Chubutemys, a new eucryptodiran turtle from the early Cretaceous of Argentina, and the relationships of the Meiolaniidae ; American Museum novitates, no. 3599

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dc.contributor.authorGaffney, Eugene S.en_US
dc.contributor.authorRich, Thomas H. V.en_US
dc.contributor.authorRich, Pat Vickers.en_US
dc.contributor.authorConstantine, Andrew Eric, 1965-en_US
dc.contributor.authorVacca, Raul.en_US
dc.contributor.authorKool, Lesley.en_US
dc.date.accessioned2007-12-18T17:50:50Z
dc.date.available2007-12-18T17:50:50Z
dc.date.issued2007en_US
dc.description35 p. : ill., maps ; 26 cm.en_US
dc.descriptionIncludes bibliographical references (p. 28-30).en_US
dc.description.abstractChubutemys copelloi is the oldest nonmarine cryptodire from South America represented by a skull. The skull and associated postcranial fragments are from the Aptian Cerro CostaŠno Member of the Cerro Barcino Formation of Chubut, Argentina. Chubutemys has a processus trochlearis oticum, showing that it is a cryptodire, and an enclosed canalis caroticus internus extending to the posterior margin of the pterygoid, showing that it is a eucryptodire. The skull of Chubutemys is similar to that of other primitive eucryptodires, particularly Dracochelys, but also to Hangaiemys, Judithemys, Sinemys, and Ordosemys. Chubutemys differs from all these, however, in possessing a solidly roofed skull, formed by long, wide parietals, rather than a posterior emargination. Chubutemys also differs from these taxa in having no cheek emargination. A phylogenetic analysis using PAUP* analyzed 104 parsimony-informative characters resolving into one most parsimonious cladogram of 224 steps, a consistency index of 0.55, and a retention index of 0.74. The phylogenetic analysis weakly joins Chubutemys and meiolaniids on the basis of the prefrontal-postorbital contact. Chubutemys also has a fully roofed skull and slitlike posterior opening of the foramen caroticum laterale (foramen posterius canalis caroticus laterale), features to be expected in a meiolaniid sister taxon. Chubutemys provides further evidence that meiolaniids are related to 'basal' eucryptodires ('sinemydids/macrobaenids'), that is, eucryptodires outside the living Cryptodira, the Polycryptodira. The basicranial morphology of meiolaniids, with an intrapterygoid slit, rather than being a unique feature of the group is instead a modified state of the primitive eucryptodire condition, as seen in such forms as Chubutemys, Dracochelys, Ordosemys, and Sinemys. The intrapterygoid slit of meiolaniids is homologous with the pterygoid flange associated with the foramen caroticum laterale (foramen posterius canalis caroticus laterale of Sukhanov) in non-Polycryptodiran eucryptodires like Ordosemys. Chubutemys shows that nonmarine eucryptodires were present in South America in the Cretaceous, as they were in North America, central Asia, and Australia.en_US
dc.format.extent6599823 bytes
dc.format.mimetypeapplication/pdf
dc.identifier.urihttp://hdl.handle.net/2246/5895
dc.languageengen_US
dc.language.isoen_US
dc.publisherNew York, NY : American Museum of Natural Historyen_US
dc.relation.ispartofseriesAmerican Museum novitates, no. 3599en_US
dc.subject.lccQL1 .A436 no.3599, 2007en_US
dc.subject.lcshChubutemys copelloi.en_US
dc.subject.lcshSkull -- Anatomy.en_US
dc.subject.lcshTurtles, Fossil -- Argentina -- Chubut.en_US
dc.subject.lcshReptiles, Fossil -- Argentina -- Chubut.en_US
dc.subject.lcshMeiolaniidae -- Phylogeny.en_US
dc.subject.lcshPaleontology -- Cretaceous -- Argentina -- Chubut.en_US
dc.subject.lcshPaleontology -- Argentina -- Chubut.en_US
dc.titleChubutemys, a new eucryptodiran turtle from the early Cretaceous of Argentina, and the relationships of the Meiolaniidae ; American Museum novitates, no. 3599en_US
dc.title.alternativeNew eucryptodiran turtleen_US
dc.typetexten_US

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