Two New Plastomenine Softshell Turtles from the Paleocene of Montana and Wyoming

@inproceedings{Joyce2009TwoNP,
  title={Two New Plastomenine Softshell Turtles from the Paleocene of Montana and Wyoming},
  author={Walter G. Joyce and Ariel Revan and Tyler R. Lyson and Igor G. Danilov},
  year={2009}
}
ABSTRACT The many fossil turtle remains collected by Princeton University throughout the 1950s and 1960s from Paleocene sediments in Montana and Wyoming include two new species of plastomenine softshell turtles (Trionychidae) that are referred to Hutchemys gen. nov., which corresponds to the previously used informal taxon “Plastomenine Type A.” Hutchemys is unique among trionychids in having a broadly rounded entoplastron that is underlain by a large rectangular callosity and fully immobilized… 
New Material of Gilmoremys lancensis nov. comb. (Testudines: Trionychidae) from the Hell Creek Formation and the Diagnosis of Plastomenid Turtles
TLDR
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.
The shell morphology of the latest Cretaceous (Maastrichtian) trionychid turtle Helopanoplia distincta
TLDR
Shell remains of eight fossils referable to Helopanoplia distincta from the Hell Creek Formation of Montana and North Dakota are described that document nearly all aspects of the shell morphology of this taxon and place it as sister to the clade formed by Plastomenus thomasii and Hutchemys spp.
Insights into the Taxonomy and Systematics of North American Eocene Soft-Shelled Turtles from a Well-Preserved Specimen
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  • Geography, Environmental Science
  • 2011
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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.
New Cranial Material of Gilmoremys lancensis (Testudines, Trionychidae) from the Hell Creek Formation of Southeastern Montana, U.S.A.
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 First Soft-Shelled Turtle from the Jehol Biota of China
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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.
“Macrobaenidae” (Testudines: Eucryptodira) from the Late Paleocene (Clarkforkian) of Montana and the Taxonomic Treatment of “Clemmys” backmani
ABSTRACT Two partial “macrobaenid” shells are described from a single Late Paleocene (Clarkforkian 1) quarry at Burns Mine near Washoe, Carbon County, Montana, USA, and are referred to “Clemmys”
Palaeoamyda messeliana nov. comb. (Testudines, Pan-Trionychidae) from the Eocene Messel Pit and Geiseltal localities, Germany, taxonomic and phylogenetic insights
TLDR
A revised diagnosis for the species is presented here, together with its inclusion in a phylogenetic analysis of Pan-Trionychidae that shows that this species is sister to the extant Amyda cartilaginea, one of the most abundant pan-trionyblade turtles from Asia, both members of the clade Chitrini.
Giant fossil soft-shelled turtles of North America
  • N. Vitek
  • Environmental Science, Biology
  • 2012
TLDR
Two new species are established and the taxon name ‘Axestemys’ is best defined phylogenetically as a stem-based clade rather than defined based on many of the characters traditionally ascribed to it, which are not consistently present throughout all species of Axstemys.
A New Plastomenid Trionychid Turtle, Plastomenus joycei, sp. nov., from the Earliest Paleocene (Danian) Denver Formation of South-Central Colorado, U.S.A.
ABSTRACT North American soft-shelled turtles, including trionychines and plastomenids, are incredibly abundant in latest Cretaceous through earliest Paleocene sediments. Here we describe a new
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