Topic
Compsemys
About: Compsemys is a research topic. Over the lifetime, 11 publications have been published within this topic receiving 335 citations.
Papers
1 Sep 2002
TL;DR: In this paper, the authors examined latest Cretaceous intraregional variability in this group, comparing these three areas to a large data set previously published from the Hell Creek Formation of Montana.
Abstract: Turtles are among the most widespread, abundant, and diverse fossil vertebrate groups in the latest Cretaceous. On the basis of new data from the Hell Creek Formation (North Dakota) and Lance and Ferris Formations (Wyoming) and previously published data from Montana, we examined latest Cretaceous intraregional variability in this group, comparing these three areas to a large data set previously published from the Hell Creek Formation of Montana. Using discrete locality occurrences as an index of relative abundance, significant differences were found. Trionychids are the only group that evinces no differences among the four study areas. Baenids and kinosternoids are more common than expected in North Dakota. The pleurosternid Compsemys, chelydrids, and Adocus are notably rare in the Ferris Formation, and the terrestrial turtle Basilemys is more abundant there than expected. The Lance Formation differs in the greater relative abundance of uncommon taxa, i.e., chelydrids, the macrobaenid "Clemmys" backmani, kinosternoids, and Basilemys. These differences are statistically independent of simple lithologic differences and thus appear to reflect underlying heterogeneity in the aquatic habitats of the latest Cretaceous that may not have obtained to the same degree in terrestrial habitats. The idea of heterogeneous aquatic habitats is consistent with depositional models indicating that the northern Great Plains area was dominated by dynamic fluvial systems that created an unstable landscape. Adaptation to fluctuating environments was probably a feature of latest Cretaceous aquatic vertebrate ecology and may be a factor in their greater relative success in surviving Cretaceous-Tertiary boundary events.
72 citations
TL;DR: Arundelemys dardeni, gen. et al. as discussed by the authors described an isolated, nearly complete skull from the Early Cretaceous Arundel Clay facies of Maryland, USA.
Abstract: A new paracryptodiran turtle, Arundelemys dardeni, gen. et sp. nov., is described on the basis of an isolated, nearly complete skull from the Early Cretaceous Arundel Clay facies of Maryland, USA. The basicranial region exhibits the paracryptodiran condition of a single foramen for the canalis caroticus internus located midway along the basisphenoid. As revealed by CT scans, the basicranial region of Arundelemys is unusual in that the right and left canales carotici interni merge just before reaching the sella turcica and the canalis caroticus lateralis is very small or absent. A phylogenetic analysis places Arundelemys dardeni as the basal-most member of the Paracryptodira. Within the Paracryptodira, Arundelemys dardeni is most similar to Compsemys victa in general proportions.
69 citations
1 Jan 2011
TL;DR: A series of typological taxon defini- tions that utilize shell sculpturing and retrieve consistent classes of fragments that originate from specific geological formations are developed to help clarify the palaeoecology of solemydid turtles.
Abstract: A beautifully preserved skull from the Barremian Wessex Formation of the Isle of Wight, England, represents the first known skull of a European solemydid turtle and is referred to the taxon Helochelydra nopcsai. The cranium is characterized by a number of unique traits, including a greatly reduced dorsal exposure of the prefrontal; pterygoids that completely cover the basisphenoid ventrally; a complete lack of a processus interfenestralis; and fully confluent inner and middle ear cavities. A phylogenetic analysis places He- lochelydra nopcsai close to Mongolochelys efremovi, Meiolania platyceps and Kallokibotion bajazidi just outside crown Testu- dines, but the interrelationships of these four taxa cannot be resolved with confidence. Given that the vast majority of sol- emydid turtles are known from fragmentary shell material only, we herein develop a series of typological taxon defini- tions that utilize shell sculpturing and retrieve consistent classes of fragments that originate from specific geological formations. 'Helochelydra' bakewelli and 'Helochelydra' angli- ca are removed from Solemydidae and tentatively affiliated with the pleurosternid taxon Compsemys. The holotype of the North American Naomichelys speciosa is shown to origi- nate from the Lower Cretaceous (Aptian) Kootenai Forma- tion and the fossil record of this taxon is summarized for the first time. Solemydids are known from the Berriasian- Maastrichtian of Europe and from the Aptian-Campanian of North America. The palaeoecology of solemydid turtles remains ambiguous as the presence of limb osteoderms suggests terrestrial habitat preferences whereas the flattened palate is more typical of an aquatic molluscivore.
63 citations
TL;DR: The record of turtles in the Denver Basin spans four formations (Fox Hills, Laramie, Arapahoe, and Denver) that range from Late Cretaceous (Lancian) to early Paleocene (Puercan) in age as discussed by the authors.
Abstract: The record of turtles in the Denver Basin spans four formations (Fox Hills, Laramie, Arapahoe, and Denver) that range from Late Cretaceous (Lancian) to early Paleocene (Puercan) in age. We recognize at least fifteen distinct, although fragmentary, species-level taxa, including Pleurosternidae ( Compsemys ), Baenidae ( Neurankylus, Plesiobaena, Stygiochelys , and Palatobaena ), Kinosternia ( Hoplochelys ), Adocidae ( Adocus ), Nanhsiungchelyidae ( Basilemys ), Trionychidae ( Axestemys, Aspideretoides, Helopanoplia , and another plastomenine), Macrobaenidae, and Chelydridae. Notable among these are the best-preserved skull of Compsemys , a new chelydrid genus, the most northerly confirmed record of Hoplochelys , and the most southerly records of Helopanoplia , Stygiochelys , and Macrobaenidae in the Rocky Mountain region. We also present evidence for synonymy of Paleotrionyx and Conchochelys with Axestemys , and the first cranial material assignable to Axestemys . The early Paleocene (Puercan) part of the Denver Formation yielded the most diverse assemblage, followed by the Cretaceous (Lancian) part of the Denver Formation and Laramie Formation. The Cretaceous samples are not demonstrably different from more northerly comparable faunas, but the more diverse Paleocene part of the Denver Formation exhibits a unique combination of taxa compared to contemporaneous faunas to the north and south.
60 citations
TL;DR: 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.
Abstract: The skull of the enigmatic turtle Compsemys victa Leidy, 1856 is described. A number of unique characteristics are apparent, including the extremely thick nature of all cranial bones, the presence of rod-like epipterygoids, placement of the foramen posterius canalis carotici interni halfway along the contact between the pterygoid and basisphenoid, lack of cheek emarginations, and the reduction of the size of the cavum tympani relative to the orbit. Two differing global turtle analyses and one paracryptodiran analysis were performed to determine the phylogenetic placement of C. victa. Both global analyses converged by placing C. victa within Paracryptodira, herein defined as the most inclusive clade that includes Pleurosternon bullockii and Baena arenosa, but no species of living turtle, whereas the paracryptodiran analysis places C. victa outside of Baenoidea, herein defined as the least inclusive clade that contains P. bullockii and B. arenosa. Although a number of similarities are apparent between C. victa and the uncommon, extant testudinoid Platysternon megacephalum, the available data indicate that these similarities are convergent, likely due to their carnivorous diet. Taphonomic evidence reveals that basal paracryptodires, including C. victa, preferred slow moving or ponded water environments. The riverine habitat preference of baenodds must therefore be derived.
49 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2020 | 1 |
| 2019 | 1 |
| 2018 | 1 |
| 2013 | 1 |
| 2012 | 1 |
| 2011 | 2 |