Argentinosaurus

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Argentinosaurus
Temporal range: Late Cretaceous, 97–93.5 Ma
Argentinosaurus skeleton, PLoS ONE.png
Reconstructed skeleton, Museo Municipal Carmen Funes, Plaza Huincul, Argentina
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder: Sauropodomorpha
Clade: Sauropoda
Clade: Titanosauria
Clade: Lithostrotia
Clade: Lognkosauria
Genus: Argentinosaurus
Bonaparte & Coria, 1993
Type species
Argentinosaurus huinculensis

Argentinosaurus (meaning "Argentine lizard") is a genus of titanosaur sauropod dinosaur first discovered by Guillermo Heredia in Argentina. The generic name refers to the country in which it was discovered. The dinosaur lived on the then-island continent of South America somewhere between 97 and 93.5 million years ago,[1] during the Late Cretaceous Period. It is among the largest known dinosaurs.

Description[edit]

Hypothetical life restoration

Not much of Argentinosaurus has been recovered. The holotype (specimen number, PVPH-1) included only a series of vertebrae (six from the back, five partial vertebrae from the hip region), ribs of the right side of the hip region, a part of a rib from the flank, and the right fibula (lower leg bone). One of these vertebrae was 1.59 meters tall, and the fibula was about 1.55 meters (61 inches).[2] In addition to these bones, an incomplete femur (upper leg bone, specimen number MLP-DP 46-VIII-21-3) is assigned to Argentinosaurus; this incomplete femur shaft has a minimum circumference of about 1.18 meters. The completed femur is estimated at around 2.5m long.[3] By comparison, there are complete femurs preserved in other giant titanosaurs; Antarctosaurus giganteus which measures 2.35m, and Patagotitan mayorum which measures 2.38m.[3][4]

Size[edit]

Skeletal reconstruction, holotype material in white, referred femoral shaft in green

The proportions of the known bones and comparisons with other sauropod relatives allow paleontologists to estimate the size of Argentinosaurus. A reconstruction by Gregory S. Paul in 1994 estimated Argentinosaurus at between 30–35 metres (98–115 ft) in length and with a weight of up to 80–100 tonnes (88–110 short tons).[5][6] In 2016, Paul listed Argentinosaurus at 30 metres (98 ft) in length but with a lower weight estimate of 50+ tonnes.[7] The skeletal mount of Argentinosaurus in Museo Carmen Funes is 39.7 metres (130 ft) long and 7.3 metres (24 ft) tall at the shoulder. This is the longest reconstruction in a museum and contains the original material, including a mostly complete fibula.[8] Other estimates have compared the fragmentary material to relatively complete titanosaurs to help estimate the size of Argentinosaurus. In 2006, Carpenter used the more complete Saltasaurus as a guide and estimated Argentinosaurus at 30 metres (98 ft) in length.[9] An unpublished estimate used published reconstructions of Saltasaurus, Opisthocoelicaudia, and Rapetosaurus as guides and gave shorter length estimates of between 22–26 metres (72–85 ft).[10] Weight estimates are less common, but in 2004, Mazzetta and colleagues provided a range of 60–88 tonnes (66–97 short tons), and considered 73 tonnes (80 short tons) to be the most likely, making it the heaviest sauropod known from good material.[3] In 2013, Sellers and Colleagues estimated a mass of 83.2 tonnes (91.7 short tons) by calculating the volume of the aforementioned Museo Carmen Funes skeleton.[8] In 2014, Benson and colleagues estimated the mass of Argentinosaurus at 90 tonnes (99 short tons).[11] In 2013, Scott Hartman suggested that since Argentinosaurus is a basal titanosaur, it would have a shorter tail and narrower chest than Puertasaurus, suggesting that it was slightly smaller than other giant titanosaurs such as Puertasaurus and Alamosaurus.[12]

Discovery[edit]

Dorsal vertebra

The first fossils identified as Argentinosaurus were found in 1989 by a rancher in Argentina, who mistook the leg for a giant piece of petrified wood. A gigantic vertebra, approximately the size of a man, was also found.[2]

The type and only species, A. huinculensis, was described and published in 1993 by the Argentine palaeontologists José F. Bonaparte and Rodolfo Coria. It lived approximately 96 to 94 million years ago, during the late Cenomanian stage of the Upper Cretaceous period. The fossil discovery site is in the Huincul Formation of the Río Limay Subgroup in Neuquén Province, Argentina (the Huincul Formation was a member of the Río Limay Formation according to the naming of the time).[2]

Etymology[edit]

The generic name of Argentinosaurus huinculensis means "Argentine lizard." The specific name refers to Plaza Huincul, the town that the holotype specimen was discovered in.[2]

Classification[edit]

Mounted skeleton of the related genus Patagotitan

Argentinosaurus is a titanosaurian sauropod. Bonaparte and Coria classified it in Andesauridae in 1993.[2] In 1997, Salgado and colleagues found Argentinosaurus to belong to Titanosauridae, in an unnamed clade with Opisthocoelicaudia and an indeterminate titanosaur.[13] A 2003 study by Wilson and Upchurch found both Andesauridae and Titanosauridae to be invalid.[14] A 2011 study by Mannion and Calvo also found Andesauridae to be paraphyletic and recommended its disuse.[15] In 2002, Argentinosaurus was recovered as a member of Titanosauria by Pisani and colleagues, and again found to be in a clade with Opisthocoelicaudia and an unnamed taxon, in addition to Lirainosaurus.[16] In 2014, Kenneth Lacovara and colleagues found Argentinosaurus to be a titanosaur that was not a member of Lithostrotia.[17] In 2016, González-Riga and colleagues also found it to be a basal titanosaur outside of Lithostrotia.[18] A 2017 study by Carballido and colleagues recovered it as a member of Lognkosauria and the sister taxon of Patagotitan.[4] In 2018, González Riga and colleagues also found it to belong in Lognkosauria.[19] Another 2018 study by Averianov and Efimov also found it to belong to Lognkosauria.[20]

The following cladogram shows the position of Argentinosaurus in Lognkosauria according to González Riga and colleagues, 2018.[19]


Lognkosauria

Mendozasaurus

Futalognkosaurus

Argentinosaurus

Notocolossus

Patagotitan

Puertasaurus

Paleobiology[edit]

Biomechanics and speed[edit]

A video showing Argentinosaurus walking as estimated by computer simulations.

In 2013, in a study published in PLoS ONE on October 30, 2013 by Dr. Bill Sellers, Dr. Rodolfo Coria, Lee Margetts and colleagues, Argentinosaurus was digitally reconstructed to test its locomotion for the first time. Before computer simulations, the most common way of estimating speed was through studying bone histology and ichnology. Commonly, studies about sauropod bone histology and speed focus on 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.[8]

Argentinosaurus femur, Museo de La Plata.

To estimate the gait and speed of Argentinosaurus, the study performed a musculoskeletal analysis combined with computer simulations. Similar analyses have previously been conducted on hominids, terror birds, and other dinosaurs. To conduct the analysis, the team had to create a digital skeleton of the animal in question, estimate the muscles and their properties, and estimate the weight and how it's distributed. Then using computer simulation and genetic algorithms, which could be optimised for metabolic energy cost or speed, the digital Argentinosaurus learns to walk. The study estimated that their 83 tonne sauropod model was mechanically competent at a top speed of 2 m/s (5 mph) but was approaching a functional limit. The study concluded that much larger terrestrial vertebrates might be possible, but would require significant body remodeling and possibly behavioral change to prevent joint collapse.[8][21] The authors of the study noted that there are areas of the model that can be improved with future research, such as, gathering more data from living animals to improve the soft tissue reconstruction, using more complete sauropod specimens to confirm the studies findings, and performing sensitivity analysis.[8]

Paleoecology[edit]

Skeletal mounts of Mapusaurus roseae, a large carnivore from the Huincul Formation

Argentinosaurus was discovered in the Argentine Province of Neuquén. It was originally reported from the Huincul Group of the Río Limay Formation.[2] More recently, the units have been referred to as the Huincul Formation and the Río Limay Subgroup, the latter of which is a subdivision of the Neuquén Group. The Huincul Formation is composed of yellowish and greenish sandstones of fine to medium grain, some of which are tuffaceous. These deposits likely come from the Late Cenomanian age.[22]

In addition to Argentinosaurus, the Huincul Formation has yielded several other dinosaurs. These include other sauropods like the rebbachisaurid Cathartesaura[23] and the titanosaur Choconsaurus.[24] Theropods, including carcharodontosaurids such as Mapusaurus[25] and Taurovenator, abelisauroids such as Skorpiovenator[26] and Ilokelesia, unenlagiines, and other theropods such as Aoniraptor and Gualicho[27] have also been discovered there.[28] Several iguanodonts have also been found in the Huincul Formation, including Gasparinisaura and some others that have not been identified.[29][22]

References[edit]

  1. ^ Holtz, Thomas R. Jr. (2012) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages, Winter 2011 Appendix, p. 36.
  2. ^ a b c d e f Bonaparte J, Coria R (1993). "Un nuevo y gigantesco sauropodo titanosaurio de la Formacion Rio Limay (Albiano-Cenomaniano) de la Provincia del Neuquen, Argentina". Ameghiniana (in Spanish). 30 (3): 271–282.
  3. ^ a b c Mazzetta, Gerardo V.; Christiansen, Per; Fariña, Richard A. (2004). "Giants and Bizarres: Body Size of Some Southern South American Cretaceous Dinosaurs" (PDF). Historical Biology. 16 (2–4): 71–83. CiteSeerX 10.1.1.694.1650. doi:10.1080/08912960410001715132. Retrieved January 8, 2008.
  4. ^ a b Carballido, José L.; et al. (2017). "A new giant titanosaur sheds light on body mass evolution among sauropod dinosaurs". Proc. R. Soc. B. 284 (1860): 20171219. doi:10.1098/rspb.2017.1219. PMC 5563814. PMID 28794222.
  5. ^ Paul, Gregory S. (Autumn 1994). "Big Sauropods - Really, Really Big Sauropods" (PDF). The Dinosaur Report: 12–13. Retrieved November 14, 2011.
  6. ^ Paul, Gregory S. (1997). "Dinosaur models: the good, the bad, and using them to estimate the mass of dinosaurs". In Wolberg, D. L.; Stump, E.; Rosenberg, G. D. (eds.). DinoFest International Proceedings. The Academy of Natural Sciences. pp. 129–154.
  7. ^ S., Paul, Gregory (October 25, 2016). The Princeton field guide to dinosaurs (2nd ed.). Princeton, N.J. ISBN 9781400883141. OCLC 954055249.
  8. ^ a b c d e Sellers, W. I.; Margetts, L.; Coria, R. A. B.; Manning, P. L. (2013). Carrier, David (ed.). "March of the Titans: The Locomotor Capabilities of Sauropod Dinosaurs". PLoS ONE. 8 (10): e78733. Bibcode:2013PLoSO...878733S. doi:10.1371/journal.pone.0078733. PMC 3864407. PMID 24348896.
  9. ^ Carpenter, Kenneth (2006). "Biggest of the Big: A Critical Re-Evaluation of the Mega-Sauropod Amphicoelias fragillimus Cope, 1878" (PDF). In Foster, John R.; Lucas, Spencer G. (eds.). Paleontology and Geology of the Upper Jurassic Morrison Formation. 36. New Mexico Museum of Natural History and Science Bulletin. pp. 131–138.
  10. ^ Mortimer, Mickey (September 12, 2001). "Titanosaurs too Large?". Dinosaur Mailing List. Retrieved January 8, 2009.
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  12. ^ "The biggest of the big".
  13. ^ Salgado, Leonardo; Coria, Rodalpho Anibal; Calvo, Jorge Orlando. "Evolution of titanosaurid sauropods I.: Phylogenetic analysis based on the postcranial evidence". Ameghiniana. 34 (1): 3–32.
  14. ^ Wilson, Jeffrey A.; Upchruch, Paul. "A revision of Titanosaurus Lydekker (Dinosauria ‐ Sauropoda), the first dinosaur genus with a 'Gondwanan' distribution" (PDF). Journal of Systematic Palaeontology. 1 (3): 125–160.
  15. ^ Mannion, Philip D.; Calvo, Jorge O. (2011). "Anatomy of the basal titanosaur (Dinosauria, Sauropoda) Andesaurus delgadoi from the mid-Cretaceous (Albian–early Cenomanian) Río Limay Formation, Neuquén Province, Argentina: implications for titanosaur systematics" (PDF). Zoological Journal of the Linnean Society. 163 (1): 155–181. doi:10.1111/j.1096-3642.2011.00699.x.
  16. ^ Pisani, Davide; Yates, Adam M.; Langer, Max C.; Benson, Michael J. (2002). "A genus-level supertree of the Dinosauria" (PDF). Proceedings of the Royal Society of London. Series B: Biological Sciences. 269 (1494): 915–921.
  17. ^ Lacovara, Kenneth J.; Ibiricu, L.M.; Lamanna, M.C.; Poole, J.C.; Schroeter, E.R.; Ullmann, P.V.; Voegele, K.K.; Boles, Z.M.; Egerton, V.M.; Harris, J.D.; Martínez, R.D.; Novas, F.E. (September 4, 2014). "A Gigantic, Exceptionally Complete Titanosaurian Sauropod Dinosaur from Southern Patagonia, Argentina". Scientific Reports. 4: 6196. Bibcode:2014NatSR...4E6196L. doi:10.1038/srep06196. PMC 5385829. PMID 25186586.
  18. ^ González Riga, Bernardo J.; Lamanna, Matthew C.; Ortiz David, Leonardo D.; Calvo, Jorge O.; Coria, Juan P. (2016). "A gigantic new dinosaur from Argentina and the evolution of the sauropod hind foot". Scientific Reports. 6: 19165. Bibcode:2016NatSR...619165G. doi:10.1038/srep19165. ISSN 2045-2322. PMC 4725985. PMID 26777391.
  19. ^ a b Gonzalez Riga, B.J.; Mannion, P.D.; Poropat, S.F.; Ortiz David, L.; Coria, J.P. (2018). "Osteology of the Late Cretaceous Argentinean sauropod dinosaur Mendozasaurus neguyelap: implications for basal titanosaur relationships". Journal of the Linnean Society. 184 (1): 136–181. doi:10.1093/zoolinnean/zlx103. hdl:10044/1/53967.
  20. ^ Averianov, Alexander; Efimov, Vladimir (2018). "The oldest titanosaurian sauropod of the Northern Hemisphere". Biological Communications. 63 (6): 145–162. doi:10.21638/spbu03.2018.301.
  21. ^ "Argentinosaurus"
  22. ^ a b Leanza, Héctor A.; et al. (2004). "Cretaceous terrestrial beds from the Neuquén Basin (Argentina) and their tetrapod assemblages". Cretaceous Research. 25 (1): 61–87. doi:10.1016/j.cretres.2003.10.005.
  23. ^ de Jesus Faria, Caio César; et al. (2015). "Cretaceous sauropod diversity and taxonomic succession in South America" (PDF). Journal of South American Earth Sciences. 61: 154–163. Bibcode:2015JSAES..61..154D. doi:10.1016/j.jsames.2014.11.008.
  24. ^ SimóN, Edith; Salgado, Leonardo; Calvo, Jorge O. (2017). "A new titanosaur sauropod from the Upper Cretaceous of Patagonia, Neuquén Province, Argentina". Ameghiniana. 55 (1): 1–29. doi:10.5710/AMGH.01.08.2017.3051.
  25. ^ Coria, Rodolfo A.; Currie, Philip J. (2006). "A new carcharodontosaurid (Dinosauria, Theropoda) from the Upper Cretaceous of Argentina". Geodiversitas. 28 (1): 71–11.
  26. ^ Canale, Juan I.; et al. (2009). "New carnivorous dinosaur from the Late Cretaceous of NW Patagonia and the evolution of abelisaurid theropods". Naturwissenschaften. 96 (3): 409–14. Bibcode:2009NW.....96..409C. doi:10.1007/s00114-008-0487-4. PMID 19057888.
  27. ^ Apesteguía, S; Smith, ND; Juárez Valieri, R; Makovicky, PJ (2016). "An Unusual New Theropod with a Didactyl Manus from the Upper Cretaceous of Patagonia, Argentina". PLoS ONE. 11 (7): e0157793. Bibcode:2016PLoSO..1157793A. doi:10.1371/journal.pone.0157793. PMC 4943716. PMID 27410683.
  28. ^ Motta, Matías J.; et al. (2016). "New theropod fauna from the Upper Cretaceous (Huincul Formation) of northwestern Patagonia, Argentina". Cretaceous Period: Biotic Diversity and Biogeography. New Mexico Museum of Natural History and Science, Bulletin. 71: 231–253.
  29. ^ Coria, Rodolfo A.; Calvo, Jorge O. (2002). "A new iguanodontian ornithopod from Neuquén Basin, Patagonia, Argentina". Journal of Vertebrate Paleontology. 22 (3): 503–509. doi:10.1671/0272-4634(2002)022[0503:ANIOFN]2.0.CO;2.

External links[edit]