Amargatitanis
| Amargatitanis | ||||||||||||
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| Temporal occurrence | ||||||||||||
| Lower Cretaceous ( Barremium ) | ||||||||||||
| 130.7 to 126.3 million years | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Amargatitanis | ||||||||||||
| Apesteguía , 2007 | ||||||||||||
| Art | ||||||||||||
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Amargatitanis is a genus of sauropod dinosaurs from the Titanosauria group thatlived in South Americaduring the Lower Cretaceous . The fragmentary remains come from the Barremium of the La Amarga Formation in the Argentine province of Neuquén . Amargatitanis was a derived (advanced) representative of the Titanosauria, as they are mainly known from the Upper Cretaceous. This genus shows that such derived titanosaurs already existed in the Lower Cretaceous. The only species in this genus is Amargatitanis macni .
features
Amargatitanis is differentiated from other genera on the basis of features of the shoulder region and the hind leg. For example, the shoulder blade was flat and wide with the edges of the central shaft straight. The fourth trochanter of the femur (a bone process serving as a muscle attachment point) was located halfway up the bone. While the head of the thigh bone is very pronounced, the distal (lower) end is only weakly pronounced.
Find, research history and naming
The only previously known fossils were found in 1983 by an excavation team led by José Bonaparte . The site is located east of the city of Las Coloradas in the Argentine province of Neuquén . The site is probably attributable to the La Amarga Formation , which was deposited in the Barremium ; although find notes by José Bonaparte indicate that the site of the discovery is to be assigned to the much older Pichi-Picún formation , which was already deposited in the Upper Jurassic in the Kimmeridgian . Other known sauropods of the La Amarga Formation include basal (original) Titanosauria and Diplodocoidea from the groups Rebbachisauroidea and Dicraeosauridae as well as a basal representative of the Diplodocoidea.
The only find so far ( holotype , specimen numbers MACN PV N51, 53, 34) includes six caudal vertebrae, a shoulder blade, a femur and an ankle bone (astragalus). The first description of the new genus and species Amargatitanis macni was published in 2007 by Sebastián Apesteguía . The name points on the one hand to the place of discovery and on the other hand to the titans of Greek mythology , as an indication of the genus belonging to the Titanosauria. The second part of the species name, macni , is named after the Museo Argentino de Ciencias Naturales (MACN), which made significant contributions to the study of fossil vertebrates during the 19th and 20th centuries.
Individual evidence
- ↑ a b c d e Sebastián Apesteguía: The sauropod diversity of the La Amarga Formation (Barremian), Neuquén (Argentina). In: Gondwana Research . Vol. 12, No. 4, 2007, ISSN 1342-937X , pp. 533-546, doi : 10.1016 / j.gr.2007.04.007 .