Saturday, 29 October 2016

Mendozachelys wichmanni: A new species of Turtle from the Late Cretaceous of Argentina.

During the Late Cretaceous rising sea levels caused the Atlantic Ocean to cover much of what is now Patagonia, laying down a succession of marine sediments that are collectively known as the Malargüe Group. The lowermost deposits of this group are the sediments of the Loncoche Formation, which are interpreted as having been laid down in coastal lagoons, estuaries, tidal flats and deltaic to shallow marine environments along a narrow, elongate embayment. These sediments have produced a range of marine and terrestrial Vertebrate fossils, including Fish, Turtles, Tortoises, Theropods, Titanosaurs and Plesiosaurs. 

In a paper published in the journal Cretaceous Research on 21 September 2016, Marcelo de la Fuente, Ignacio Maniel, and Juan Marcos Jannello of the Grupo Vinculado al Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales at the Museo de Historia Natural deSan Rafael and The National Scientific and Technical Research Councilof Argentina, Juliana Sterli, also of The National Scientific and Technical Research Council of Argentina, and of the MuseoPaleontológico EgidioFeruglio, Bernardo Gonzalez Riga, again of The National Scientific and Technical Research Council of Argentina, and also of the Laboratorio de Dinosaurios at the Universidad Nacional de Cuyo, and Fernando Novas of the Laboratorio de Anatomía Comparada y Evolución de los Vertebrados at the Museo Argentino de Ciencias Naturales“Bernardino Rivadavia”, and also of The National Scientific and Technical Research Council of Argentina describe a new species of Turtle from the Ranquil-Có exposure of the Loncoche Formation in Southern Mendoza Province, Argentina.

The new species named Mendozachelys wichmanni, where 'Mendozachelys' comes from 'Mendoza' the province where it was discovered, plus 'chelys', which is Greek for Turtle. It is described from a single specimen excavated in 1990 by a team lead by palaeontologist José Bonaparte, and given a preliminary description in a paper by the same authors presented at the 5th Turtle Evolution Symposium in Rio de Janeiro in 2015 and published in the journal PeerJ. The specimen is largely complete, if somewhat flattened, and was articulated when discovered, although it was disassembled during preparation. It is calculated to have had a shell length of about 190 mm when alive, and a histological examination of the bones of the shell suggests an aquatic or semi-aquatic lifestyle.

Mendozachelys wichmanni gen. et sp. nov. Loncoche Formation (Upper Cretaceous). Carapace dorsal view: (A) Photograph; (B) Drawing. De la Fuente et al. (2016).

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