New material of Gilmoremys lancensis nov. comb. (Testudines: Trionychidae) from the Hell Creek Formation and the diagnosis of plastomenid turtles

2011 ◽  
Vol 85 (3) ◽  
pp. 442-459 ◽  
Author(s):  
Walter G. Joyce ◽  
Tyler R. Lyson
Keyword(s):  
Phylogenetic Analysis ◽  
North America ◽  
North Dakota ◽  
Late Cretaceous ◽  
Hell Creek Formation ◽  
Secondary Palate ◽  
New Material

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 elongate sinusoidal grooves, distally expanded second costals, hyoplastral shoulders, an extensive secondary palate with accessory ridges, an extremely elongate mandible, a contribution of the parietal to the wall of the orbit, and a posterior ossified narial canal. 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 plastomenid turtles, in particular the contribution of the parietal to the orbit wall and the extensive secondary palate. All plastomenid turtles with a locked entoplastron are placed in Hutchemys. Assuming that all taxa are monophyletic, the phylogenetic analysis implies that the G. lancensis lineage is the only one to go extinct at the K/T boundary, whereas the four remaining plastomenid lineages survive. Extensive ghost ranges are nevertheless apparent. Taphonomic considerations indicate that G. lancensis was a riverine turtle, whereas more derived plastomenids preferred swampy habitats.

scholarly journals The shell morphology of the latest Cretaceous (Maastrichtian) trionychid turtle Helopanoplia distincta

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e4169 ◽  
Author(s):  
Walter G. Joyce ◽  
Tyler R. Lyson
Keyword(s):  
Phylogenetic Analysis ◽  
North Dakota ◽  
Late Cretaceous ◽  
Type Specimen ◽  
Shell Morphology ◽  
Surface Sculpture ◽  
Fine Grained ◽  
Hell Creek Formation ◽  
The Past ◽  
Metaplastic Bone

Background Helopanoplia distincta is an extinct soft-shelled turtle (Pan-Trionychidae) for which the type specimen is a fragmentary costal and the inguinal notch portion of the left hypoplastron from the Late Cretaceous (Maastrichtian) Lance Formation of Wyoming, USA that bear a distinct surface sculpture pattern consisting of raised tubercles. Over the course of the past few decades, a number of additional, fragmentary specimens from the Late Cretaceous (Maastrichtian) Hell Creek Formation of Montana and North Dakota have been referred to this taxon based on the presence of these tubercles, but a more complete understanding of the anatomy and phylogenetic relationships of this distinctive soft-shelled turtle is still outstanding. Methods We here figure and describe shell remains of eight fossils referable to Helopanoplia distincta from the Hell Creek Formation of Montana and North Dakota that, in combination, document nearly all aspects of the shell morphology of this taxon. We furthermore explore the relationships of this fossil turtle by inserting it into a modified phylogenetic analysis of pan-trionychid relationships. Results The new fossil material thoroughly supports the validity of Helopanoplia distincta. In addition to its unique surface sculpture pattern, this turtle can be diagnosed relative to all other named pan-trionychids by the presence of a distinct corner along the margin of costals II, the complete covering of costal ribs I–VI by metaplastic bone, midline contact of the main plastral elements, hyoplastral shoulder, presence of a lateral, upturned margin on the hyo/hypoplastron that is covered dorsally and laterally by sculptured metaplastic bone, a single, lateral hyoplastral process, and the apomorphic presence of fine scallops along the margin of costals VIII, formation of a laterally embraced, rounded nuchal, anteriorly rounded costals I, distally expanded costals II, and narrow costals VII. A phylogenetic analysis places Helopanoplia distincta as sister to the clade formed by Plastomenus thomasii and Hutchemys spp., thereby confirming its identity as a plastomenid. The vast majority of Helopanoplia distincta material has been recovered from fine-grained overbank deposits, thereby supporting the hypothesis that this turtle favored ponded waters.

scholarly journals A tyrannosauroid metatarsus from the Merchantville formation of Delaware increases the diversity of non-tyrannosaurid tyrannosauroids on Appalachia

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e4123 ◽  
Author(s):  
Chase D. Brownstein
Keyword(s):  
Phylogenetic Analysis ◽  
North America ◽  
Late Cretaceous ◽  
Fossil Record ◽  
Morphological Features ◽  
The West ◽  
Intermediate Grade

During the Late Cretaceous, the continent of North America was divided into two sections: Laramidia in the west and Appalachia in the east. Although the sediments of Appalachia recorded only a sparse fossil record of dinosaurs, the dinosaur faunas of this landmass were different in composition from those of Laramidia. Represented by at least two taxa (Appalachiosaurus montgomeriensis and Dryptosaurus aquilunguis), partial and fragmentary skeletons, and isolated bones, the non-tyrannosaurid tyrannosauroids of the landmass have attracted some attention. Unfortunately, these eastern tyrants are poorly known compared to their western contemporaries. Here, one specimen, the partial metatarsus of a tyrannosauroid from the Campanian Merchantville Formation of Delaware, is described in detail. The specimen can be distinguished from A. montgomeriensis and D. aquilunguis by several morphological features. As such, the specimen represents a potentially previously unrecognized taxon of tyrannosauroid from Appalachia, increasing the diversity of the clade on the landmass. Phylogenetic analysis and the morphology of the bones suggest the Merchantville specimen is a tyrannosauroid of “intermediate” grade, thus supporting the notion that Appalachia was a refugium for relict dinosaur clades.

Systematics and paleobiogeographic significance of the Upper Ordovician pterygometopine trilobiteAchatellaDelo, 1935

2016 ◽  
Vol 90 (1) ◽  
pp. 59-77 ◽  
Author(s):  
Robert E. Swisher ◽  
Stephen R. Westrop ◽  
Lisa Amati
Keyword(s):  
United States ◽  
Phylogenetic Analysis ◽  
North America ◽  
Northern Ireland ◽  
Northeastern United States ◽  
Upper Ordovician ◽  
Additional Species ◽  
Middle Ordovician ◽  
New Material ◽  
Migration Event

AbstractStudy of type and new material of the pterygometopineAchatellaDelo, 1935 demonstrates the presence of four species in Upper Ordovician (Katian) strata of Laurentian North America,A.achates(Billings, 1860) from the northeastern United States and the St. Lawrence lowlands of Canada,A.carleyi(Meek, 1872) from the Cincinnati region, Ohio and Kentucky,A.katharina(Bradley, 1930), from Missouri and Oklahoma, andA.clivosaLespérance and Weissenberger, 1998 from the Gaspé Peninsula, Quebec. Perhaps as many as five additional species are present in Sandbian–Katian strata of the Laurentian terranes of Scotland and Northern Ireland, although only three of these are known well enough to code for phylogenetic analysis. The oldest pterygometopines, including species ofAchatella, are known from Middle Ordovician strata of Baltica. Phylogenetic analysis supports a single migration event from Baltica from Laurentia, followed by a modest diversification in the latter region.

scholarly journals Prootic anatomy of a juvenile tyrannosauroid from New Jersey and its implications for the morphology and evolution of the tyrannosauroid braincase

2018 ◽  
Author(s):  
Chase D Brownstein
Keyword(s):  
Phylogenetic Analysis ◽  
North America ◽  
Northern Hemisphere ◽  
Late Cretaceous ◽  
Coastal Plain ◽  
Fossil Record ◽  
Atlantic Coastal Plain ◽  
Western Interior Seaway ◽  
Large Predator ◽  
Atlantic Coastal

Among the most recognizable theropods are the tyrannosauroids, a group of small to large carnivorous coelurosaurian dinosaurs that inhabited the majority of the northern hemisphere during the Cretaceous and came to dominate large predator niches in North American and Asian ecosystems by the end of the Mesozoic era. The clade is among the best-represented of dinosaur groups in the notoriously sparse fossil record of Appalachia, the Late Cretaceous landmass that occupied the eastern portion of North America after its formation from the transgression of the Western Interior Seaway. Here, the prootic of a juvenile tyrannosauroid collected from the middle-late Campanian Marshalltown Formation of the Atlantic Coastal Plain is described, remarkable for being the first concrete evidence of juvenile theropods in that plain during the time of the existence of Appalachia and the only portion of theropod braincase known from the landmass. Phylogenetic analysis recovers the specimen as an “intermediate” tyrannosauroid of similar grade to Dryptosaurus and Appalachiosaurus. Comparisons with the corresponding portions of other tyrannosauroid braincases suggest that the Ellisdale prootic is more similar to Turonian forms in morphology than to the derived tyrannosaurids of the Late Cretaceous, thus supporting the hypothesis that Appalachian tyrannosauroids and other vertebrates were relict forms surviving in isolation from their derived counterparts in Eurasia.

E.D. Cope's 1893 Expedition to the Dakotas Revisited

1990 ◽  
Vol 9 (1) ◽  
pp. 57-61
Author(s):  
Anthony Fiorillo ◽  
Edward Daeschler
Keyword(s):  
South Dakota ◽  
North Dakota ◽  
Late Cretaceous ◽  
Natural Sciences ◽  
Vertebrate Paleontology ◽  
Hell Creek Formation ◽  
Insight Into ◽  
Academy Of Natural Sciences

Recently an uncatalogued cache of fossil reptile material was discovered in the vertebrate paleontology collection at the Academy of Natural Sciences of Philadelphia. Evidence obtained from handwritten notes on the newspaper in which the specimens were wrapped indicates that the specimens are part of the collection made by Edward Drinker Cope on his expedition to the Dakotas and Oklahoma in 1893. These fossils were collected in the vicinity of Fort Yates, North Dakota, and Hump Creek, South Dakota, and are predominantly from the Hell Creek Formation (Maastrichtian: Late Cretaceous). No fossils from the Oklahoma segment of Cope's journey were found in the collection. Details of the Dakota segment of the expedition are reconstructed from correspondence written by Cope while he was in the field and from notes on some of the field wrappings of these newly discovered specimens. These materials are significant to the Academy of Natural Sciences since they provide insight into an aspect of Academy history which had been previously lost.

A new kinosternoid from the Late Cretaceous Hell Creek Formation of North Dakota and Montana and the origin of the Dermatemys mawii lineage

PalZ ◽  
2010 ◽  
Vol 85 (2) ◽  
pp. 125-142 ◽  
Author(s):  
Georgia E. Knauss ◽  
Walter G. Joyce ◽  
Tyler R. Lyson ◽  
Dean Pearson
Keyword(s):  
North Dakota ◽  
Late Cretaceous ◽  
Hell Creek Formation

A review of Leidyosuchus canadensis Lambe, 1907 (Archosauria: Crocodylia) and an assessment of cranial variation based upon new material

2001 ◽  
Vol 38 (12) ◽  
pp. 1665-1687 ◽  
Author(s):  
Xiao-Chun Wu ◽  
Anthony P Russell ◽  
Donald B Brinkman
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Individual Variation ◽  
The Other ◽  
Cranial Morphology ◽  
Cranial Variation ◽  
New Information ◽  
New Material ◽  
Incisive Foramen ◽  
Two Stages

Cranial morphology of Leidyosuchus canadensis Lambe 1907 is reviewed based on previously undescribed material—seven skulls and eight mandibles. This species can be distinctively diagnosed by more than 10 derived features. New information supports the contention that L. canadensis is the sole representative of Leidyosuchus, and indicates that it is very different from the other species previously assigned to this taxon. The membership of L. canadensis within Alligatoroidea is also demonstrated by new information revealed in this study. Ontogenetic and individual variation in the cranial anatomy of L. canadensis are documented. The contact of the premaxillary–maxillary suture with the incisive foramen is not diagnostic of the taxon; rather, it exhibits individual variation. Leidyosuchus is endemic to North America. There was no faunal interchange of crocodyliforms between North America and central Asia during the last two stages of the Late Cretaceous.

scholarly journals A remarkable short-snouted horned dinosaur from the Late Cretaceous (late Campanian) of southern Laramidia

2013 ◽  
Vol 280 (1766) ◽  
pp. 20131186 ◽  
Author(s):  
Scott D. Sampson ◽  
Eric K. Lund ◽  
Mark A. Loewen ◽  
Andrew A. Farke ◽  
Katherine E. Clayton
Keyword(s):  
Phylogenetic Analysis ◽  
North America ◽  
Late Cretaceous ◽  
Fossil Record ◽  
Strong Support ◽  
Northern Region ◽  
New Taxon ◽  
Western North America ◽  
Postcranial Skeleton ◽  
Western Interior Seaway

The fossil record of centrosaurine ceratopsids is largely restricted to the northern region of western North America (Alberta, Montana and Alaska). Exceptions consist of single taxa from Utah ( Diabloceratops ) and China ( Sinoceratops ), plus otherwise fragmentary remains from the southern Western Interior of North America. Here, we describe a remarkable new taxon, Nasutoceratops titusi n. gen. et sp., from the late Campanian Kaiparowits Formation of Utah, represented by multiple specimens, including a nearly complete skull and partial postcranial skeleton. Autapomorphies include an enlarged narial region, pneumatic nasal ornamentation, abbreviated snout and elongate, rostrolaterally directed supraorbital horncores. The subrectangular parietosquamosal frill is relatively unadorned and broadest in the mid-region. A phylogenetic analysis indicates that Nasutoceratops is the sister taxon to Avaceratops , and that a previously unknown subclade of centrosaurines branched off early in the group's history and persisted for several million years during the late Campanian. As the first well-represented southern centrosaurine comparable in age to the bulk of northern forms, Nasutoceratops provides strong support for the provincialism hypothesis, which posits that Laramidia—the western landmass formed by inundation of the central region of North America by the Western Interior Seaway—hosted at least two coeval dinosaur communities for over a million years of late Campanian time.

Sign in / Sign up

Export Citation Format

Share Document