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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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A new soft-shelled trionychid turtle of the genus Khunnuchelys from the Upper Cretaceous Bostobe Formation of Kazakhstan
2016Co-Authors: Natasha S. Vitek, Igor G. Danilov, Alexander O. Averianov, Zoological InstiAbstract:Previously unpublished trionychid turtle material from the Upper Cretaceous (Santonian–lower Campanian) Bostobe Formation from the Baybishe and Baykhozha localities in Kazakhstan is described. The material represents a new species of Khunnuchelys, a large, skull-based clade of Cretaceous Asian trionychids. Concordant with other partial skulls and fragmentary specimens described previously, Khunnuchelys lophorhothon sp. nov. has the unusual features of a beak-like maxilla and a vaulted, expanded triturating surface. In addition, the specimens reveal novel features including a constricted skull roof. Although estimates of the length of the carapace differ depending on estimation method, the skull belonged to a turtle of comparable size to the shell-based species “Trionyx ” kansaiensis from the same formation. It is likely that K. lophorhothon and “T. ” kansaiensis are synonymous, but this can be proved only by a find of associated skull and shell material
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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.
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 new soft-shelled trionychid turtle of the genus Khunnuchelys from the Upper Cretaceous Bostobe Formation of Kazakhstan
2016Co-Authors: Natasha S. Vitek, Igor G. Danilov, Alexander O. Averianov, Zoological InstiAbstract:Previously unpublished trionychid turtle material from the Upper Cretaceous (Santonian–lower Campanian) Bostobe Formation from the Baybishe and Baykhozha localities in Kazakhstan is described. The material represents a new species of Khunnuchelys, a large, skull-based clade of Cretaceous Asian trionychids. Concordant with other partial skulls and fragmentary specimens described previously, Khunnuchelys lophorhothon sp. nov. has the unusual features of a beak-like maxilla and a vaulted, expanded triturating surface. In addition, the specimens reveal novel features including a constricted skull roof. Although estimates of the length of the carapace differ depending on estimation method, the skull belonged to a turtle of comparable size to the shell-based species “Trionyx ” kansaiensis from the same formation. It is likely that K. lophorhothon and “T. ” kansaiensis are synonymous, but this can be proved only by a find of associated skull and shell material
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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.
Raymond P Henry - One of the best experts on this subject based on the ideXlab platform.
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the effect of aquatic o levels on diving and ventilatory behavior in soft shelled Trionyx spiniferus stinkpot sternotherus odoratus and mud turtles kinosternon subrubrum
Physiological and Biochemical Zoology, 1992Co-Authors: Paul A Stone, James L Dobie, Raymond P HenryAbstract:Diving and ventilatory behavior were observed in three species of bimodally breathing turtles: Trionyx spiniferus, Sternotherus odoratus, and Kinosternon subrubrum. These turtles have high, intermediate, and low reliances on aquatic gas exchange, respectively. Turtles with access to normoxic air were filmed in normoxic, hypoxic, and hyperoxic water. Ninety percent of all dives were shorter than 20 min. Despite differences in the partitioning of respiratory gas exchange, dive duration in normoxia did not differ among species. Dive duration was directly proportional to aquatic PO₂ in soft-shells and independent of aquatic PO₂ in mud turtles. Stinkpots had consistently but not significantly shorter dives in normoxia. Aquatic PO₂ had no effect on the ventilation patterns of soft-shells. Regardless of PO₂, soft-shells typically engaged in one breathing bout, during which one breath was taken, per emersion period. Stinkpots and mud turtles underwent more bouts ofbreathingper emersion period and took more breath...
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cutaneous surface area and bimodal respiration in soft shelled Trionyx spiniferus stinkpot sternotherus odoratus and mud turtles kinosternon subrubrum
Physiological and Biochemical Zoology, 1992Co-Authors: Paul A Stone, James L Dobie, Raymond P HenryAbstract:Total mass-specific cutaneous surface area was determined for three species of freshwater turtles: Trionyx spiniferus, Sternotherus odoratus, and Kinosternon subrubrum. Similarly sized individuals of the three species exhibited high, intermediate, and low values of cutaneous surface area, respectively. Respiratory gas exchange in both air and water was measured in unrestrained individuals of each species. Because the T. spiniferus used in these experiments were on the average over an order of magnitude heavier than the S. odoratus, these two species had similar mass-specific cutaneous surface areas, whereas both had considerably higher values than K. subrubrum. All species were bimodal breathers, exchanging gases with both air and water. The percent aquatic $\dot{V}O_{2}$ and $\dot{V}CO_{2}$ were highest in soft-shells (38% and 85%, respectively), intermediate in stinkpots (26% and 56%), and lowest in mud turtles (14% and 46%). The inverse pattern was observed for aerial gas exchange. Regression analysis ...
Paul A Stone - One of the best experts on this subject based on the ideXlab platform.
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the effect of aquatic o levels on diving and ventilatory behavior in soft shelled Trionyx spiniferus stinkpot sternotherus odoratus and mud turtles kinosternon subrubrum
Physiological and Biochemical Zoology, 1992Co-Authors: Paul A Stone, James L Dobie, Raymond P HenryAbstract:Diving and ventilatory behavior were observed in three species of bimodally breathing turtles: Trionyx spiniferus, Sternotherus odoratus, and Kinosternon subrubrum. These turtles have high, intermediate, and low reliances on aquatic gas exchange, respectively. Turtles with access to normoxic air were filmed in normoxic, hypoxic, and hyperoxic water. Ninety percent of all dives were shorter than 20 min. Despite differences in the partitioning of respiratory gas exchange, dive duration in normoxia did not differ among species. Dive duration was directly proportional to aquatic PO₂ in soft-shells and independent of aquatic PO₂ in mud turtles. Stinkpots had consistently but not significantly shorter dives in normoxia. Aquatic PO₂ had no effect on the ventilation patterns of soft-shells. Regardless of PO₂, soft-shells typically engaged in one breathing bout, during which one breath was taken, per emersion period. Stinkpots and mud turtles underwent more bouts ofbreathingper emersion period and took more breath...
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cutaneous surface area and bimodal respiration in soft shelled Trionyx spiniferus stinkpot sternotherus odoratus and mud turtles kinosternon subrubrum
Physiological and Biochemical Zoology, 1992Co-Authors: Paul A Stone, James L Dobie, Raymond P HenryAbstract:Total mass-specific cutaneous surface area was determined for three species of freshwater turtles: Trionyx spiniferus, Sternotherus odoratus, and Kinosternon subrubrum. Similarly sized individuals of the three species exhibited high, intermediate, and low values of cutaneous surface area, respectively. Respiratory gas exchange in both air and water was measured in unrestrained individuals of each species. Because the T. spiniferus used in these experiments were on the average over an order of magnitude heavier than the S. odoratus, these two species had similar mass-specific cutaneous surface areas, whereas both had considerably higher values than K. subrubrum. All species were bimodal breathers, exchanging gases with both air and water. The percent aquatic $\dot{V}O_{2}$ and $\dot{V}CO_{2}$ were highest in soft-shells (38% and 85%, respectively), intermediate in stinkpots (26% and 56%), and lowest in mud turtles (14% and 46%). The inverse pattern was observed for aerial gas exchange. Regression analysis ...
James L Dobie - One of the best experts on this subject based on the ideXlab platform.
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the effect of aquatic o levels on diving and ventilatory behavior in soft shelled Trionyx spiniferus stinkpot sternotherus odoratus and mud turtles kinosternon subrubrum
Physiological and Biochemical Zoology, 1992Co-Authors: Paul A Stone, James L Dobie, Raymond P HenryAbstract:Diving and ventilatory behavior were observed in three species of bimodally breathing turtles: Trionyx spiniferus, Sternotherus odoratus, and Kinosternon subrubrum. These turtles have high, intermediate, and low reliances on aquatic gas exchange, respectively. Turtles with access to normoxic air were filmed in normoxic, hypoxic, and hyperoxic water. Ninety percent of all dives were shorter than 20 min. Despite differences in the partitioning of respiratory gas exchange, dive duration in normoxia did not differ among species. Dive duration was directly proportional to aquatic PO₂ in soft-shells and independent of aquatic PO₂ in mud turtles. Stinkpots had consistently but not significantly shorter dives in normoxia. Aquatic PO₂ had no effect on the ventilation patterns of soft-shells. Regardless of PO₂, soft-shells typically engaged in one breathing bout, during which one breath was taken, per emersion period. Stinkpots and mud turtles underwent more bouts ofbreathingper emersion period and took more breath...
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cutaneous surface area and bimodal respiration in soft shelled Trionyx spiniferus stinkpot sternotherus odoratus and mud turtles kinosternon subrubrum
Physiological and Biochemical Zoology, 1992Co-Authors: Paul A Stone, James L Dobie, Raymond P HenryAbstract:Total mass-specific cutaneous surface area was determined for three species of freshwater turtles: Trionyx spiniferus, Sternotherus odoratus, and Kinosternon subrubrum. Similarly sized individuals of the three species exhibited high, intermediate, and low values of cutaneous surface area, respectively. Respiratory gas exchange in both air and water was measured in unrestrained individuals of each species. Because the T. spiniferus used in these experiments were on the average over an order of magnitude heavier than the S. odoratus, these two species had similar mass-specific cutaneous surface areas, whereas both had considerably higher values than K. subrubrum. All species were bimodal breathers, exchanging gases with both air and water. The percent aquatic $\dot{V}O_{2}$ and $\dot{V}CO_{2}$ were highest in soft-shells (38% and 85%, respectively), intermediate in stinkpots (26% and 56%), and lowest in mud turtles (14% and 46%). The inverse pattern was observed for aerial gas exchange. Regression analysis ...
