New Specimens of a Titanosaur Sauropod from the Maastrichtian of Big Bend National Park, Texas

New specimens of a titanosaur sauropod from Maastrichtian strata in Big Bend National Park, Texas, include well-preserved dorsal vertebrae in association with pelvic elements. Anterior dorsal vertebrae are characterized by postspinal and centroprezygapophyseal laminae, with spinodiapophyseal laminae...

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Bibliographic Details
Published in:Journal of vertebrate paleontology 2014-07, Vol.34 (4), p.883-899
Main Authors: Fronimos, John A, Lehman, Thomas M
Format: Article
Language:English
Subjects:
Dinosaurs
Humerus
Peduncle
Pelvic bones
Sacral spine
Sacrum
Spine
Taxa
Vertebrae
Vertebrate paleontology
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Description
Summary:New specimens of a titanosaur sauropod from Maastrichtian strata in Big Bend National Park, Texas, include well-preserved dorsal vertebrae in association with pelvic elements. Anterior dorsal vertebrae are characterized by postspinal and centroprezygapophyseal laminae, with spinodiapophyseal laminae convergent on the anterior base of the neural spine. Posterior dorsal vertebrae are characterized by postzygodiapophyseal laminae and divided spinodiapophyseal laminae, with spinoprezygapophyseal laminae contributing to the prespinal lamina. The ilium and pubis differ from specimens previously collected, indicating a greater morphological disparity among titanosaurs in the Maastrichtian of West Texas than previously recognized. This disparity may be attributable to intraspecific variation or to the presence of multiple taxa. The new material is compatible with the only presently known North American titanosaur, Alamosaurus sanjuanensis, but is not formally referred due to lack of overlap with the hypodigm of that species. Comparison with other derived titanosaurs finds the closest affinities to Trigonosaurus pricei, Uberabatitan riberoi, and Baurutitan britoi of the Upper Cretaceous Brazilian Bauru Group, consistent with a South American immigration event at the end of the North American sauropod hiatus.
ISSN:0272-4634
1937-2809
DOI:10.1080/02724634.2014.840308