Antarctosaurus
| Antarctosaurus | ||||||||||||
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Femur bone of Antarctosaurus wichmannianus , exhibited in the Museo de la Plata ( Argentina ) |
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| Temporal occurrence | ||||||||||||
| Upper Cretaceous (Lower Campanium ) | ||||||||||||
| 83.6 to 80.6 million years | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Antarctosaurus | ||||||||||||
| Huene , 1929 | ||||||||||||
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Antarctosaurus is a genus of sauropod dinosaur from the group of Titanosauria .
So far, a fragmentary skeleton is known that comes from the Upper Cretaceous (early Campanium ) Argentina and consists of parts of the skull and the remaining skeleton. This skeleton was discovered in 1916 and described scientifically for the first time in 1929 by the German paleontologist Friedrich von Huene . Huene named Antarctosaurus wichmannianus as the type species . In the same year von Huene described another species, which he named Antarctosaurus giganteus because of the gigantic size of the bones .
Since then, three more species have been described from India , Kazakhstan, and Brazil , but none of them actually belong to Antarctosaurus , as later studies showed .
The name Antarctosaurus ( Greek ant- (anti) - "opposite", arktos - "north", saura - "lizard") means something like "lizard across from the north" and points to the location in South America, a continent of the southern Hemisphere. Although the name has the same origin as the name Antarctica , it does not refer to this continent.
Systematics
The systematic position of Antarctosaurus wichmannianus has been controversial since it was first described by von Huene. Von Huene thought this genus was a titanosaur, but found that the skull and especially the jawbones and teeth showed clear similarities with Diplodocidae such as Diplodocus : the teeth were pin-like and inclined forward, while the rows of teeth were short and on the foremost section of the Jaws were restricted. Werner Janensch (1929) assumed on the basis of these findings that the Titanosauridae and the Diplodocidae were closely related - this hypothesis was only questioned in the late 1990s. After its first description, Antarctosaurus wichmannianus was classified by various authors either within the Titanosauridae or, based on the features of the skull, within the Diplodocoidea. To make matters worse, it is not clear whether the skull and the remaining skeleton actually belong to the same individual, as von Huene suspected, since the location of the bones is not documented. Today it is assumed that the skulls of titanosaurs and diplodocoids developed a similar morphology ( convergent evolution ) independently of one another . The titanosaurs are now considered relatives of the Brachiosauridae and are classified within the Macronaria .
There is now a consensus that Antarctosaurus belongs to the Titanosauria. Upchurch and colleagues (2004) suspect that it was a derived (modern) titanosaur within the Lithostrotia . Wilson (2005) classified Antarctosaurus within the Nemegtosauridae , along with genera such as Nemegtosaurus , Quaesitosaurus, and Rapetosaurus .
Research history and species
Antarctosaurus wichmannianus
Antarctosaurus wichmannianus is the type species and the only Antarctosaurus species that is recognized as valid. The fragmentary skeleton was discovered in 1916 by Wichmann near General Roca in the Argentine province of Río Negro , the rocks of the site belong stratigraphically to the Río-Colorado formation . Friedrich von Huene examined the remains between 1923 and 1926 in Buenos Aires and described them as Antarctosaurus in 1929 ; the epithet wichmannianus honors Wichmann, the finder of the skeleton.
The find includes the posterior section of the skull including the almost complete skull , isolated jaw fragments and other isolated skull bones, including the scaly bone (squamosum), the parietal bone, the square bone (squares) and the frontal bone . Remnants of the residual skeleton include a cervical vertebrae, caudal vertebrae, ribs, scapula (scapula), parts of the right front leg including a fragmentary humerus (humerus), parts of Elle (ulna) and spoke (radius) as well as a fragmentary hand skeleton, pelvic bones, including partial iliac (Ilium ), ischium (ischium) and partial pubis (pubic), and the left hind leg including the thigh bone (femur), tibia (tibia) anklebone (Astragalus), the heel bone (calcaneus) and metatarsal bones with a.
Antarctosaurus giganteus
After describing the genus Antarctosaurus with the type species Antarctosaurus wichmannianus , von Huene described another species in the same year, which he named Antarctosaurus giganteus because of its enormous size . This species is known only from very fragmentary remains and is considered by many researchers as the noun dubium (dubious name). Finds come from the Río Neuquén Formation in the Argentine province of Neuquén and are dated to the late Coniacian to early Santonian .
The most famous bones of Antarctosaurus giganteus are two huge thigh bones (femora), the longest of which is 2.35 meters. This makes Antarctosaurus giganteus one of the largest known sauropods. Researchers working with Gerardo Mazzetta (2004) estimate the weight of this species at 69 tons, while the type species Antarctosaurus wichmannianus is estimated at 34 tons.
"Antarctosaurus" septentrionalis (= Jainosaurus )
In 1933 Huene and Matley described another Antarctosaurus species from the Lameta Formation of India - Antarctosaurus septentrionalis . Today these remains are attributed to a separate genus, Jainosaurus .
"Antarctosaurus" jaxartensis
The Soviet palaeontologist Anatoly Riabinin named this species in 1939 based on an isolated thigh bone from Kazakhstan. Now used as the noun dubium , there is a high probability that this bone does not belong to Antarctosaurus .
"Antarctosaurus" brasiliensis
"Antarctosaurus" brasiliensis is based on two fragmentary leg bones and a partial vertebra from the Bauru Formation of Brazil, which were described in 1971 by Arid and Vizzotto. This species is also considered to be the noun dubium.
Individual evidence
- ^ Gregory S. Paul : The Princeton Field Guide To Dinosaurs. Princeton University Press, Princeton NJ et al. 2010, ISBN 978-0-691-13720-9 , p. 209, online .
- ↑ Ben Creisler: Dinosauria Translation and Pronunciation Guide. Archived from the original on November 6, 2011 ; accessed on August 27, 2014 .
- ↑ Louis L. Jacobs, Dale A. Winkler, William R. Downs, Elizabeth M. Gomani: New Material of an early cretaceous Titanosaurid Sauropod Dinosaur from Malawi. In: Palaeontology. Vol. 36, No. 3, 1993, ISSN 0031-0239 , pp. 523-534, digitized version (PDF; 1.05 MB) ( Memento from December 8, 2015 in the Internet Archive ).
- ↑ Jeffrey A. Wilson: An Overview of Titanosaur Evolution and Phylogeny. In: Fidel Torcida Fernández-Baldor, Pedro Huerta Hurtado (eds.): Actas de las III Jornadas Internacionales sobre Paleontología de Dinosaurios y Su Entorno. = Proceedings of the 3rd International Symposium about Paleontology of Dinosaurs and their Environment Paleontología de dinosaurios y su entorno. Salas de los Infantes (Burgos, España), 16 al 18 de septiembre de 2004. Colectivo arqueológico-paleontológico de Salas, Salas de los Infantes (Burgos, España) 2006, ISBN 84-8181-227-7 , pp. 169-190 .
- ↑ Kristina Curry Rogers: Titanosauria: A Phylogenetic Overview. In: Kristina Curry A. Rogers, Jeffrey A. Wilson (Eds.): The Sauropods. Evolution and Paleobiology. University of California Press, Berkeley CA et al. 2005, ISBN 0-520-24623-3 , pp. 50-103, doi : 10.1525 / california / 9780520246232.003.0003 .
- ↑ a b c d e Paul Upchurch , Paul M. Barrett , Peter Dodson : Sauropoda. In: David B. Weishampel , Peter Dodson, Halszka Osmólska (eds.): The Dinosauria . 2nd edition. University of California Press, Berkeley CA et al. 2004, ISBN 0-520-24209-2 , pp. 259-324.
- ↑ a b c Jeffrey A. Wilson: Redescription of the Mongolian Sauropod Nemegtosaurus mongoliensis Nowinski (Dinosauria: Saurischia) and comments on Late Cretaceous Sauropod diversity. In: Journal of Systematic Palaeontology. Vol. 3, No. 3, 2005, ISSN 1477-2019 , pp. 283-318, doi : 10.1017 / S1477201905001628 .
- ^ Friederich Baron Huene : Short review of the present knowledge of the Sauropoda. In: Memoirs of the Queensland Museum. Vol. 9, No. 1, 1927, ISSN 0079-8835 , pp. 121-126.
- ↑ Federico von Huene: Los saurisquios y ornitisquios del cretáceo argentino (= Anales del Museo de La Plata. Series 2, Vol. 3, ISSN 0327-7321 ). Universidad Nacionál de La Plata - Museo de La Plata, Buenos Aires 1929.
- ↑ Antarctosaurus . In: The Paleobiology Database. Retrieved August 27, 2014 .
- ^ A b Gerardo V. Mazzetta, Per Christiansen, Richard A. Fariña: Giants and Bizarres: Body Size of Some Southern South American Cretaceous Dinosaurs. In: Historical Biology. Vol. 16, No. 2/4, 2004, ISSN 0891-2963 , pp. 71-83, doi : 10.1080 / 08912960410001715132 , digital version (PDF; 574.66 kB) .
- ^ Friedrich Baron von Huene, Charles Alfred Matley: The Cretaceous Saurischia and Ornithischia of the Central Provinces of India (= Geological Survey of India. Palaeontologia Indica. NS Vol. 21, No. 1, ISSN 0970-0528 ). Manager of Publication, Delhi 1933.
- ↑ Jeffrey A. Wilson, Michael D. D'emic, Kristina A. Curry Rogers, Dhananjay M. Mohabey, Subashis Sen: Reassessment of the sauropod dinosaur Jainosaurus (= "Antarctosaurus") septentrionalis from the upper cretaceous of India. In: University of Michigan. Contributions from the Museum of Paleontology. Vol. 32, No. 2, 2009, ISSN 0097-3556 , pp. 17-40.
- ↑ Анатолий Н. Рябинин: Фауна позвоночных из верхнего мела Южного Казахстана. = The Upper Cretaceous vertebrate fauna of south Kazakhstan. I: Reptilia. Part 1: Ornithischia (= Труды Центрального Научно-исследовательского Геолого-разведочного Института (ЦНИГРИ). = Transactions of the Central Geological and Prospecting Institute. Fascicle 118 ZDB -ID 1063571-3 ). Гонти, Ленинград et al. 1939, digitized .
- ^ Fahad M. Arid, Luiz D. Vizotto: Antarctosaurus brasiliensis, around novo saurópode do Crétaceo superiordo sul do Brasil. In: Anais do XXV Congresso Brasileiro de Geologia. Sao Paulo, SP - Setembro 1971. Vol. 2, 1971, ZDB -ID 1061677-9 , pp. 297-305.
