Maraapunisaurus
Maraapunisaurus | |
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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
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Binomial name | |
†Maraapunisaurus fragillimus | |
Synonyms | |
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Maraapunisaurus is a
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.
History of study
Original description
The
The
Disappearance of the specimen and quarry
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]
Modern interpretations
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
Description
Size
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
In 1994, using the related
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]
Classification
In 1921, Osborn and Mook placed A. fragillimus in the family Diplodocidae.
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]
Paleobiology
In his 2006 re-evaluation, Carpenter examined the
Paleoecology
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
See also
- Largest organisms
- Largest prehistoric animals
- Dinosaur size
- Breviparopus
- Bruhathkayosaurus
- Patagotitan
- Antarctosaurus
References
- ^ .
- ^ .
- ^ OCLC 1125972915.)
{{cite book}}
: CS1 maint: multiple names: authors list (link - S2CID 210840060.
- S2CID 210840060.
- ^ a b c d e f g h i j k Carpenter, K. (2006). "Biggest of the big: a critical re-evaluation of the mega-sauropod Amphicoelias fragillimus." In Foster, J.R. and Lucas, S.G., eds., 2006, Paleontology and Geology of the Upper Jurassic Morrison Formation. New Mexico Museum of Natural History and Science Bulletin 36: 131–138.
- ^ a b c McIntosh, John S. (1998). "New information about the Cope collection of sauropods from Garden Park, Colorado". Modern Geology. 23: 481–506.
- ^ a b
Cope, Edward Drinker (1878b). "A new species of Amphicoelias". doi:10.1086/272176.
- ^ Hay, Oliver Perry, 1902, Bibliography and Catalogue of the Fossil Vertebrata of North America, Governmental Printing Office, 868 pp
- ^ a b c Osborn, H.F.; Mook, C. C. (1921). "Camarasaurus, Amphicoelias and other sauropods of Cope". Memoirs of the American Museum of Natural History. New Series. 3 (3): 249–387.
- ^ Paul, G.S. (1994a). "Big sauropods — really, really big sauropods." The Dinosaur Report, The Dinosaur Society, Fall, p. 12–13.
- ^ a b "Assessment and Update Status Report on the Blue Whale Balaenoptera musculus" (PDF). Committee on the Status of Endangered Wildlife in Canada. 2002. Retrieved April 19, 2007.
- ^ Wedel, M. "SV-POW showdown: sauropods vs whales." [Weblog entry.] Sauropod Vertebra Picture of the Week. May 20, 2008. Accessed May 23, 2008.
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- S2CID 259782734.
- ^ Taylor, Mike (2018-10-21). "What if Amphicoelias fragillimus was a rebbachisaurid?". Sauropod Vertebra Picture of the Week. Archived from the original on 2018-10-22. Retrieved 2022-09-22.
- ^ Engelmann, G.F., Chure, D.J., and Fiorillo, A.R. (2004). "The implications of a dry climate for the paleoecology of the fauna of the Upper Jurassic Morrison Formation." In Turner, C.E., Peterson, F., and Dunagan, S.P., eds., Reconstruction of the extinct ecosystem of the Upper Jurassic Morrison Formation: Sedimentary Geology, 167: 297–308