coracoid, but accepted the ulna referral. Based on collection data, the specimen was determined to have come from the Late Jurassic Morrison Formation , in the youngest layers, separate from those that held
4428-749: The Cretaceous Dakota Formation by paleontologist Edward Drinker Cope , from the same age as other Laelaps fossils. Among the assortment of fossils discovered, a specimen including multiple dorsal vertebrae , a pubis , and a femur was found by Aaron Ripley, Lucas' brother-in-law, in Quarry XII. They were sent to Cope on October 21, 1877. Cope concluded they belonged to a new taxon within Sauropoda , which Cope named Amphicoelias altus in December 1877. Cope determined that
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4536-742: The Early Jurassic . Isanosaurus and Antetonitrus were originally described as Triassic sauropods, but their age, and in the case of Antetonitrus also its sauropod status, were subsequently questioned. Sauropod-like sauropodomorph tracks from the Fleming Fjord Formation ( Greenland ) might, however, indicate the occurrence of the group in the Late Triassic . By the Late Jurassic (150 million years ago), sauropods had become widespread (especially
4644-527: The Tithonian ( Late Jurassic Period) of what is now Colorado , United States. Amphicoelias was moderately sized at about 18 metres (59 ft) in length and 15 metric tons (17 short tons) in body mass, shorter than its close relative Diplodocus . Its hindlimbs were very long and thin, and its forelimbs were proportionally longer than in relatives. The namesake fossil of the type species Amphicoelias altus , American Museum of Natural History 5764,
4752-473: The blue whale in size. The weight of Amphicoelias fragillimus was estimated at 122.4 metric tons with lengths of up to nearly 60 meters but 2015 research argued that these estimates were based on a diplodocid rather than the more modern rebbachisaurid, suggesting a much shorter length of 35–40 meters with mass between 80–120 tons. Additional finds indicate a number of species likely reached or exceeded weights of 40 tons. The largest land animal alive today,
4860-430: The bush elephant , weighs no more than 10.4 metric tons (11.5 short tons). Among the smallest sauropods were the primitive Ohmdenosaurus (4 m, or 13 ft long), the dwarf titanosaur Magyarosaurus (6 m or 20 ft long), and the dwarf brachiosaurid Europasaurus , which was 6.2 meters long as a fully-grown adult. Its small stature was probably the result of insular dwarfism occurring in
4968-491: The diplodocids and brachiosaurids ). By the Late Cretaceous , one group of sauropods, the titanosaurs , had replaced all others and had a near-global distribution. However, as with all other non-avian dinosaurs alive at the time, the titanosaurs died out in the Cretaceous–Paleogene extinction event . Fossilised remains of sauropods have been found on every continent, including Antarctica . The name Sauropoda
5076-497: The rorquals , such as the blue whale . But, unlike whales, sauropods were primarily terrestrial animals . Their body structure did not vary as much as other dinosaurs, perhaps due to size constraints, but they displayed ample variety. Some, like the diplodocids , possessed tremendously long tails, which they may have been able to crack like a whip as a signal or to deter or injure predators, or to make sonic booms . Supersaurus , at 33 to 34 metres (108 to 112 ft) long,
5184-458: The 1970s, the effects of sauropod air sacs on their supposed aquatic lifestyle began to be explored. Paleontologists such as Coombs and Bakker used this, as well as evidence from sedimentology and biomechanics , to show that sauropods were primarily terrestrial animals. In 2004, D.M. Henderson noted that, due to their extensive system of air sacs, sauropods would have been buoyant and would not have been able to submerge their torsos completely below
5292-432: The 19th and early 20th centuries concluded that sauropods were too large to have supported their weight on land, and therefore that they must have been mainly aquatic . Most life restorations of sauropods in art through the first three quarters of the 20th century depicted them fully or partially immersed in water. This early notion was cast in doubt beginning in the 1950s, when a study by Kermack (1951) demonstrated that, if
5400-466: The Middle Triassic of Argentina, weighed approximately 1 kg (2.2 lb) or less. These evolved into saurischia, which saw a rapid increase of bauplan size, although more primitive members like Eoraptor , Panphagia , Pantydraco , Saturnalia and Guaibasaurus still retained a moderate size, possibly under 10 kg (22 lb). Even with these small, primitive forms, there
5508-603: The Morrison Formation and the deeply concave articular faces on the caudal vertebrae are more consistent with C. grandis . Henry Fairfield Osborn and Charles Craig Mook noted the overall close similarity between Amphicoelias and Diplodocus , as well as a few key differences, such as proportionally longer forelimbs in Amphicoelias than in Diplodocus . The femur of Amphicoelias is unusually long, slender, and round in cross section; while this roundness
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#17327913636415616-550: The airflow through the trachea, helping the creatures to breathe in enough air. By evolving vertebrae consisting of 60% air, the sauropods were able to minimize the amount of dense, heavy bone without sacrificing the ability to take sufficiently large breaths to fuel the entire body with oxygen. According to Kent Stevens, computer-modeled reconstructions of the skeletons made from the vertebrae indicate that sauropod necks were capable of sweeping out large feeding areas without needing to move their bodies, but were unable to be retracted to
5724-418: The animal were submerged in several metres of water, the pressure would be enough to fatally collapse the lungs and airway. However, this and other early studies of sauropod ecology were flawed in that they ignored a substantial body of evidence that the bodies of sauropods were heavily permeated with air sacs . In 1878, paleontologist E.D. Cope had even referred to these structures as "floats". Beginning in
5832-560: The basalmost genus within Apatosaurinae , and as an apatosaurine nested between Brontosaurus excelsus and Brontosaurus yahnahpin . There were no unambiguous characters found to support an assignment within Apatosaurinae, so the authors instead opted to classify Amphicoelias as the basalmost diplodocid outside Apatosaurinae and Diplodocinae, having primitive features, minimal significant differences from either subfamily,
5940-539: The coarse scratches and gouges on the teeth of Dicraeosaurus suggest mid-height selective browsing in those taxa. This taxon is also noteworthy because diplodocoid sauropods had the highest tooth replacement rates of any vertebrates, as exemplified by Nigersaurus , which had new teeth erupting every 30 days. Most diplodocoids belong to Diplodocimorpha , a name first used by Calvo & Salgado (1995), who defined it as " Rebbachisaurus tessonei sp. nov., Diplodocidae, and all descendants of their common ancestor." The group
6048-535: The differences usually cited to differentiate Amphicoelias altus from the more well known Diplodocus are not significant and may be due to individual variation. Foster argued that Amphicoelias is probably the senior synonym of Diplodocus , and that if further research bears this out, the familiar name Diplodocus would need to be abandoned in favor of Amphicoelias , as was the case with Brontosaurus and its senior synonym Apatosaurus . In 2015, Woodruff and Foster reiterated this conclusion, stating that there
6156-410: The different morphs of vertebral centra, one being Camarasauridae and the other being Amphicoeliidae . As well, Camarasaurus possessed pleurocoels (openings in the side of the centrum) that were taller than long-contrasting to the condition in Amphicoelias - and a more robust pubis and femur. However, both families also had accessory articulations in the neural arch , which Cope termed
6264-523: The distance between opposite limbs: narrow gauge, medium gauge, and wide gauge. The gauge of the trackway can help determine how wide-set the limbs of various sauropods were and how this may have impacted the way they walked. A 2004 study by Day and colleagues found that a general pattern could be found among groups of advanced sauropods, with each sauropod family being characterised by certain trackway gauges. They found that most sauropods other than titanosaurs had narrow-gauge limbs, with strong impressions of
6372-405: The end of the Jurassic and into the latest Cretaceous. Why this is remains unclear, but some similarities in feeding niches between iguanodontians, hadrosauroids and sauropods have been suggested and may have resulted in some competition. However, this cannot fully explain the full decline in distribution of sauropods, as competitive exclusion would have resulted in a much more rapid decline than what
6480-423: The external claw but also completely lost the digits of the front foot. Advanced titanosaurs had no digits or digit bones, and walked only on horseshoe-shaped "stumps" made up of the columnar metacarpal bones. Print evidence from Portugal shows that, in at least some sauropods (probably brachiosaurids), the bottom and sides of the forefoot column was likely covered in small, spiny scales, which left score marks in
6588-488: The flesh miss these facts, inaccurately depicting sauropods with hooves capping the claw-less digits of the feet, or more than three claws or hooves on the hands. The proximal caudal vertebrae are extremely diagnostic for sauropods. The sauropods' most defining characteristic was their size. Even the dwarf sauropods (perhaps 5 to 6 metres, or 20 feet long) were counted among the largest animals in their ecosystem . Their only real competitors in terms of size are
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#17327913636416696-601: The forefeet are much smaller than the hind feet, and often crescent-shaped. Occasionally ichnites preserve traces of the claws, and help confirm which sauropod groups lost claws or even digits on their forefeet. Sauropod tracks from the Villar del Arzobispo Formation of early Berriasian age in Spain support the gregarious behaviour of the group. The tracks are possibly more similar to Sauropodichnus giganteus than any other ichnogenera, although they have been suggested to be from
6804-483: The forefeet trackways being preserved. In a study published in PLoS ONE on October 30, 2013, by Bill Sellers , Rodolfo Coria , Lee Margetts et al. , Argentinosaurus was digitally reconstructed to test its locomotion for the first time. Before the study, the most common way of estimating speed was through studying bone histology and ichnology . Commonly, studies about sauropod bone histology and speed focus on
6912-418: The forefoot bone ( metacarpal ) columns in eusauropods was semi-circular, so sauropod forefoot prints are horseshoe-shaped. Unlike elephants, print evidence shows that sauropods lacked any fleshy padding to back the front feet, making them concave. The only claw visible in most sauropods was the distinctive thumb claw (associated with digit I). Almost all sauropods had such a claw, though what purpose it served
7020-401: The gait and speed of Argentinosaurus , the study performed a musculoskeletal analysis. The only previous musculoskeletal analyses were conducted on hominoids , terror birds , and other dinosaurs . Before they could conduct the analysis, the team had to create a digital skeleton of the animal in question, show where there would be muscle layering, locate the muscles and joints, and finally find
7128-503: The ground. This adaptation was taken to the extreme in the highly specialized sauropod Brachytrachelopan . A study of snout shape and dental microwear in diplodocoids showed that the square snouts, large proportion of pits, and fine subparallel scratches in Apatosaurus , Diplodocus , Nigersaurus , and Rebbachisaurus suggest ground-height nonselective browsing; the narrow snouts of Dicraeosaurus , Suuwassea , and Tornieria and
7236-489: The growth of sauropods, their theropod predators grew also, as shown by an Allosaurus -sized coelophysoid from Germany . Amphicoelias altus Amphicoelias ( / ˌ æ m f ɪ ˈ s iː l i ə s / , meaning "biconcave", from the Greek ἀμφί, amphi : "on both sides", and κοῖλος, koilos : "hollow, concave") is a genus of herbivorous sauropod dinosaur that lived approximately 150 million years ago during
7344-447: The head in such a posture for long would have used some half of its energy intake. Further, to move blood to such a height—dismissing posited auxiliary hearts in the neck —would require a heart 15 times as large as of a similar-sized whale. The above have been used to argue that the long neck must instead have been held more or less horizontally, presumed to enable feeding on plants over a wide area with less need to move about, yielding
7452-445: The hip articulation, and straight close to the prominent articular condyles . A second, partial left femur was also found in the collections of the AMNH, and was assigned to the holotype specimen, while it was not mentioned by Cope. It lacks a majority of the upper bone, but the known shaft and end are very similar to the one figured by Cope, and it may be the left femur of the same individual. In 2007, John Foster suggested that
7560-490: The history of their study, scientists, such as Osborn , have speculated that sauropods could rear up on their hind legs, using the tail as the third 'leg' of a tripod. A skeletal mount depicting the diplodocid Barosaurus lentus rearing up on its hind legs at the American Museum of Natural History is one illustration of this hypothesis. In a 2005 paper, Rothschild and Molnar reasoned that if sauropods had adopted
7668-580: The incomplete nature, such lengths–the longest of any known dinosaur and sauropod–were largely ignored. In 2018 , Kenneth Carpenter renamed Amphicoelias fragillimus as the new genus Maraapunisaurus , and reclassified it from Diplodocidae to Rebbachisauridae . In 1877 , a number of fossils were discovered by Oramel William Lucas in rock outcrops in Colorado close to Cañon City . These bones, including some named Laelaps trihedrodon , Camarasaurus supremus and Caulodon , were assumed to be from
7776-418: The large thumb claw on the forefeet. Medium gauge trackways with claw impressions on the forefeet probably belong to brachiosaurids and other primitive titanosauriformes , which were evolving wider-set limbs but retained their claws. Primitive true titanosaurs also retained their forefoot claw but had evolved fully wide gauge limbs. Wide gauge limbs were retained by advanced titanosaurs, trackways from which show
7884-600: The largest dinosaur ever found were discovered in 2012 in the Neuquén Province of northwest Patagonia, Argentina. It is believed that they are from a titanosaur, which were amongst the largest sauropods. On or shortly before 29 March 2017 a sauropod footprint about 5.6 feet (1.7 meters) long was found at Walmadany in the Kimberley Region of Western Australia. The report said that it was the biggest known yet. In 2020 Molina-Perez and Larramendi estimated
7992-462: The long necks would have cooled the veins and arteries going to the brain, avoiding excessively heated blood from reaching the head. It was in fact found that the increase in metabolic rate resulting from the sauropods' necks was slightly more than compensated for by the extra surface area from which heat could dissipate. When sauropods were first discovered, their immense size led many scientists to compare them with modern-day whales . Most studies in
8100-597: The makeup of the herds varied between species. Some bone beds, for example a site from the Middle Jurassic of Argentina , appear to show herds made up of individuals of various age groups, mixing juveniles and adults. However, a number of other fossil sites and trackways indicate that many sauropod species travelled in herds segregated by age, with juveniles forming herds separate from adults. Such segregated herding strategies have been found in species such as Alamosaurus , Bellusaurus and some diplodocids . In
8208-466: The material as a specimen of Camarasaurus , an assignment followed by other authors who reviewed the material. A year later 1878 , Cope named the third species of Amphicoelias , A. fragillimus for a gigantic dorsal vertebra that was subsequently lost. Measuring approximately 2.7 m (8.9 ft) if reconstructed based on Diplodocus , early estimates for the length of the animal in life were between 40 and 60 m (130 and 200 ft) long. Due to
8316-519: The most massive were Argentinosaurus (65–80 metric tons ), Mamenchisaurus sinocanadorum (60-80 metric tons ), the giant Barosaurus specimen (60-80+ metric tons ) and Patagotitan with Puertasaurus (50-55 metric tons ). Meanwhile, 'mega-sauropods' such as Bruhathkayosaurus has long been scrutinized due to controversial debates on its validity, but recent photos re-surfacing in 2022 have legitimized it, allowing for more updated estimates that range between 110–170 tons, rivaling
8424-641: The muscle properties before finding the gait and speed. The results of the biomechanics study revealed that Argentinosaurus was mechanically competent at a top speed of 2 m/s (5 mph) given the great weight of the animal and the strain that its joints were capable of bearing. The results further revealed that much larger terrestrial vertebrates might be possible, but would require significant body remodeling and possible sufficient behavioral change to prevent joint collapse. Sauropods were gigantic descendants of surprisingly small ancestors. Basal dinosauriformes, such as Pseudolagosuchus and Marasuchus from
8532-431: The neck, and the head was evolved to be very small and light, losing the ability to orally process food. By reducing their heads to simple harvesting tools that got the plants into the body, the sauropods needed less power to lift their heads, and thus were able to develop necks with less dense muscle and connective tissue. This drastically reduced the overall mass of the neck, enabling further elongation. Sauropods also had
8640-505: The new species "A. brontodiplodocus" to Amphicoelias , based on several complete specimens found in the Dana Quarry of Big Horn Basin, Wyoming and held in a private collection. The specific name referred to their hypothesis based on these specimens that nearly all Morrison diplodocid species are either growth stages or represent sexual dimorphism among members of the genus Amphicoelias , but this analysis has been met with skepticism and
8748-669: The paleobiology of giant sauropods, including Amphicoelias , and addressed the question of why this group attained such a huge size. He pointed out that gigantic sizes were reached early in sauropod evolution, with very large sized species present as early as the late Triassic period, and concluded that whatever evolutionary pressure caused large size was present from the early origins of the group. Carpenter cited several studies of giant mammalian herbivores, such as elephants and rhinoceros , which showed that larger size in plant-eating animals leads to greater efficiency in digesting food. Since larger animals have longer digestive systems , food
8856-584: The point it touched the ground. Mallison concluded that diplodocids were better adapted to rearing than elephants , which do so occasionally in the wild. He also argues that stress fractures in the wild do not occur from everyday behaviour, such as feeding-related activities (contra Rothschild and Molnar). There is little agreement over how sauropods held their heads and necks, and the postures they could achieve in life. Whether sauropods' long necks could be used for browsing high trees has been questioned based on calculations suggesting that just pumping blood up to
8964-532: The postcranial skeleton, which holds many unique features, such as an enlarged process on the ulna , a wide lobe on the ilia , an inward-slanting top third of the femur , and an extremely ovoid femur shaft. Those features are useful when attempting to explain trackway patterns of graviportal animals. When studying ichnology to calculate sauropod speed, there are a few problems, such as only providing estimates for certain gaits because of preservation bias , and being subject to many more accuracy problems. To estimate
9072-575: The preceding vertebra). From directly behind the prezygapophyses, the diapophyes (lateral processes for rib articulation) project slightly upwards and outwards, surrounded by shallow fossae and a large lamina extending up the neural spine . The neural spine is thin, with a pair of ridges going up along either side on the edges. The distal end is wide compared to the main spine, but approximately subequal in length and width. A partial forelimb, provisionally referred to Amphicoelias by Osborn & Mook in 1921, resembles Diplodocus but
9180-642: The prints. In titanosaurs, the ends of the metacarpal bones that contacted the ground were unusually broad and squared-off, and some specimens preserve the remains of soft tissue covering this area, suggesting that the front feet were rimmed with some kind of padding in these species. Matthew Bonnan has shown that sauropod dinosaur long bones grew isometrically : that is, there was little to no change in shape as juvenile sauropods became gigantic adults. Bonnan suggested that this odd scaling pattern (most vertebrates show significant shape changes in long bones associated with increasing weight support) might be related to
9288-409: The publication itself has been disclaimed by its lead author, explaining that it is "obviously a drafted manuscript complete with typos, etc., and not a final paper. In fact, no printing or distribution has been attempted". Osborn and Mook, in 1921, provisionally synonymized A. fragillimus with A. altus , while sinking A. latus into Camarasaurus supremus , and suggesting also that A. fragillimus
9396-621: The sauropods were huge. Their giant size probably resulted from an increased growth rate made possible by tachymetabolic endothermy , a trait which evolved in sauropodomorphs. Once branched into sauropods, sauropodomorphs continued steadily to grow larger, with smaller sauropods, like the Early Jurassic Barapasaurus and Kotasaurus , evolving into even larger forms like the Middle Jurassic Mamenchisaurus and Patagosaurus . Responding to
9504-401: The scientists, the specializing of their diets helped the different herbivorous dinosaurs to coexist. Sauropod necks have been found at over 15 metres (49 ft) in length, a full six times longer than the world record giraffe neck. Enabling this were a number of essential physiological features. The dinosaurs' overall large body size and quadrupedal stance provided a stable base to support
9612-454: The series of back vertebrae. Based only on an illustration published in 1878, this vertebra would have measured 2.7 meters (8.9 ft) tall in life. However, it has been argued that the scale bar in the published description contained a typographical error, and the fossil vertebra was in fact only 1.38 meters (4.5 ft) tall. In addition to this vertebra, Cope's field notes contain an entry for an "[i]mmense distal end of femur”, located only
9720-451: The shorter hind legs free of the bottom, and using the front limbs to punt forward. However, due to their body proportions, floating sauropods would also have been very unstable and maladapted for extended periods in the water. This mode of aquatic locomotion , combined with its instability, led Henderson to refer to sauropods in water as "tipsy punters". While sauropods could therefore not have been aquatic as historically depicted, there
9828-409: The sides to create a wide foot as in elephants, the manus bones of sauropods were arranged in fully vertical columns, with extremely reduced finger bones (though it is not clear if the most primitive sauropods, such as Vulcanodon and Barapasaurus , had such forefeet). The front feet were so modified in eusauropods that individual digits would not have been visible in life. The arrangement of
9936-477: The size estimates of A. fragillimus may have been highly exaggerated. The longest dinosaur known from reasonable fossils material is probably Argentinosaurus huinculensis with length estimates of 35 metres (115 ft) to 36 metres (118 ft) according to the most recent researches. However the giant Barosaurus specimen BYU 9024 might have been even larger reaching lengths of 45–48 meters (148–157 ft). The longest terrestrial animal alive today,
10044-537: The size of the animal at 31 meters (102 ft) and 72 tonnes (79.4 short tons) based on the 1.75 meter (5.7 ft) long footprint. As massive quadrupeds , sauropods developed specialized "graviportal" (weight-bearing) limbs. The hind feet were broad, and retained three claws in most species. Particularly unusual compared with other animals were the highly modified front feet ( manus ). The front feet of sauropods were very dissimilar from those of modern large quadrupeds, such as elephants . Rather than splaying out to
10152-467: The surface of the water; in other words, they would float, and would not have been in danger of lung collapse due to water pressure when swimming. Evidence for swimming in sauropods comes from fossil trackways that have occasionally been found to preserve only the forefeet (manus) impressions. Henderson showed that such trackways can be explained by sauropods with long forelimbs (such as macronarians ) floating in relatively shallow water deep enough to keep
10260-657: The taxon would have been a sauropod related to Camarasaurus found nearby, both being large animals with lightly built vertebrae and solid limbs. Cope sold his collection of fossils to the American Museum of Natural History (AMNH) in 1895. Shortly before his death in 1897, he worked with the museum's artist Charles R. Knight to produce illustrations and paintings depicting some of his species in life, including Amphicoelias . Based on notes accompanying his sketches provided to Knight as reference material, Cope evidently considered both Amphicoelias and Brontosaurus junior synonyms of Camarasaurus supremus at this time. The specimen
10368-434: The tip, narrow at the neck) teeth. They had tiny heads, massive bodies, and most had long tails. Their hind legs were thick, straight, and powerful, ending in club-like feet with five toes, though only the inner three (or in some cases four) bore claws. Their forelimbs were rather more slender and typically ended in pillar-like hands built for supporting weight; often only the thumb bore a claw. Many illustrations of sauropods in
10476-413: The tooth affected how long it took for a new tooth to grow. Camarasaurus 's teeth took longer to grow than those for Diplodocus because they were larger. It was also noted by D'Emic and his team that the differences between the teeth of the sauropods also indicated a difference in diet. Diplodocus ate plants low to the ground and Camarasaurus browsed leaves from top and middle branches. According to
10584-415: The wide-set hip bones of titanosaurs ) or would have hindered rearing. For example, titanosaurs had an unusually flexible backbone, which would have decreased stability in a tripodal posture and would have put more strain on the muscles. Likewise, it is unlikely that brachiosaurids could rear up onto the hind legs, as their center of gravity was much farther forward than other sauropods, which would cause such
10692-433: The young reached adulthood. A 2014 study suggested that the time from laying the egg to the time of the hatching was likely to have been between 65 and 82 days. Exactly how segregated versus age-mixed herding varied across different groups of sauropods is unknown. Further examples of gregarious behavior will need to be discovered from more sauropod species to begin detecting possible patterns of distribution. Since early in
10800-603: Was coined by Othniel Charles Marsh in 1878, and is derived from Ancient Greek , meaning "lizard foot". Sauropods are one of the most recognizable groups of dinosaurs, and have become a fixture in popular culture due to their impressive size. Complete sauropod fossil finds are extremely rare. Many species, especially the largest, are known only from isolated and disarticulated bones. Many near-complete specimens lack heads, tail tips and limbs. Sauropods were herbivorous (plant-eating), usually quite long-necked quadrupeds (four-legged), often with spatulate (spatula-shaped: broad at
10908-474: Was defined as a node-based clade consisting of the most recent common ancestor of Dicraeosaurus and Diplodocus and all of its descendants. The word "Flagellicaudata" refers to long, whip-like tails of that animals ( flagellum is a Latin word meaning "whip" and cauda means in Latin "tail"). The phylogenetics of Diplodocoidea were reviewed in 2015 by Emanuel Tschopp, Octavio Mateus and Roger Benson with
11016-424: Was erected by Harris and Dodson (2004) for the diplodocoid clade formed by Dicraeosauridae and Diplodocidae in their paper describing a new genus of sauropod dinosaur, Suuwassea . The authors carried out a phylogenetic analysis and noted that Suuwassea , although more derived than Rebbachisauridae , is in a trichotomy with other families belonging to Diplodocoidea (Diplodocidae and Dicraeosauridae). Flagellicaudata
11124-411: Was given the accession number AMNH 5764, then including two dorsals, a pubis, a femur, a tooth , a scapula , coracoid and an ulna . While the forelimb material was not originally assigned to Amphicoelias , paleontologists Henry Fairfield Osborn and Charles Mook in 1921 added them to the holotype specimen on the basis that they were found in the same strata not far away, and bore differences from
11232-399: Was named in the same description as the type species, Amphicoelias altus . It was named for a series of four caudal vertebrae and a femur (AMNH 5765), in relatively good preservation. The caudals are bi-concave like the dorsals of A. altus , with short centra, long prezygapophyses and shallow pleurocoels. The femur is extremely robust, as well as being wide but short front-to-back. The femur
11340-474: Was not used often, and was synonymized with Diplodocoidea as the groups were often found to have the same content. In 2005, Mike P. Taylor and Darren Naish reviewed diplodocoid phylogeny and taxonomy, and realized that Diplodocimorpha could not be synonymized with Diplodocoidea. Whereas the former was defined node-based, the latter was branch-based. Haplocanthosaurus and possibly Amphicoelias are non-diplodocimorph diplodocoids. The clade Flagellicaudata
11448-469: Was once thought to be another distinguishing characteristic of Amphicoelias , it has since been found in some specimens of Diplodocus as well. Gregory S. Paul initially estimated A. altus to be similar in size to Diplodocus at 25 metres (82 ft) in length, but later moderated its size at 18 metres (59 ft) in length and 15 metric tons (17 short tons) in body mass. The dorsal vertebrae of Amphicoelias are partly incomplete, but their anatomy
11556-892: Was recognized early in the study of these animals, and, in fact, at least one sauropod specimen found in the 19th century ( Ornithopsis ) was originally misidentified as a pterosaur (a flying reptile) because of this. Some sauropods had armor . There were genera with small clubs on their tails, a prominent example being Shunosaurus , and several titanosaurs , such as Saltasaurus and Ampelosaurus , had small bony osteoderms covering portions of their bodies. A study by Michael D'Emic and his colleagues from Stony Brook University found that sauropods evolved high tooth replacement rates to keep up with their large appetites. The study suggested that Nigersaurus , for example, replaced each tooth every 14 days, Camarasaurus replaced each tooth every 62 days, and Diplodocus replaced each tooth once every 35 days. The scientists found qualities of
11664-442: Was the longest sauropod known from reasonably complete remains, but others, like the old record holder, Diplodocus , were also extremely long. The holotype (and now lost) vertebra of Amphicoelias fragillimus (now Maraapunisaurus ) may have come from an animal 58 metres (190 ft) long; its vertebral column would have been substantially longer than that of the blue whale. However, research published in 2015 speculated that
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