Adocus

Abstract: The record of turtles in the Denver Basin spans four formations (Fox Hills, Laramie, Arapahoe, and Denver) that range from Late Cretaceous (Lancian) to early Paleocene (Puercan) in age. We recognize at least fifteen distinct, although fragmentary, species-level taxa, including Pleurosternidae ( Compsemys ), Baenidae ( Neurankylus, Plesiobaena, Stygiochelys , and Palatobaena ), Kinosternia ( Hoplochelys ), Adocidae ( Adocus ), Nanhsiungchelyidae ( Basilemys ), Trionychidae ( Axestemys, Aspideretoides, Helopanoplia , and another plastomenine), Macrobaenidae, and Chelydridae. Notable among these are the best-preserved skull of Compsemys , a new chelydrid genus, the most northerly confirmed record of Hoplochelys , and the most southerly records of Helopanoplia , Stygiochelys , and Macrobaenidae in the Rocky Mountain region. We also present evidence for synonymy of Paleotrionyx and Conchochelys with Axestemys , and the first cranial material assignable to Axestemys . The early Paleocene (Puercan) part of the Denver Formation yielded the most diverse assemblage, followed by the Cretaceous (Lancian) part of the Denver Formation and Laramie Formation. The Cretaceous samples are not demonstrably different from more northerly comparable faunas, but the more diverse Paleocene part of the Denver Formation exhibits a unique combination of taxa compared to contemporaneous faunas to the north and south.

Abstract: Cryptodires Xinjiangchelys tianshanensis , sp. nov. (Xinjiangchelyidae) from the middle Jurassic of Kirghizia, « Trionyx » kyrgyzensis sp. nov. (Trionychidae) from the early Cretaceous of Kyrgyzstan are diagnosed. Piece of carapace of another cryptodire Adocus sp. (Adocidae) from the late Cretaceous of Kazakhstan is described. Turtle X. tianshanensis is one of the oldest known indisputable cryptodires of Asia, « T. » kyrgyzensis is the oldest or one of three oldest species among described trionychids.

Abstract: The fossil turtles from the Upper Cretaceous Fruitland and Kirtland formations (late Campanian; Kirtlandian) have been known for more than 100 years. We re-assess and revise these Late Cretaceous testudine taxa from the San Juan Basin, New Mexico, USA, and discuss their biostratigraphic distribution. We recognize the following valid taxa as present: the bothremydid Chedighaii hutchisoni; the pleurosternid Compsemys sp.; the baenodds Denazinemys nodosa and Scabremys gen. nov., established for the distinct species S. ornata, previously included in Denazinemys; and Boremys grandis, though it is a rare taxon. The non-baenodd baenid Neurankylus baueri is recognized as a valid species. Two additional non-baenodd baenid taxa, Thescelus hemispherica and T. rapiens, are retained as distinct species and are not considered synonymous with T. insiliens. We also recognize a small indeterminate kinosternoid similar to that reported from the Campanian of Mexico. The two adocids Adocus bossi and A. kirtlandius are retained as distinct species. The nanhsiungchelyid Basilemys gaffneyi sp. nov. is established, whereas Basilemys nobilis is considered a nomen dubium because it lacks the diagnostic features that would allow referral to any known valid species. We recognize three trionychids: Aspideretoides austerus and A. robustus (new combination), and an unnamed plastominine. We synomize Aspideretoides fontanus and A. vorax with A. austerus. Aspideretoides ovatus is considered a subadult of A. robustus. The unnamed plastominine may represent a new genus and species. Turtles of the Fruitland-Kirtland formations resemble other late Campanian turtle assemblages from western North America, and are part of the characteristic vertebrate fauna of the Kirtlandian land-vertebrate age. The upper Fruitland and lower Kirtland formations (Hunter Wash local fauna) have greater turtle taxonomic diversity than the upper Kirtland Formation (Willow Wash local fauna). This apparent decrease in taxonomic diversity is interpreted as being real and reflects a shift in depositional (channel) environments to a more terrestrial one, a pattern which is seen in other North American Late Cretaceous settings.