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[dinosaur] Pliosaurus almanzaensis, new plesiosur species from Upper Jurassic of Argentina

Ben Creisler

A new paper:

Josà P. OâGorman, Zulma Gasparini & Luis A. Spalletti (2018)
A new Pliosaurus species (Sauropterygia, Plesiosauria) from the Upper Jurassic of Patagonia: new insights on the Tithonian morphological disparity of mandibular symphyseal morphology
Journal of Paleontology (advance online publication)

Most species of the genus Pliosaurus Owen, 1842 come from the Northern Hemisphere, however, a growing number of new specimens are now available from the Southern Hemisphere. Here, a new species of Pliosaurus is described, the second for the genus from the Southern Hemisphere, collected from the upper Tithonian (Jurassic) levels of the Vaca Muerta Formation, NeuquÃn Province, Patagonia. Pliosaurus almanzaensis new species is characterized by two autapomophies: the angular participating in the mandibular symphysis and the occipital condyle without a notochordal pit or several, irregularly arranged grooves. Additionally, P. almanzaensis n. sp. can be differentiated from other Pliosaurus species by the following characters: trihedral teeth, nine or more symphyseal alveoli, 15â17 post-symphyseal alveoli, and the parasphenoid without a ventral keel. Pliosaurus almanzaensis n. sp. shows that Pliosaurus species with nine or more symphyseal alveoli persisted until the late Tithonian, contrary to previous assumptions that only species with six symphyseal alveoli were present.

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