Browsing by Subject "testudines"
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Item Soft-Shelled Turtles (Trionychidae) from the Bissekty formation (Late Cretaceous: Late Turonian) of Uzbekistan: Shell-Based Taxa(2013-04) Danilov, Igor G.; Vitek, Natasha S.; Vitek, Natasha S.In this paper we describe previously unpublished trionychid turtle material, consisting of numerous shell fragments, from the Late Cretaceous (late Turonian) Bissekty Formation of the Dzharakuduk locality in Uzbekistan. This material is assigned to two shell-based taxa: Aspideretoides cf. riabinini and "Trionyx" cf. kansaiensis. The material which cannot be confidently attributed to these two taxa is identified as Trionychidae indet. In addition to these shell-based trionychid taxa, the Dzharakuduk turtle assemblage includes two skull-based taxa of trionychids (Khunnuchelys kizylkumensis and Trionychini indet.). The trionychids from the Bissekty Formation are most similar to trionychids from the younger (Santonian - early Campanian) Bostobe Formation of Kazakhstan, represented by three shell-based taxa (Aspideretoides riabinini, Paleotrionyx riabinini and "Trionyx" kansaiensis), and one skull-based taxon (Khunnuchelys sp.). We provide an improved understanding of the subtle similarities and differences between four closely related Cretaceous turtle assemblages of Middle Asia and Kazakhstan. (c) 2012 Elsevier Ltd. All rights reserved.Item Soft-Shelled Turtles (Trionychidae) from the Bissekty formation (Upper Cretaceous: Turonian) of Uzbekistan: Skull-Based Taxa and Probable Skull-Shell Associations(2013-06) Vitek, Natasha S.; Danilov, Igor G.; Vitek, Natasha S.In this paper we describe previously unpublished trionychid turtle material, consisting of skull fragments, from the Late Cretaceous (late Turonian) Bissekty Formation of the Dzharakuduk locality in Uzbekistan. This material is assigned to two taxa: the skull-based Khunnuchelys kizylkumensis Brinkman et al. (1993, Can. J. Earth Sci. 30, 2214-2223) and Trionychini indet. Two specimens which cannot be confidently attributed to these two taxa are considered Trionychidae indet. In addition to these trionychid taxa known from skulls, the Dzharakuduk turtle assemblage includes at least two shell-based taxa, Aspideretoides cf. A. riabinini and "Trionyx" cf. "T." kansaiensis. For this and other Late Cretaceous localities of Middle Asia and Kazakhstan, we suggest the probable skull-shell associations of Khunnuchelys spp. with "Trionyx" kansaiensis-like forms and Trionychini indet. with Aspideretoides-like forms. (C) 2013 Elsevier Ltd. All rights reserved.Item Soft-Shelled Turtles (Trionychidae) from the Cenomanian of Uzbekistan(2014-05) Vitek, Natasha S.; Danilov, Igor G.; Vitek, Natasha S.Localities from the Cenomanian of Uzbekistan are the oldest in Middle Asia and Kazakhstan to preserve two broadly sympatric species of trionychid turtle. Material described here comes from multiple Cenomanian formations from the Itemir locality, and from multiple localities in the Cenomanian Khodzhakul Formation. The first taxon from the locality, "Trionyx" cf. kyrgyzensis, has multiple morphological similarities with the older, Early Cretaceous "Trionyx" kyrgyzensis. In contrast, the second taxon, "Trionyx" dissolutus, has multiple similarities with "Trionyx" kansaiensis, one of two species of trionychid found in younger Late Cretaceous localities. "Trionyx" dissolutus bears some superficial resemblance to other trionychid taxa within the clade Plastomenidae because of its highly ossified plastron with a hyoplastral lappet and an epiplastral notch. However, Plastomenidae is diagnosed primarily through characters that are absent or cannot be observed in the available material of "T." dissolutus, and other shared features are plesiomorphic. In addition, "T" dissolutus shares other synapomorphies with Trionychinae. A heavily ossified plastron may be more homoplastric within Trionychidae than has been previously recognized. Finally, we provide an improved understanding of the subtle similarities and differences between several closely related Cretaceous turtle assemblages of Middle Asia and Kazakhstan. (C) 2014 Elsevier Ltd. All rights reserved.