Malarguesaurus
| Malarguesaurus | ||||||||||||
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| Temporal occurrence | ||||||||||||
| Upper Cretaceous (late Turonian to early Coniacian ) | ||||||||||||
| 93.9 to 86.3 million years | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Malarguesaurus | ||||||||||||
| Gonzáles Riga et al. , 2009 | ||||||||||||
| Art | ||||||||||||
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Malarguesaurus is a genus of sauropod dinosaur from the group of Titanosauriformes from the Upper Cretaceous South America. So far, only very fragmentary remains are known that come from the Portezuelo Formation in the Argentine province of Mendoza . The only known species is Malarguesaurus florenciae .
features
Malarguesaurus was a relatively large and robustly built sauropod - the type specimen is estimated to be around 20 meters long. It can be distinguished from other representatives of the Titanosauriformes by a combination of diagnostic features. The distal (rear) caudal vertebrae were procoel (concave on the front), while the proximal (front) and middle caudal vertebrae were procoel-ophistoplatysch (concave on the front and flat on the rear). In addition, the spinous processes of the proximal caudal vertebrae were oriented vertically, while the spinous processes of the distal caudal vertebrae have a concave dorsal edge.
Systematics
Malarguesaurus is one of the Titanosauriformes, a group within the Macronaria which includes the Brachiosauridae and the Titanosauria . This assignment is based on various jointly derived features ( synapomorphies ), such as the large, lateral hump in the upper area of the thighbone (femur) typical of titanosauriformes . According to a preliminary cladistic analysis of the first descriptors, Malarguesaurus belongs to the Somphospondyli within the Titanosauriformes - together with Euhelopus , Chubutisaurus , Ligabuesaurus , Phuwiangosaurus and all representatives of the Titanosauria. Malarguesaurus was probably closest related to Phuwiangosaurus - both genera together with Ligabuesaurus could have formed the sister group of the Titanosauria. However, other researchers classify Phuwiangosaurus as a basal (original) genus within the Titanosauria.
Finds, taphonomy and naming
So far, two finds are known. The type specimen (specimen number IANIGLA-PV 110) was discovered in 2005 by a research group led by the paleontologist Bernardo González Riga ; the site ( Quebrada Norte quarry ) is located in the Malargüe department of the province of Mendoza. The find includes proximal, middle and distal caudal vertebrae including chevron bones , dorsal ribs, a fragment of the upper arm bone (humerus) and a partial femur. Another copy (copy number IANIGLA PV-111) consists of two distal caudal vertebrae and a fragmentary fibula (fibula) - these references is derived from the about 600 meters from the quarry Quebrada Norte removed situated reference Cerro La Torre .
Both finds come from the Portezuelo Formation , which is dated to the late Turonian and the early Coniacian . The type specimen was recovered from solid mudstone (fine-grained sedimentary rock in the clay to silt range), which was deposited fluviatil in a floodplain . The bones were found scattered over an area of around 16 square meters, so they were no longer in the anatomical bond when they were embedded. Nevertheless, the shaft axes of the bones do not show a preferred orientation, which is why water as the cause of the dispersion can at best have played a subordinate role. Carnivores may have scattered the carcass, although the bones did not show any bite marks.
The name Malarguesaurus refers to the Malargüe department where the fossils were found. The second part of the species name, florenciae , honors Florencia Fernandez Favaron, who found the first fossils and helped with the paleontological field work.
Individual evidence
- ↑ a b c d e Bernardo J. González Riga, Elena Previtera, Cecilia A. Pirrone: Malarguesaurus florenciae gen. Et sp. nov., a new titanosauriform (Dinosauria, Sauropoda) from the Upper Cretaceous of Mendoza, Argentina. In: Cretaceous Research. Vol. 30, No. 1, 2009, ISSN 0195-6671 , pp. 135-148, doi : 10.1016 / j.cretres.2008.06.006 .