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Natasha S. Vitek - One of the best experts on this subject based on the ideXlab platform.
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redescription of the skull of trionyx kyrgyzensis and improved phylogenetic taxon sampling of cretaceous and palaeogene soft shelled turtles Trionychidae of asia including the oldest crown trionychids
Journal of Systematic Palaeontology, 2018Co-Authors: Natasha S. Vitek, Igor G. Danilov, Yasuhisa Nakajima, Ren HirayamaAbstract:Although fossils of Trionychidae are found as far back as the Early Cretaceous, their evolutionary history, including the origin of the crown clade, is poorly understood. Here, we use a microCT scan of the skull of ‘Trionyx’ kyrgyzensis from the late Early Cretaceous (Albian) of Kyrgyzstan as the basis for a thorough redescription of the cranial morphology of this species. New information includes the pattern of cranial circulation, which is comparable to all extant trionychids. A unique combination of cranial and postcranial characters of ‘Trionyx’ kyrgyzensis allows us to establish for it a new genus Petrochelys gen. nov. The data regarding Petrochelys kyrgyzensis are incorporated into a phylogenetic analysis. When Petrochelys kyrgyzensis is analysed without including additional, extinct taxa, it is placed in a highly derived position within the extant Nilssonia. However, the addition of five Cretaceous–Palaeogene taxa breaks up hypothesized long branches and results in more basal positions for Petroche...
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Redescription of the skull of ‘Trionyx’ kyrgyzensis and improved phylogenetic taxon sampling of Cretaceous and Palaeogene soft-shelled turtles (Trionychidae) of Asia, including the oldest crown trionychids
2017Co-Authors: Natasha S. Vitek, Igor G. Danilov, Yasuhisa Nakajima, Ren HirayamaAbstract:Although fossils of Trionychidae are found as far back as the Early Cretaceous, their evolutionary history, including the origin of the crown clade, is poorly understood. Here, we use a microCT scan of the skull of ‘Trionyx’ kyrgyzensis from the late Early Cretaceous (Albian) of Kyrgyzstan as the basis for a thorough redescription of the cranial morphology of this species. New information includes the pattern of cranial circulation, which is comparable to all extant trionychids. A unique combination of cranial and postcranial characters of ‘Trionyx’ kyrgyzensis allows us to establish for it a new genus Petrochelys gen. nov. The data regarding Petrochelys kyrgyzensis are incorporated into a phylogenetic analysis. When Petrochelys kyrgyzensis is analysed without including additional, extinct taxa, it is placed in a highly derived position within the extant Nilssonia. However, the addition of five Cretaceous–Palaeogene taxa breaks up hypothesized long branches and results in more basal positions for Petrochelys kyrgyzensis within recovered trees. All results support the hypothesis that Petrochelys kyrgyzensis is a crown trionychid and a member of Trionychinae. Our findings highlight the importance of including multiple extinct taxa in phylogenetic analyses prior to using any of those taxa as calibration points in divergence dating estimates. http://zoobank.org/urn:lsid:zoobank.org:pub:592B98BF-87DF-48A8-8AA2-543AAD21FC95
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a review of the fossil record of new world turtles of the clade pan Trionychidae
Bulletin of The Peabody Museum of Natural History, 2015Co-Authors: Natasha S. Vitek, Walter G JoyceAbstract:Abstract Turtles of the clade Pan-Trionychidae have a rich, but fragmentary fossil record in the New World, ranging from the Late Cretaceous to the Holocene. The clade immigrated to North America from Asia no later than the Cenomanian. From the Campanian to the middle Eocene, pan-trionychid diversity in the New World was higher than it is today. In the Neogene, pan-trionychids inhabited southern North America and coastal regions of northern South America. Their range subsequently contracted, and extant New World pan-trionychids are now limited to the eastern third of temperate North America. The ecology of extinct pan-trionychids was likely similar to that of extant pan-trionychids, although novel feeding ecology has been hypothesized for some morphologically derived taxa. Current phylogenies of crown Trionychidae recognize two major clades, Cyclanorbinae and Trionychinae, but the placement of most fossil taxa remains poorly resolved relative to these two primary clades. A taxonomic review of 101 named Ne...
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New Material of Ulutrionyx ninae from the Oligocene of Kazakhstan, with a Review of Oligocene Trionychids of Asia
Journal of Vertebrate Paleontology, 2015Co-Authors: Natasha S. Vitek, Igor G. DanilovAbstract:ABSTRACT Six species of soft-shelled turtles (Trionychidae) have been previously described from the Oligocene of Asia. Four of those species were described based on fossils from the Turgai Depression and Zaisan (D Zaysan) Depression of Kazakhstan. We reevaluate those four species in light of new material from the Oligocene Chelkarnurinskaya Svita of the Turgai Depression. The new material is described and identified as Ulutrionyx ninae. Based on our revision, only two valid species of trionychid are present in the Oligocene of Asia. The relatively low diversity of Oligocene trionychids in Asia is mirrored by low trionychid diversity in North America during the same time period.
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cretaceous soft shelled turtles Trionychidae of mongolia new diversity records and a revision
Journal of Systematic Palaeontology, 2014Co-Authors: Igor G. Danilov, Ren Hirayama, Vladimir B. Sukhanov, Shigeru Suzuki, Mahito Watabe, Natasha S. VitekAbstract:This paper is devoted to the description and revision of material of Cretaceous soft-shelled turtles (Trionychidae) of Mongolia. It includes the description of seven trionychid species, six of which are new, and two new genera: the cyclanorbine Nemegtemys conflata gen. et sp. nov. from the Nemegt Formation (Maastrichtian), and the trionychines Gobiapalone breviplastra gen. et sp. nov. from the Nemegt and Barungoyot (Campanian) formations, G. orlovi from the Baynshire Formation (Cenomanian–Santonian), ‘Trionyx’ baynshirensis sp. nov. from the Baynshire Formation, ‘T.’ gilbentuensis sp. nov. from the Nemegt Formation, ‘T.’ gobiensis sp. nov. from the Nemegt Formation, and ‘T.’ shiluutulensis sp. nov. from an unknown formation (Campanian). In addition, one shell from the ?Baynshire Formation of Khermin Tsav is assigned to Gobiapalone sp. The type material of Amyda menneri is considered to be Trionychidae indet. and Amyda menneri to be a nomen dubium. Finally, we revise other available materials of Cretaceous...
Igor G. Danilov - One of the best experts on this subject based on the ideXlab platform.
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redescription of the skull of trionyx kyrgyzensis and improved phylogenetic taxon sampling of cretaceous and palaeogene soft shelled turtles Trionychidae of asia including the oldest crown trionychids
Journal of Systematic Palaeontology, 2018Co-Authors: Natasha S. Vitek, Igor G. Danilov, Yasuhisa Nakajima, Ren HirayamaAbstract:Although fossils of Trionychidae are found as far back as the Early Cretaceous, their evolutionary history, including the origin of the crown clade, is poorly understood. Here, we use a microCT scan of the skull of ‘Trionyx’ kyrgyzensis from the late Early Cretaceous (Albian) of Kyrgyzstan as the basis for a thorough redescription of the cranial morphology of this species. New information includes the pattern of cranial circulation, which is comparable to all extant trionychids. A unique combination of cranial and postcranial characters of ‘Trionyx’ kyrgyzensis allows us to establish for it a new genus Petrochelys gen. nov. The data regarding Petrochelys kyrgyzensis are incorporated into a phylogenetic analysis. When Petrochelys kyrgyzensis is analysed without including additional, extinct taxa, it is placed in a highly derived position within the extant Nilssonia. However, the addition of five Cretaceous–Palaeogene taxa breaks up hypothesized long branches and results in more basal positions for Petroche...
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Redescription of the skull of ‘Trionyx’ kyrgyzensis and improved phylogenetic taxon sampling of Cretaceous and Palaeogene soft-shelled turtles (Trionychidae) of Asia, including the oldest crown trionychids
2017Co-Authors: Natasha S. Vitek, Igor G. Danilov, Yasuhisa Nakajima, Ren HirayamaAbstract:Although fossils of Trionychidae are found as far back as the Early Cretaceous, their evolutionary history, including the origin of the crown clade, is poorly understood. Here, we use a microCT scan of the skull of ‘Trionyx’ kyrgyzensis from the late Early Cretaceous (Albian) of Kyrgyzstan as the basis for a thorough redescription of the cranial morphology of this species. New information includes the pattern of cranial circulation, which is comparable to all extant trionychids. A unique combination of cranial and postcranial characters of ‘Trionyx’ kyrgyzensis allows us to establish for it a new genus Petrochelys gen. nov. The data regarding Petrochelys kyrgyzensis are incorporated into a phylogenetic analysis. When Petrochelys kyrgyzensis is analysed without including additional, extinct taxa, it is placed in a highly derived position within the extant Nilssonia. However, the addition of five Cretaceous–Palaeogene taxa breaks up hypothesized long branches and results in more basal positions for Petrochelys kyrgyzensis within recovered trees. All results support the hypothesis that Petrochelys kyrgyzensis is a crown trionychid and a member of Trionychinae. Our findings highlight the importance of including multiple extinct taxa in phylogenetic analyses prior to using any of those taxa as calibration points in divergence dating estimates. http://zoobank.org/urn:lsid:zoobank.org:pub:592B98BF-87DF-48A8-8AA2-543AAD21FC95
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New Material of Ulutrionyx ninae from the Oligocene of Kazakhstan, with a Review of Oligocene Trionychids of Asia
Journal of Vertebrate Paleontology, 2015Co-Authors: Natasha S. Vitek, Igor G. DanilovAbstract:ABSTRACT Six species of soft-shelled turtles (Trionychidae) have been previously described from the Oligocene of Asia. Four of those species were described based on fossils from the Turgai Depression and Zaisan (D Zaysan) Depression of Kazakhstan. We reevaluate those four species in light of new material from the Oligocene Chelkarnurinskaya Svita of the Turgai Depression. The new material is described and identified as Ulutrionyx ninae. Based on our revision, only two valid species of trionychid are present in the Oligocene of Asia. The relatively low diversity of Oligocene trionychids in Asia is mirrored by low trionychid diversity in North America during the same time period.
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cretaceous soft shelled turtles Trionychidae of mongolia new diversity records and a revision
Journal of Systematic Palaeontology, 2014Co-Authors: Igor G. Danilov, Ren Hirayama, Vladimir B. Sukhanov, Shigeru Suzuki, Mahito Watabe, Natasha S. VitekAbstract:This paper is devoted to the description and revision of material of Cretaceous soft-shelled turtles (Trionychidae) of Mongolia. It includes the description of seven trionychid species, six of which are new, and two new genera: the cyclanorbine Nemegtemys conflata gen. et sp. nov. from the Nemegt Formation (Maastrichtian), and the trionychines Gobiapalone breviplastra gen. et sp. nov. from the Nemegt and Barungoyot (Campanian) formations, G. orlovi from the Baynshire Formation (Cenomanian–Santonian), ‘Trionyx’ baynshirensis sp. nov. from the Baynshire Formation, ‘T.’ gilbentuensis sp. nov. from the Nemegt Formation, ‘T.’ gobiensis sp. nov. from the Nemegt Formation, and ‘T.’ shiluutulensis sp. nov. from an unknown formation (Campanian). In addition, one shell from the ?Baynshire Formation of Khermin Tsav is assigned to Gobiapalone sp. The type material of Amyda menneri is considered to be Trionychidae indet. and Amyda menneri to be a nomen dubium. Finally, we revise other available materials of Cretaceous...
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soft shelled turtles Trionychidae from the cenomanian of uzbekistan
Cretaceous Research, 2014Co-Authors: Natasha S. Vitek, Igor G. DanilovAbstract:Abstract 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.
Walter G Joyce - One of the best experts on this subject based on the ideXlab platform.
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a review of the fossil record of old world turtles of the clade pan Trionychidae
Bulletin of The Peabody Museum of Natural History, 2017Co-Authors: Georgios L Georgalis, Walter G JoyceAbstract:Abstract Turtles of the clade Pan-Trionychidae have a rich fossil record in the Old World, ranging from the Early Cretaceous (Hauterivian) to the Holocene. The clade most probably originated in Asia during the Early Cretaceous but spread from there to the Americas and Europe by the Late Cretaceous, to India and Australia by the Eocene, and to Afro-Arabia by the Neogene. The presence of a single pan-cyclanorbine in the Late Cretaceous (Maastrichtian) of Asia provides a minimum estimate for the age of the trionychid crown. As preserved, diversity was relatively high in Asia during the Late Cretaceous, but the subsequent, strong decline is likely a preservational bias, as extant faunas are relatively rich, especially throughout Asia. The range of trionychids contracted southward in Europe over the course of the Neogene, and the group is now locally extirpated. The group is now similarly absent from Arabia and Australia. A taxonomic review of the 180 named Old World taxa finds 42 nomina valida, 38 nomina inva...
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new cranial material of gilmoremys lancensis testudines Trionychidae from the hell creek formation of southeastern montana u s a
Journal of Vertebrate Paleontology, 2016Co-Authors: Walter G Joyce, Tyler R. Lyson, Scott A WilliamsAbstract:ABSTRACTPlastomenidae is a speciose clade of soft-shelled turtles (Trionychidae) known from Campanian to Eocene deposits throughout western North America. We here describe two large skulls from the Upper Cretaceous (Maastrichtian) Hell Creek Formation of Carter County, Montana, that document the adult morphology of the plastomenid Gilmoremys lancensis. Whereas juveniles of this species, as previously documented by five subadult skulls, have narrow skulls, a narrow processus trochlearis oticum, a deep and narrow median palatal groove, low accessory ridges, and a secondary palate fully formed by the maxilla, skeletally mature individuals have notably broad skulls, a broad processus trochlearis oticum, a shallow but broad median palatal groove, high accessory ridges, and a substantial contribution of the vomer to the secondary palate. An expanded phylogenetic analysis reveals that the Campanian Aspideretoides foveatus and the Paleocene Aspideretoides superstes, nov. comb., are situated within Plastomenidae a...
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New cranial material of Gilmoremys lancensis (Testudines, Trionychidae) from the Hell Creek Formation of southeastern Montana, U.S.A.
2016Co-Authors: Walter G Joyce, Tyler R. Lyson, Scott WilliamsAbstract:Plastomenidae is a speciose clade of soft-shelled turtles (Trionychidae) known from Campanian to Eocene deposits throughout western North America. We here describe two large skulls from the Upper Cretaceous (Maastrichtian) Hell Creek Formation of Carter County, Montana, that document the adult morphology of the plastomenid Gilmoremys lancensis. Whereas juveniles of this species, as previously documented by five subadult skulls, have narrow skulls, a narrow processus trochlearis oticum, a deep and narrow median palatal groove, low accessory ridges, and a secondary palate fully formed by the maxilla, skeletally mature individuals have notably broad skulls, a broad processus trochlearis oticum, a shallow but broad median palatal groove, high accessory ridges, and a substantial contribution of the vomer to the secondary palate. An expanded phylogenetic analysis reveals that the Campanian Aspideretoides foveatus and the Paleocene Aspideretoides superstes, nov. comb., are situated within Plastomenidae as sister to all previously identified plastomenid turtles, despite their general resemblance to trionychine soft-shelled turtles. The name Aspideretoides should therefore not be used as a taxonomic wastebasket for fossil trionychids with unclear phylogenetic relationships. SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP Citation for this article: Joyce, W. G., T. R. Lyson, and S. Williams. 2016. New cranial material of Gilmoremys lancensis (Testudines, Trionychidae) from the Hell Creek Formation of southeastern Montana, U.S.A. Journal of Vertebrate Paleontology, e1225748. DOI: 10.1080/02724634.2016.1225748.
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a review of the fossil record of new world turtles of the clade pan Trionychidae
Bulletin of The Peabody Museum of Natural History, 2015Co-Authors: Natasha S. Vitek, Walter G JoyceAbstract:Abstract Turtles of the clade Pan-Trionychidae have a rich, but fragmentary fossil record in the New World, ranging from the Late Cretaceous to the Holocene. The clade immigrated to North America from Asia no later than the Cenomanian. From the Campanian to the middle Eocene, pan-trionychid diversity in the New World was higher than it is today. In the Neogene, pan-trionychids inhabited southern North America and coastal regions of northern South America. Their range subsequently contracted, and extant New World pan-trionychids are now limited to the eastern third of temperate North America. The ecology of extinct pan-trionychids was likely similar to that of extant pan-trionychids, although novel feeding ecology has been hypothesized for some morphologically derived taxa. Current phylogenies of crown Trionychidae recognize two major clades, Cyclanorbinae and Trionychinae, but the placement of most fossil taxa remains poorly resolved relative to these two primary clades. A taxonomic review of 101 named Ne...
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new material of gilmoremys lancensis nov comb testudines Trionychidae from the hell creek formation and the diagnosis of plastomenid turtles
Journal of Paleontology, 2011Co-Authors: Walter G Joyce, Tyler R. LysonAbstract:Abstract Plastomenidae is a poorly diagnosed clade of extinct soft-shelled turtles (Trionychidae) known from the Campanian to Eocene of North America. Five skulls, a mandible, two carapaces, and numerous plastral remains from the Hell Creek Formation (Late Cretaceous, Maastrichtian) of North Dakota and Montana are referable to Gilmoremys lancensis nov. comb., a taxon previously known from a carapace and xiphiplastron only. Gilmoremys lancensis is diagnosed by a carapace that is covered by elongate sinusoidal grooves, distally expanded second costals, hyoplastral shoulders, an extensive secondary palate with accessory ridges, an extremely elongate mandible, a contribution of the parietal to the wall of the orbit, and a posterior ossified narial canal. A phylogenetic analysis of all well-known plastomenid turtles establishes Gilmoremys lancensis as the most basal known plastomenid and reveals that cranial characters are more reliable in diagnosing plastomenid turtles, in particular the contribution of the p...
Ren Hirayama - One of the best experts on this subject based on the ideXlab platform.
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redescription of the skull of trionyx kyrgyzensis and improved phylogenetic taxon sampling of cretaceous and palaeogene soft shelled turtles Trionychidae of asia including the oldest crown trionychids
Journal of Systematic Palaeontology, 2018Co-Authors: Natasha S. Vitek, Igor G. Danilov, Yasuhisa Nakajima, Ren HirayamaAbstract:Although fossils of Trionychidae are found as far back as the Early Cretaceous, their evolutionary history, including the origin of the crown clade, is poorly understood. Here, we use a microCT scan of the skull of ‘Trionyx’ kyrgyzensis from the late Early Cretaceous (Albian) of Kyrgyzstan as the basis for a thorough redescription of the cranial morphology of this species. New information includes the pattern of cranial circulation, which is comparable to all extant trionychids. A unique combination of cranial and postcranial characters of ‘Trionyx’ kyrgyzensis allows us to establish for it a new genus Petrochelys gen. nov. The data regarding Petrochelys kyrgyzensis are incorporated into a phylogenetic analysis. When Petrochelys kyrgyzensis is analysed without including additional, extinct taxa, it is placed in a highly derived position within the extant Nilssonia. However, the addition of five Cretaceous–Palaeogene taxa breaks up hypothesized long branches and results in more basal positions for Petroche...
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Redescription of the skull of ‘Trionyx’ kyrgyzensis and improved phylogenetic taxon sampling of Cretaceous and Palaeogene soft-shelled turtles (Trionychidae) of Asia, including the oldest crown trionychids
2017Co-Authors: Natasha S. Vitek, Igor G. Danilov, Yasuhisa Nakajima, Ren HirayamaAbstract:Although fossils of Trionychidae are found as far back as the Early Cretaceous, their evolutionary history, including the origin of the crown clade, is poorly understood. Here, we use a microCT scan of the skull of ‘Trionyx’ kyrgyzensis from the late Early Cretaceous (Albian) of Kyrgyzstan as the basis for a thorough redescription of the cranial morphology of this species. New information includes the pattern of cranial circulation, which is comparable to all extant trionychids. A unique combination of cranial and postcranial characters of ‘Trionyx’ kyrgyzensis allows us to establish for it a new genus Petrochelys gen. nov. The data regarding Petrochelys kyrgyzensis are incorporated into a phylogenetic analysis. When Petrochelys kyrgyzensis is analysed without including additional, extinct taxa, it is placed in a highly derived position within the extant Nilssonia. However, the addition of five Cretaceous–Palaeogene taxa breaks up hypothesized long branches and results in more basal positions for Petrochelys kyrgyzensis within recovered trees. All results support the hypothesis that Petrochelys kyrgyzensis is a crown trionychid and a member of Trionychinae. Our findings highlight the importance of including multiple extinct taxa in phylogenetic analyses prior to using any of those taxa as calibration points in divergence dating estimates. http://zoobank.org/urn:lsid:zoobank.org:pub:592B98BF-87DF-48A8-8AA2-543AAD21FC95
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FOSSIL TURTLES FROM THE NEOGENE STRATA IN THE SINDA BASIN, EASTERN ZAIRE
2016Co-Authors: Ren HirayamaAbstract:ABSTRACT Fossil turtles collected from the Sinda Beds of eastern Zaire contain three families. They are Erymnochelys Spa of family Pelomedusidae, gen. et Spa indet. of family Carettochelyidae, and gen. et Spa indet. of family Trionychidae. Among them is the first known occurrence from Africa of carettochelyid, the pig-nosed turtle, Erymnochelys, the big-headed side necked turtle, which once flourished in African during Tertiary, is restricted to Madagascar, today. All of these are presumed to have had aquatic habitat in rivers and lakes. RESUME Les fossiles des tortues collectees des couches de Sinda aI ' est du zaire contiennent trois familles. II y a Erymnochelys Spa de la famille Pelomedusidae (pseudemyde a grosse tete), une espece non identifiee de la famille de Carettochelydae (carettochelyde; tortue anez de porc), et famille Trionychidae (trionychide; tortues a carapace lisse). Parmi eux, carettochelyid est Ie premier connu de l ' afrique. Malgre que Erymnochelys a ete florissant en afrique durant Ie tertiaire, il est aujourd'hui limite au madagascar. Toutes ces tortues sont presumees avoir un habitat aquatique dans les rivieres et les lacs
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cretaceous soft shelled turtles Trionychidae of mongolia new diversity records and a revision
Journal of Systematic Palaeontology, 2014Co-Authors: Igor G. Danilov, Ren Hirayama, Vladimir B. Sukhanov, Shigeru Suzuki, Mahito Watabe, Natasha S. VitekAbstract:This paper is devoted to the description and revision of material of Cretaceous soft-shelled turtles (Trionychidae) of Mongolia. It includes the description of seven trionychid species, six of which are new, and two new genera: the cyclanorbine Nemegtemys conflata gen. et sp. nov. from the Nemegt Formation (Maastrichtian), and the trionychines Gobiapalone breviplastra gen. et sp. nov. from the Nemegt and Barungoyot (Campanian) formations, G. orlovi from the Baynshire Formation (Cenomanian–Santonian), ‘Trionyx’ baynshirensis sp. nov. from the Baynshire Formation, ‘T.’ gilbentuensis sp. nov. from the Nemegt Formation, ‘T.’ gobiensis sp. nov. from the Nemegt Formation, and ‘T.’ shiluutulensis sp. nov. from an unknown formation (Campanian). In addition, one shell from the ?Baynshire Formation of Khermin Tsav is assigned to Gobiapalone sp. The type material of Amyda menneri is considered to be Trionychidae indet. and Amyda menneri to be a nomen dubium. Finally, we revise other available materials of Cretaceous...
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Cretaceous soft-shelled turtles (Trionychidae) of Mongolia: new diversity, records and a revision
2014Co-Authors: Igor G. Danilov, Ren Hirayama, Vladimir B. Sukhanov, Shigeru Suzuki, Mahito Watabe, Natasha S. VitekAbstract:This paper is devoted to the description and revision of material of Cretaceous soft-shelled turtles (Trionychidae) of Mongolia. It includes the description of seven trionychid species, six of which are new, and two new genera: the cyclanorbine Nemegtemys conflata gen. et sp. nov. from the Nemegt Formation (Maastrichtian), and the trionychines Gobiapalone breviplastra gen. et sp. nov. from the Nemegt and Barungoyot (Campanian) formations, G. orlovi from the Baynshire Formation (Cenomanian–Santonian), ‘Trionyx’ baynshirensis sp. nov. from the Baynshire Formation, ‘T.’ gilbentuensis sp. nov. from the Nemegt Formation, ‘T.’ gobiensis sp. nov. from the Nemegt Formation, and ‘T.’ shiluutulensis sp. nov. from an unknown formation (Campanian). In addition, one shell from the ?Baynshire Formation of Khermin Tsav is assigned to Gobiapalone sp. The type material of Amyda menneri is considered to be Trionychidae indet. and Amyda menneri to be a nomen dubium. Finally, we revise other available materials of Cretaceous trionychids from 45 localities in Mongolia. Nemegtemys conflata, if correctly assigned, is the earliest known member of Cyclanorbinae. The two species of the new genus Gobiapalone are included in two phylogenetic analyses of Trionychidae. In both analyses Gobiapalone is monophyletic. In the first analysis, Gobiapalone is placed within Apalonina. In the second analysis, Gobiapalone is sister to Apalonina. Thus, the results of both analyses show that Apalonina, which is a rather advanced and well-supported trionychid clade, or its closest sister taxon (stem-Apalonina), were present in the Late Cretaceous of Asia. These results suggest that most other supra-generic clades of modern trionychids had been established in Asia by the Late Cretaceous. That suggestion is supported by the discovery of a cyclanorbine Nemegtemys conflata in the Late Cretaceous of Mongolia. Finally we summarize the latest data on temporal and geographical distributions of Cretaceous Trionychidae of Asia and North America.http://zoobank.org/urn:lsid:zoobank.org:pub:921DA1C5-C4B2-463D-A49D-608024C6036A
Yoichi Matsuda - One of the best experts on this subject based on the ideXlab platform.
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the zw micro sex chromosomes of the chinese soft shelled turtle pelodiscus sinensis Trionychidae testudines have the same origin as chicken chromosome 15
Cytogenetic and Genome Research, 2009Co-Authors: Taiki Kawagoshi, Yoichi Matsuda, Yoshinobu Uno, Kazumi Matsubara, Chizuko NishidaAbstract:The Chinese soft-shelled turtle (Pelodiscus sinensis, Trionychidae, Testudines) has ZZ/ZW-type micro-sex chromosomes where the 18S-28S ribosomal RNA genes (18S-28S rDNA) are located. The W chromosome is morphologically differentiated from the Z chromosome by partial deletion and amplification of 18S-28S rDNA and W-specific repetitive sequences. We recently found a functional gene (TOP3B) mapped on the P. sinensis Z chromosome, which is located on chicken (Gallus gallus, GGA) chromosome 15. Then we cloned turtle homologues of 4 other GGA15-linked genes (GIT2, NF2, SBNO1, SF3A1) and localized them to P. sinensis chromosomes. The 4 genes all mapped on the Z chromosome, and 2 of them (SBNO1, SF3A1) were also localized to the W chromosome. Our mapping data suggest that at least one large inversion occurred between GGA15 and the P. sinensis Z chromosome, and that there are homologous regions in the distal portions of both the short and long arms between the Z and W chromosomes. W chromosomal differentiation in P. sinensis probably proceeded by the deletion of the proximal chromosomal region followed by 18S-28S rDNA amplification, after a paracentric inversion occurred at the breakpoints between the distal region of 18S-28S rDNA and the proximal region of SBNO1 on the Z chromosome.
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Molecular and cytogenetic characterization of site-specific repetitive DNA sequences in the Chinese soft-shelled turtle (Pelodiscus sinensis, Trionychidae)
Chromosome Research, 2005Co-Authors: Kazuhiko Yamada, Chizuko Nishida-umehara, Yoichi MatsudaAbstract:A novel family of repetitive DNA sequences that are components of constitutive heterochromatin were cloned from Bgl I-digested genomic DNA of the Chinese soft-shelled turtle ( Pelodiscus sinensis , Trionychidae), and characterized by filter hybridization and chromosome in-situ hybridization. The Bgl I-family of repetitive sequences were classified into four types by their genome organization and chromosomal distribution as follows: the repeated sequences located on (1) two pairs of microchromosomes, (2) four pairs of microchromosomes,(3) about half the number of microchromosomes and (4) the interstitial region of the short arm of chromosome 2. The presence of microchromosome-specific repetitive sequences has also been reported in the Struthioniformes and Galliformes, suggesting that turtle chromosomes retain some similarity to the chromosome structure as well as the karyotypes of avian species
