Thursday 9 October 2014

A new Titanosaur from the Middle Cretaceous of southwest Tanzania.

Titanosaurs were the dominant group of Sauropod Dinosaurs throughout the Cretaceous, becoming more numerous and diverse as the period went on as the earlier Diplodocids became declined and became rarer. Despite the apparent global success of the group, only four species have previously been described from Africa, two each from Malawi and Egypt.

In a paper published in the Journal of Vertebrate Paleontology on 9 September 2014, Eric Gorscak of the Department of Biological Sciences and Ohio Center for Ecology and Evolutionary Studies at Ohio University, PatrickO'Connor and Nancy Stevens of the Ohio Center for Ecology and Evolutionary Studies and Department of Biomedical Sciences at the Ohio University HeritageCollege of Osteopathic Medicine and Eric Roberts of the School of Earth andEnvironmental Sciences at James Cook University describe a new species of Titanosaur from the Middle Cretaceous Galula Formation in the Rukwa Rift Basin of southwestern Tanzania. The Galula Formation is thought to represent a broad floodplain with a meandering river which was laid down between 100 and 110 million years ago.

The new Dinosaur is named Rukwatitan bisepultus, where ‘Rukwa’ refers both to the Rukwa Rift Basin and Lake Rukwa, which is close to the site where the specimen was found, and ‘titan’ refers to the titans of Greek mythology, strictly the children of Uranus but more generally anything large or brutish, while ‘bisepultus’ means ‘twice-burried’, a reference to the way in which the specimen was preserved; first buried within a channel of a river, then partially exposed by a new channel, then reburied. This is fairly typical within the Galula Formation, where most fossils are found as individual bones, disarticulated and scattered by the action of the river.

Quarry map (A) of the locality where the specimen was found and rose diagram (B) to indicate predominant paleocurrent orientations of elements in different facies; (C) photograph of in situ skeletal elements of Rukwatitan bisepultus in the quarry wall at the locality to illustrate the distinction between overbank and channel facies (see white hashed line); (D) middle caudal vertebra of Rukwatitanbisepultus in left lateral view illustrating matching contact areas of a single bone that was partially eroded (in the deep past), mobilised over a very short distance (approximately 1.5 m), and redeposited as part of a channel facies. Abbreviations: H, left humerus, proximal portion; H’, left humerus, distal portion; IL, leftilium; SC, left scapular blade; VR, vertebral rib. Scale bar in (D) equals 5 cm. Gorscak et al. (2014).

The new species is described from a partial skeleton comprising numerous partial and intact vertebrae, several ribs, part of the left scapula, parts of both coracoids, the left humerus and ilium, and parts of the right ulna and pubis.

Silhouette reconstruction of Rukwatitan bisepultus to illustrate those portions of the skeleton recovered. Scale bar equals 1 m. Gorscak et al. (2014).

See also…

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