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[dinosaur] Tylosaurus saskatchewanensis (new species) + African araripemydid turtle Taquetochelys decorata

Ben Creisler

New papers:

Tylosaurus saskatchewanensis sp. nov.Â

Paulina JimÃnez-Huidobro, Michael W. Caldwell, Ilaria Paparella & Timon S. Bullard (2018)
A new species of tylosaurine mosasaur from the upper Campanian Bearpaw Formation of Saskatchewan, Canada.
Journal of Systematic Palaeontology (advance online publication)
doi:Â https://doi.org/10.1080/14772019.2018.1471744Â Â

Mosasaurs assigned to the genus Tylosaurus have been reported from the North Atlantic Circle Basin, including the Western Interior Seaway in North America and Europe, from the Turonian of Chihuahua, Mexico, to the early Maastrichtian of Belgium. The youngest record of Tylosaurus in North America is from the middle Campanian of the Pierre Shale, South Dakota. Data obtained by examination of an almost complete skull and associated postcranial elements of a large tylosaurine mosasaur from the upper Campanian of Saskatchewan supports the recognition of this specimen as a new species, Tylosaurus saskatchewanensis sp. nov. The specimen, collected from the Bearpaw Formation, southern Saskatchewan, Canada, presents unique features and combinations of features. It is recognized as a tylosaurine based on: edentulous rostrum; relatively long suprastapedial process of quadrate not reaching infrastapedial process; predental anterior extension of dentaries; and 12â13 maxillary and dentary teeth. Some of the characters that support recognition of the new species include: exclusion of prefrontal from dorsal rim of orbit by anterior process of postorbitofrontal; frontal extends anteriorly well into narial openings; well developed dorsal midline eminence of frontal; straight margins of parietal table; small infrastapedial process of quadrate located high on quadrate shaft almost touching suprastapedial process; thick tympanic ala of quadrate; 55 vertebrae anterior to chevron-bearing caudals; and rounded astragalus with big semicircular crural emargination. The new species represents the most northern occurrence of the genus and the subfamily and extends the stratigraphical distribution of the genus Tylosaurus in North America, occupying the northern Western Interior Seaway during the late Campanian.





AdÃn PÃrez-GarcÃa (2018)
Identification of the Lower Cretaceous pleurodiran turtle Taquetochelys decorata as the only African araripemydid species.
Taquetochelysdecorata, tortue pleurodire du CrÃtacà InfÃrieur: seule espÃce dâAraripemydidà d'Afrique.
ÂComptes Rendus Palevol (advance online publication)
doi: https://doi.org/10.1016/j.crpv.2018.04.004

Araripemydidae is a clade of freshwater pleurodiran turtles originally described in South America, where it is represented by the Brasilian AptianâAlbian Araripemys barretoi. Two potential members of this lineage were defined in an Aptian level of Africa, in Gadoufaoua (Niger): Taquetochelys decorata, described from several isolated plates, and Lagaremys tenerensis, known from an almost complete skeleton. The review of the Araripemydidae record, and the analysis of the intraspecific variability present in that and in other clades of Pleurodira, allow me to refute their attribution to two different forms. 'âL. tenerensis' is here recognized as a junior synonym of T. decorata. Therefore, the priority of T. decorata is demonstrated, as well as its attribution to Araripemydidae. The almost complete skeletal anatomy of the two currently recognized members of this AptianâAlbian clade (i.e. the African T. decorata and the South American A. barretoi) is well known, which is uncommon for the Cretaceous pleurodiran turtles.