New Material of Gilmoremys lancensis nov. comb. (Testudines: Trionychidae) from the Hell Creek Formation and the Diagnosis of Plastomenid Turtles

  title={New Material of Gilmoremys lancensis nov. comb. (Testudines: Trionychidae) from the Hell Creek Formation and the Diagnosis of Plastomenid Turtles},
  author={Walter G. Joyce and Tyler R. Lyson},
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… 
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
A new species of trionychid turtle, Axestemys infernalis sp. nov., from the Late Cretaceous (Maastrichtian) Hell Creek and Lance formations of the Northern Great Plains, USA
The Late Cretaceous (Maastrichtian) Hell Creek and Lance formations in the states of North Dakota, South Dakota, Montana, and Wyoming, USA, have yielded rich remains of trionychid turtles, but the
A New Baenid Turtle, Saxochelys gilberti, gen. et sp. nov., from the Uppermost Cretaceous (Maastrichtian) Hell Creek Formation: Sexual Dimorphism and Spatial Niche Partitioning within the Most Speciose Group of Late Cretaceous Turtles
ABSTRACT The uppermost Cretaceous (Maastrichtian) Hell Creek Formation in North America has yielded a diverse assemblage of fossil turtles dominated by baenids. A population of over 30 individual
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Previously unpublished trionychid turtle material from the Upper Cretaceous (Santonian—lower Campanian) Bostobe Formation from the Baybishe and Baykhozha localities in Kazakhstan is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
The shell morphology of the latest Cretaceous (Maastrichtian) trionychid turtle Helopanoplia distincta
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.
A new baenid turtle from the early Paleocene (Torrejonian) of New Mexico and a species-level phylogenetic analysis of Baenidae
A nearly complete species-level analysis of baenids confirms the basal placement of Neurankylus outside of Baenodda and the split of Baensodda into two primary subclades, herein named Palatobaeninee and Eubaeninae.
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
Trionyx ikoviensis sp. nov., a new species of soft-shelled turtles (Trionychidae: Trionychinae), is established based on a partial but well preserved skull, isolated shell bones and cervical
Palaeoamyda messeliana nov. comb. (Testudines, Pan-Trionychidae) from the Eocene Messel Pit and Geiseltal localities, Germany, taxonomic and phylogenetic insights
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.
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.


A New Baenid Turtle from the Upper Cretaceous (Maastrichtian) Hell Creek Formation of North Dakota and a Preliminary Taxonomic Review of Cretaceous Baenidae
A fragmentary skull from the Hell Creek Formation of southwestern North Dakota represents a new taxon of baenid turtle named herein Gamerabaena sonsalla, which has several morphological features that are intermediate between Plesiobaena antiqua and the morphologically disparate Palatobaena spp.
Two New Plastomenine Softshell Turtles from the Paleocene of Montana and Wyoming
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
New soft-shelled turtles (Plastomeninae, Trionychidae, Testudines) from the Late Cretaceous and Paleocene of North America
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
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.
Cranial Anatomy and Phylogenetic Placement of the Enigmatic Turtle Compsemys victa Leidy, 1856
Taphonomic evidence reveals that basal paracryptodires, including C. victa, preferred slow moving or ponded water environments, and the riverine habitat preference of baenodds must therefore be derived.
A Revision of Plesiobaena (Testudines: Baenidae) and an Assessment of Baenid Ecology Across the K/T Boundary
The phylogenetic analysis clearly reveals that Plesiobaena in the traditional sense is a paraphyletic assemblage relative to the clade formed by Gamerabaena sonsalla and Palatobaena spp.
The first phylogenetic analysis of Trionychidae that includes a representative of the poorly studied taxon Plastomenidae reveals that plastomenids are stem cyclanorbines, thus reducing the apparent ghost range of total group Cy- clanorbinae to approximately 30 Ma.
Intraspecific variation in the cranial feeding mechanism of turtles of the genus Trionyx (Reptilia, Testudines, Trionychidae).
and time. Variation in the jaws of T. ferox is shown to be co-existent with variation in 1) other skull features which are presumed to be part of the cranial feeding mechanism, 2) the rhamphotheca or
Diversity of turtles across the cretaceous/tertiary boundary in Northeastern Montana
Abstract The abundant chelonian faunas of the Hell Creek and Tullock formations of McCone and Garfield counties, Montana, span the Cretaceous/Tertiary boundary and provide a basis for assessing
Multiple data sets, high homoplasy, and the phylogeny of softshell turtles (Testudines: Trionychidae).
A strong estimate of the phylogeny of softshell turtles is used as the basis for a novel rank-free classification, and strategies for analyzing highly homoplasious mtDNA data in deep phylogenetic problems where increased taxon sampling is not an option are examined.