Maraapunisaurus Temporal range: Late Jurassic, | |
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Original illustration, dating to c. 1878, of E. D. Cope's M. fragillimus specimen | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | Saurischia |
Clade: | † Sauropodomorpha |
Clade: | † Sauropoda |
Superfamily: | † Diplodocoidea |
Family: | † Rebbachisauridae |
Genus: | † Maraapunisaurus Carpenter, 2018 |
Species: | †M. fragillimus |
Binomial name | |
†Maraapunisaurus fragillimus | |
Synonyms | |
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Maraapunisaurus is a genus of sauropod dinosaur from the Late Jurassic Morrison Formation of western North America. Originally named Amphicoelias fragillimus, it has sometimes been estimated to be the largest dinosaur specimen ever discovered. Based on surviving descriptions of a single fossil bone, scientists have produced numerous size estimates over the years; the largest estimate M. fragillimus to have been the longest known animal at 58 metres (190 ft) in length with a mass of 150 tonnes (150 long tons; 170 short tons). However, because the only fossil remains were lost at some point after being studied and described in the 1870s, evidence survived only in contemporary drawings and field notes.
More recent studies have made a number of suggestions regarding the possibility of such an animal. One analysis of the surviving evidence, and the biological plausibility of such a large land animal, has suggested that the enormous size of this animal were over-estimates due partly to typographical errors in the original 1878 description. [1] More recently, it was suggested by paleontologist Kenneth Carpenter that the species is a rebbachisaurid, rather than a diplodocid sauropod. He therefore used Limaysaurus instead of Diplodocus as a basis for size estimates. This resulted in a smaller, 31-metre (102 ft) animal, and he dismissed the idea that there must have been typographical errors. [2] Since then, somewhat larger size estimates have been made, placing Maraapunisaurus at 70 [3] ―120 [4] tons in mass and 35–40 metres (115–131 ft) long, which still makes Maraapunisaurus the third longest animal to have ever lived behind Bruhathkayosaurus and - if one were to count extremely abnormal Barosaurus specimens - BYU 9024, as well as having the tallest and largest neural spine out of any animal (2.7-metre (8.9 ft)). [5] [3]
The holotype and only known specimen of Maraapunisaurus fragillimus was collected by Oramel William Lucas, shortly after he had been hired as a fossil collector by the renowned paleontologist Edward Drinker Cope, in 1877. Lucas discovered a partial vertebra (the neural arch including the spine) of a new sauropod species in Garden Park, north of Cañon City, Colorado, close to the quarry that yielded the first specimens of Camarasaurus . The vertebra was in poor condition, but astonishingly large. It was probably colored a very pale tan, tinted with maroon, like most fossils from the same area. [6] The preserved parts perhaps measured 1.5 meters (4.9 ft) in height; its original height might have been as tall as 2.7 meters (8.9 ft). [6] Lucas sent the specimen to Cope's house in Philadelphia in the spring or early summer of 1878, [7] and Cope published it as the holotype specimen of a new species in the genus Amphicoelias as A. fragillimus, that August. [8] In addition to this vertebra, Cope's 1879 field notes contain an entry for an "[i]mmense distal end of femur”, located only a few tens of meters away from the giant vertebra. [6] This specimen was never formally referred to the species. [2] Maraapunisaurus means 'huge reptile' based on maraapuni, the Southern Ute for 'huge'.[ citation needed ]
The specific name was chosen to express that the fossil was "very fragile", referring to the delicateness of the bone produced by very thin laminae (vertebral ridges). In 1902, Oliver Perry Hay hypercorrected the name to the Latin fragilissimus, [9] but such emendations are not allowed by the ICZN (International Code of Zoological Nomenclature). In any case, fragillimus is the correct superlative of fragilis in Latin. As revealed in Cope's notebooks, which he recorded based on Lucas' report on excavation site locations in 1879, the specimen came from a hill south of the Camarasaurus quarry now known as "Cope's Nipple", also sometimes known simply as "the Nipple" or "Saurian Hill". [2]
The gigantic vertebra has often been ignored in summaries of the largest dinosaurs partly because, according to subsequent reports, the whereabouts of both the vertebra and the femur are unknown, and all attempts to locate them have failed. [7] [10] Kenneth Carpenter, in 2006, presented a possible scenario for the disappearance of the specimen. As Cope noted in his description, the neural arch bone material was very fragile, and techniques to harden and preserve fossil bone had not yet been invented (Cope's rival, paleontologist Othniel Charles Marsh, was the first to use such resins, in the early 1880s). Carpenter observed that the fossil bones known from the quarry would have been preserved in deeply weathered mudstone, which tends to crumble easily and fragment into small, irregular cubes. Therefore, the bone may have crumbled badly and been discarded by Cope soon after he illustrated it in rear view for his paper. Carpenter suggested that this may explain why Cope drew the vertebra in only one view, rather than from multiple angles as he did for his other discoveries. [6]
In 2018, Carpenter recounted how Cope's collections were after his death sold to the American Museum of Natural History in 1897. While cataloging them, William Diller Matthew was unable to locate many important pieces, among them the holotype of A. fragillimus. Because of the possibility that it would turn up eventually, it was given the catalog number AMNH 5777. [2]
In 1994, an attempt was made to relocate the original quarry where the species and others had been found, using ground-penetrating radar to image bones still buried in the ground. The attempt failed because the fossilized mudstone bones were the same density as the surrounding rock, making it impossible to differentiate between the two. A study of the local topography also showed that the fossil-bearing rock strata were severely eroded, and probably were so when Lucas discovered M. fragillimus, suggesting that a majority of the skeleton had already disappeared when the vertebra was recovered. [6]
The giant proportions of the vertebra have been debated by paleontologists. Carpenter has argued that there is every reason to take Cope at his word, noting that the paleontologist's reputation was at stake. The discovery took place during the Bone Wars, and Cope's rival Marsh, who was "ever ready to humiliate" Cope, never called the claims into question. Marsh was known to have employed spies to monitor Cope's discoveries, and may have even had confirmation of the enormous size of the bones. [6] Paleontologists Henry Fairfield Osborn and C.C. Mook in 1921, as well as John S. McIntosh in 1998, also accepted Cope's data without question in published reviews. [7] [10] Other paleontologists have been more critical. In a 2015 analysis of the evidence and circumstances surrounding the publication and interpretation of the discovery, Cary Woodruff and John R. Foster concluded that the vertebra's size has been over-estimated and that modern paleontologists were accepting Cope's interpretation without due skepticism. They note that no comparably gigantic sauropod fossils have been discovered in the Morrison Formation or elsewhere, that 19th century paleontologists – including Cope himself – paid no attention to the size of fossil (even when it may have substantiated Cope's rule of size increase in animal lineages over time), and that typographical errors in his measurements – such as reporting vertebral measurements in meters rather than millimeters – undermine their reliability. It was suggested that the real height of the preserved specimen was just 138 centimeters (54 in). They concluded that the super-gigantic M. fragillimus is a "highly unlikely" creature based on unquestioning interpretation of Cope's report. [1]
In 2018, Carpenter once again defended the original measurements given by Cope in a paper re-describing the species based on Cope's illustration and description. The argument of a typographical error pointed to Cope's use of the abbreviation "m" rather than "mm" for millimeters, the same as used for meters, but Carpenter points out a capital "M" is used for meters, and that this was a standard method of abbreviation in the time period. In addition to this, he pointed to the communication between Lucas and Ferdinand Vandeveer Hayden, a survey geologist, where the large size was repeated without question. Lucas also often made his own specific measurements and annotated drawings of his fossils, so Carpenter considers it unlikely he would have been merely re-stating what Cope had said. Later, in 1880, Lucas included specific mention of the specimen in his autobiography, noting "[w]hat a monster the animal must have been," refuting the idea that no attention was given to the importance of the vertebra. Carpenter was critical of the typographical theory, saying: "It is unfortunate that they seek to disprove Cope’s claim by casting aspersions about the quality of his work and go so far as to alter Cope’s measurements." [2]
Upon studying the drawing of the specimen again, Carpenter found that it bore a strong resemblance to the vertebrae of rebbachisaurid diplodocoids; previously it had been allied with the type species of Amphicoelias, A. altus, as a diplodocid or primitive diplodocoid. Considering it to be a rebbachisaurid upon his re-examination, the species could not be referred to the genus Amphicoelias, and so he gave it a new generic name, Maraapunisaurus. Apparently, Carpenter was inspired by work of paleontology enthusiasts posted on the website DeviantArt; one user, Zachary Armstrong, known as "palaeozoologist" on the website, conjectured the same classification in 2014, four years before Carpenter's publication. He is credited in the acknowledgements of the paper. Naming a genus based on a lost specimen is rare, but he pointed out that the ICZN explicitly allows it, and the genus Nopcsaspondylus had been named in a similar fashion. The generic name is derived from the Southern Ute word "Ma-ra-pu-ni", meaning "huge", and the Latinised Greek saurus, meaning reptile. The name was suggested to Carpenter by the Southern Ute Cultural Department, based in Ignacio, Colorado. [2]
Any size estimate of M. fragillimus must be regarded with caution because of the lack of specimens and detailed, accurate documentation of its fossils. All size estimates are based on Cope's original description, which has somewhat vague measurements. It has also been suggested that it contains potentially critical typographical errors, but this idea has been disputed. [1] [2]
Producing an estimate of the complete size of M. fragillimus requires scaling the bones of better-described, closely related species based on the assumption that their relative proportions were similar. In his original paper, Cope did this while speculating on the size of a hypothetical M. fragillimus femur (upper leg bone). Cope stated that in other sauropod dinosaurs, specifically Amphicoelias altus and Camarasaurus supremus, the femora were always twice as tall as the tallest dorsal (back) vertebra, and estimated the size of an M. fragillimus femur to be 12 ft (3.6 m) tall. [8]
In 1994, using the related Diplodocus as a reference, Gregory S. Paul estimated a femur length of 3.1 to 4 meters (10 to 13 ft) for M. fragillimus. [11] The 2006 re-evaluation of M. fragillimus by Carpenter also used Diplodocus as a scale guide, finding a femur height of 4.3 to 4.6 meters (14 to 15 ft). [6] Carpenter went on to estimate the complete size of M. fragillimus, though he cautioned that relative proportions in diplodocids could vary from species to species. Assuming the same proportions as the well-known Diplodocus, Carpenter presented an estimated total length of 58 m (190 ft), which he noted fell within the range presented by Paul in 1994 (40 to 60 meters (130 to 200 ft)). Carpenter pointed out that even the lowest length estimates for A. fragillimus were higher than those for other giant sauropods, such as the diplodocid Supersaurus (32.5 meters (107 ft)), the brachiosaurid Sauroposeidon (34 meters (112 ft)), and the titanosaur Argentinosaurus (30 meters (98 ft)). Carpenter presented more speculative, specific proportions for M. fragillimus (again, based on a scaled-up Diplodocus), including a neck length of 16.75 meters (55.0 ft), a body length of 9.25 meters (30.3 ft), and a tail length of 32 meters (105 ft). He estimated the total forelimb height at 5.75 meters (18.9 ft) and hind limb height at 7.5 meters (25 ft), and the overall height (at the highest point on the back) at 9.25 meters (30.3 ft). [6] By comparison, the blue whale reaches 29.9 meters (98 ft) in length. [12]
When Carpenter redescribed the taxon as a rebbachisaurid instead of a diplodocid in 2018, he made new, very different, size estimates. As his classification scheme put it much farther away from Diplodocus taxonomically, he decided to use Limaysaurus as a model instead; among rebbachisaurids, it was chosen for its completeness because fossils of most other species (including other rebbachisaurids) are mostly fragmentary. Scaling up Limaysaurus directly, he estimated the length of Maraapunisaurus to be 30.3 metres (99 ft); additionally, he found it to be 7.95 metres (26.1 ft) tall at the hips and the vertebra to be 2.4 metres (7.9 ft). However, he noted that a study from a 2006 book calculated that the neck length of a sauropod scales with the length of the torso by a power of 1.35. With this in mind, he estimated Maraapunisaurus at a slightly longer 32 metres (105 ft). The neck of the animal in the smaller estimate was about 6 metres (20 ft) in length, whereas the larger scaled estimate found a neck of 7.6 metres (25 ft) in length. Overall, the revised length of the animal was around half of his earlier estimate, but still comparable to the other largest diplodocoids such as Supersaurus vivianae and Diplodocus hallorum. Also based on Limaysaurus, the complete femur was estimated to have been roughly 2.9 metres (9.5 ft) tall, significantly smaller than older estimates by Cope, Carpenter, and other subsequent authors. Finally, he estimated the length of the toes of the hindfoot, and thus the imprint surface, at 1.36 metres (4.5 ft), resulting in a foot similar in size to the animal that must have made the giant sauropods tracks in Broome, Australia. [2]
While M. fragillimus as a sauropod would be relatively elongated, its enormous size still made it very massive. Weight is much more difficult to determine than length in sauropods, as the more complex equations needed are prone to greater margins of error based on smaller variations in the overall proportions of the animal. Carpenter in 2006 used Paul's 1994 estimate of the mass of Diplodocus carnegii (11.5 metric tons (11.3 long tons; 12.7 short tons)) to speculate that M. fragillimus could have weighed up to 122.4 metric tons (120.5 long tons; 134.9 short tons). The heaviest blue whale on record weighed 190 metric tons (190 long tons; 210 short tons), [12] and the heaviest dinosaur known from reasonably good remains, Argentinosaurus, weighed 80 to 100 metric tons (79 to 98 long tons; 88 to 110 short tons), although if the size estimates can be validated, it could still be lighter than Bruhathkayosaurus , which has been estimated to have weighed 126 metric tons (124 long tons; 139 short tons), but is also known from highly fragmentary remains. [13]
In 2019, Gregory S. Paul discovered that Calvo and Salgado's (1995) measurements of Limaysaurus tessonei were inconsistent with those of the measurements using scale bars, and ratios of bones like the humerus to the femur were higher or lower than stated. This later contributed to Carpenter 2018's estimate being smaller than expected. Thus, he estimated Maraapunisaurus at 35–40 m (115–131 ft) in length and 80–120 t (88–132 short tons) in weight. He estimates a femoral length of 3–3.5 m (9.8–11.5 ft) and a dorsal-sacral length of 7.7–9 m (25–30 ft), much longer than those of the largest titanosaurs. This is larger than Carpenter's estimation, and he stated that the known vertebra could not be plausibly accommodated within a sauropod smaller than 35 m (115 ft). He even states that Maraapunisaurus is possibly one of the largest land animal known. He also said that there was the possibility that Maraapunisaurus had more typical body proportions for a sauropod. In this case, it would be even larger than estimated, but he also says that this possibility is less likely. [14] On the other hand, Molina-Pérez and Larramendi in 2020 estimated Maraapunisaurus at 35 m (115 ft) and 70 t (77 short tons) with a hip height of 7.7 m (25 ft), much smaller and lighter than Paul's estimation. [3]
Nevertheless, if the recent estimations of Bruhathkayosaurus was any indication, Maraapunisaurus would have been the second largest animal to walked the earth and the fourth largest animal overall. [15]
In 1921, Osborn and Mook placed A. fragillimus in the family Diplodocidae. [10] This was generally accepted until well into the twenty-first century. In 2018, Carpenter concluded from a qualitative anatomical comparison that the species was a basal member of the Rebbachisauridae, and assigned it the new name Maraapunisaurus, after a Southern Ute word maraapuni meaning "huge". [16] The basal position would be indicated by the presence of a hyposphene, a secondary rear articulation process, which is a trait shared with the basal rebbachisaurids Histriasaurus , Comahuesaurus and Demandasaurus . Although Maraapunisaurus is older than Histriasaurus, in some ways, it is more derived than Histriasaurus as shown by the extensive pneumatisation and the tall neural arch base. [2]
If Maraapunisaurus belongs to Rebbachisauridae, it would be the oldest member of its group known and the only one discovered from the Jurassic. The previous oldest one was Xenoposeidon . It would also be the only one from North America. Carpenter concluded that the Rebbachisauridae might have originated from that continent and only later spread to Europe; from there they would have invaded Africa and South America. The usual interpretation had been that rebbachisaurids were South American in origin, thus if Maraapunisaurus was a rebbachisaurid, the migration of the rebbachisaurids over time would be the reverse of the original interpretation. [2]
In his 2006 re-evaluation, Carpenter examined the paleobiology of giant sauropods, including Maraapunisaurus, and addressed the question of why the group attained such a large 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 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. [6]
Throughout their evolutionary history, sauropod dinosaurs were found primarily in semi-arid, seasonally dry environments, with a corresponding seasonal drop in the quality of food during the dry season. The environment of Maraapunisaurus 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. [6]
The Morrison Formation environment in which Maraapunisaurus lived would have resembled a modern savanna, though since grasses did not appear until the Late Cretaceous, ferns were probably the dominant plant and main food source for Maraapunisaurus. Though Engelmann et al. (2004) dismissed ferns as a sauropod food source due to their relatively low caloric content, [17] Carpenter argued that the sauropod digestive system, well adapted to handle low-quality food, allows for the consumption of ferns as 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 Maraapunisaurus may have used the shade of the gallery forests to stay cool during the day, and done most of their feeding on the open savanna at night. [6]
Apatosaurus is a genus of herbivorous sauropod dinosaur that lived in North America during the Late Jurassic period. Othniel Charles Marsh described and named the first-known species, A. ajax, in 1877, and a second species, A. louisae, was discovered and named by William H. Holland in 1916. Apatosaurus lived about 152 to 151 million years ago (mya), during the late Kimmeridgian to early Tithonian age, and are now known from fossils in the Morrison Formation of modern-day Colorado, Oklahoma, New Mexico, Wyoming, and Utah in the United States. Apatosaurus had an average length of 21–23 m (69–75 ft), and an average mass of 16.4–22.4 t. A few specimens indicate a maximum length of 11–30% greater than average and a mass of approximately 33 t.
Argentinosaurus is a genus of giant sauropod dinosaur that lived during the Late Cretaceous period in what is now Argentina. Although it is only known from fragmentary remains, Argentinosaurus is one of the largest known land animals of all time, perhaps the largest, measuring 30–35 metres (98–115 ft) long and weighing 65–80 tonnes. It was a member of Titanosauria, the dominant group of sauropods during the Cretaceous. It is widely regarded by many paleontologists as the biggest dinosaur ever, and perhaps lengthwise the longest animal ever, though both claims have no concrete evidence yet.
Supersaurus is a genus of diplodocid sauropod dinosaur that lived in North America during the Late Jurassic period. The type species, S. vivianae, was first discovered by Vivian Jones of Delta, Colorado, in the middle Morrison Formation of Colorado in 1972. The fossil remains came from the Brushy Basin Member of the formation, dating between 153 to 145 million years ago. It was a very large sauropod, with the WDC and BYU specimens reaching 33–35 meters (108–115 ft) in length and approximately 35–40 metric tons in body mass. A potential second species, S. lourinhanensis (Dinheirosaurus), is known from Portugal and has been dated to a similar time.
Sauropoda, whose members are known as sauropods, is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads, 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.
Giganotosaurus is a genus of theropod dinosaur that lived in what is now Argentina, during the early Cenomanian age of the Late Cretaceous period, approximately 99.6 to 95 million years ago. The holotype specimen was discovered in the Candeleros Formation of Patagonia in 1993 and is almost 70% complete. The animal was named Giganotosaurus carolinii in 1995; the genus name translates to "giant southern lizard", and the specific name honors the discoverer, Ruben Carolini. A dentary bone, a tooth, and some tracks, discovered before the holotype, were later assigned to this animal. The genus attracted much interest and became part of a scientific debate about the maximum sizes of theropod dinosaurs.
Camarasaurus was a genus of quadrupedal, herbivorous dinosaurs and is the most common North American sauropod fossil. Its fossil remains have been found in the Morrison Formation, dating to the Late Jurassic epoch, between 155 and 145 million years ago.
Sauroposeidon is a genus of sauropod dinosaur known from several incomplete specimens including a bone bed and fossilized trackways that have been found in the U.S. states of Oklahoma, Wyoming, and Texas.
Bruhathkayosaurus is a controversial genus of sauropod dinosaur found in the Kallamedu Formation of India. The fragmentary remains were originally described as a theropod, but it was later determined to be a titanosaurian sauropod. Length estimates by researchers exceed those of the titanosaur Argentinosaurus, as longer than 35 metres (115 ft) and weighing over 80 tonnes. A 2023 estimate placed Bruhathkayosaurus as potentially weighing approximately 110–170 tonnes. If the upper estimates of the 2023 records are accurate, Bruhathkayosaurus may have rivalled the blue whale as one of the largest animals to ever exist. However, all of the estimates are based on the dimensions of the fossils described in Yadagiri and Ayyasami (1987), and in 2017, it was reported that the holotype fossils had disintegrated and no longer exist.
Barosaurus was a giant, long-tailed, long-necked, plant-eating sauropod dinosaur closely related to the more familiar Diplodocus. Remains have been found in the Morrison Formation from the Upper Jurassic Period of Utah and South Dakota. It is present in stratigraphic zones 2–5.
Antarctosaurus is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous Period of what is now South America. The type species, Antarctosaurus wichmannianus, and a second species, Antarctosaurus giganteus, were described by prolific German paleontologist Friedrich von Huene in 1929. Three additional species of Antarctosaurus have been named since then but later studies have considered them dubious or unlikely to pertain to the genus.
Size is an important aspect of dinosaur paleontology, of interest to both the general public and professional scientists. Dinosaurs show some of the most extreme variations in size of any land animal group, ranging from tiny hummingbirds, which can weigh as little as two grams, to the extinct titanosaurs, which could weigh as much as 50–100 t.
Breviparopus is the name given to an ichnogenus of dinosaur, having been made by an unknown genus of sauropod. As an ichnogenus, the taxon is represented by a 90-metre (295 ft) long series of fossil tracks, or ichnites, found in the spring of 1979 in the Atlas Mountains of present-day Morocco. At the time, this area would have been part of the splitting Gondwana supercontinent. The animal that produced the Breviparopus tracks is rumored to be one of the largest dinosaurs, though its exact size has been the subject of much debate.
Camarasaurus supremus is a species of sauropod dinosaur that lived during the Jurassic period in what is now the western United States. It is the type species of Camarasaurus, which also includes the species Camarasaurus grandis, Camarasaurus lentus, and Camarasaurus lewisi. C. supremus was discovered by the paleontologist Edward Drinker Cope in 1877, at the outset of the Bone Wars, a period of scientific competition between Cope and his rival Othniel Marsh. C. supremus is the largest and geologically youngest species in its genus, and was contemporary with several other exceptionally large dinosaurs, such as Saurophaganax and Maraapunisaurus. Despite being the first discovered species of Camarasaurus, C. supremus is relatively rare and poorly known.
Apatosaurinae is a subfamily of diplodocid sauropods, an extinct group of large, quadrupedal dinosaurs, the other subfamily in Diplodocidae being Diplodocinae. Apatosaurines are distinguished by their more robust, stocky builds and shorter necks proportionally to the rest of their bodies. Several fairly complete specimens are known, giving a comprehensive view of apatosaurine anatomy.
Amphicoelias is a genus of herbivorous sauropod dinosaur that lived approximately 150 million years ago during the Tithonian of what is now Colorado, United States. Amphicoelias was moderately sized at about 18 metres (59 ft) in length and 15 metric 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.
Diplodocus was a genus of diplodocid sauropod dinosaurs, whose fossils were first discovered in 1877 by S. W. Williston. The generic name, coined by Othniel Charles Marsh in 1878, is a Neo-Latin term derived from Greek διπλός (diplos) "double" and δοκός (dokos) "beam", in reference to the double-beamed chevron bones located in the underside of the tail, which were then considered unique.
Brachiosaurus is a genus of sauropod dinosaur that lived in North America during the Late Jurassic, about 154 to 150 million years ago. It was first described by American paleontologist Elmer S. Riggs in 1903 from fossils found in the Colorado River valley in western Colorado, United States. Riggs named the dinosaur Brachiosaurus altithorax; the generic name is Greek for "arm lizard", in reference to its proportionately long arms, and the specific name means "deep chest". Brachiosaurus is estimated to have been between 18 and 22 meters long; body mass estimates of the subadult holotype specimen range from 28.3 to 46.9 metric tons. It had a disproportionately long neck, small skull, and large overall size, all of which are typical for sauropods. Atypically, Brachiosaurus had longer forelimbs than hindlimbs, which resulted in a steeply inclined trunk, and a proportionally shorter tail.
Nigersaurus is a genus of rebbachisaurid sauropod dinosaur that lived during the middle Cretaceous period, about 115 to 105 million years ago. It was discovered in the Elrhaz Formation in an area called Gadoufaoua, in Niger. Fossils of this dinosaur were first described in 1976, but it was only named Nigersaurus taqueti in 1999, after further and more complete remains were found and described. The genus name means "Niger reptile", and the specific name honours the palaeontologist Philippe Taquet, who discovered the first remains.
Paralititan was a giant titanosaurian sauropod dinosaur genus discovered in coastal deposits in the Upper Cretaceous Bahariya Formation of Egypt. It lived between 99.6 and 93.5 million years ago.
Sidersaura is an extinct genus of rebbachisaurid sauropod dinosaur from the Late Cretaceous Huincul Formation of Argentina. The genus contains a single species, S. marae, known from the remains of four individuals. Sidersaura represents one of the largest known rebbachisaurids.
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