New Cranial Material of Gilmoremys lancensis (Testudines, Trionychidae) from the Hell Creek Formation of Southeastern Montana, U.S.A.

  title={New Cranial Material of Gilmoremys lancensis (Testudines, Trionychidae) from the Hell Creek Formation of Southeastern Montana, U.S.A.},
  author={Walter G. Joyce and Tyler R. Lyson and Scott A. Williams},
  journal={Journal of Vertebrate Paleontology},
ABSTRACT 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… 
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  • Geography, Environmental Science
    Bulletin of the Peabody Museum of Natural History
  • 2017
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
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A new phylogenetic hypothesis informed by high resolution computed tomographic data of living and fossil taxa is presented, indicating three independent evolutionary transitions to marine life in non‐pleurodiran turtles (plus an additional two‐three in pleurodires).
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New Material of Gilmoremys lancensis nov. comb. (Testudines: Trionychidae) from the Hell Creek Formation and the Diagnosis of Plastomenid Turtles
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 plastomid turtles, in particular the contribution of the parietal to the orbit wall and the extensive secondary palate.
A New Soft-Shelled Trionychid Turtle of the Genus Khunnuchelys from the Upper Cretaceous Bostobe Formation of Kazakhstan
Previously unpublished trionychid turtle material from the Upper Cretaceous (Santonian—lower Campanian) Bostobe Formation from the Baybishe and Baykhozha localities in Kazakhstan is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
A New Species of Palatobaena (Testudines: Baenidae) and a Maximum Parsimony and Bayesian Phylogenetic Analysis of Baenidae
The baenid topology reveals a demonstrably homoplastic trend towards the reduction of the temporal emargination and unique thickening of the posterior portion of the parietals that corresponds with the K/T boundary and is hypothesized to have provided limited protection from increasingly effective mammalian predators.
Two New Plastomenine Softshell Turtles from the Paleocene of Montana and Wyoming
A phylogenetic analysis places the new species of plastomenine softshell turtles (Trionychidae) that are referred to Hutchemys gen. nov in a clade that is sister to Plastomenus aff.
T. ikoviensis is the easternmost representative of Trionyx sensu lato (sensu Lapparent de Broin 2001) and represents the first discovery of a trionychid skull in the Cenozoic deposits of the Ukraine in particular and the best discovery of this kind from the Censozoic of the former USSR in general.
The First Soft-Shelled Turtle from the Jehol Biota of China
High levels of homoplasy make the phylogenetic relationships of the new taxon difficult to assess, and the possibility therefore exists that Perochelys lamadongensis either represents a stem or a crown trionychid.
New Material and a Reassessment of Soft-Shelled Turtles (Trionychidae) from the Late Cretaceous of Middle Asia and Kazakhstan
Previously unpublished trionychid turtle material, consisting of numerous shell fragments, from two Late Cretaceous (Santonian—early Campanian) localities from Middle Asia and Kazakhstan are described, providing the first clear evidence for the relationship between Cret Jurassic Asian and North American trionYchids.
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Two new genera (Derrisemys and Plastomenoides) and three new species (D. sterea, P. lamberti, P. tetanetron) of plastomenine trionychids from Montana and Wyoming are described. They are unique within
Insights into the Taxonomy and Systematics of North American Eocene Soft-Shelled Turtles from a Well-Preserved Specimen
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A nearly complete fossil soft-shelled turtle from the Eocene Washakie Formation of Wyoming is described and identified as Oliveremys uintaensis, comb.