scholarly journals A new, transitional centrosaurine ceratopsid from the Upper Cretaceous Two Medicine Formation of Montana and the evolution of the ‘ Styracosaurus -line' dinosaurs

2020 ◽  
Vol 7 (4) ◽  
pp. 200284 ◽  
Author(s):  
John P. Wilson ◽  
Michael J. Ryan ◽  
David C. Evans
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Upper Cretaceous ◽  
Frames Of Reference ◽  
Unique Combination ◽  
Holotype Specimen ◽  
Intermediate Morphology ◽  
Northwestern Montana ◽  
Phylogenetic Framework ◽  
Stratigraphic Succession

Ceratopsids are among the most ubiquitous dinosaur taxa from the Late Cretaceous terrestrial formations of the Western Interior of North America, comprising two subfamilies, Chasmosaurinae and Centrosaurinae. The Two Medicine Formation of northwestern Montana has produced numerous remains of centrosaurine dinosaurs, which represent three taxa previously considered valid: Rubeosaurus ovatus , Einiosaurus procurvicornis and Achelousaurus horneri . Here, we reassess the previous referral of specimens to Rubeousaurus ovatus and demonstrate that this taxon is represented solely by its holotype specimen, which was first diagnosed as Styracosaurus ovatus . One of the specimens previously referred to ‘ Rubeosaurus ’ ovatus instead represents a new eucentrosauran centrosaurine taxon diagnosed here, Stellasaurus ancellae gen. et sp. nov. Stellasaurus expresses a unique combination of eucentrosauran centrosaurine characters, including an elongate nasal horncore, diminutive supraorbital horncores, and a parietal bearing straight, elongate P3 processes, semi-elongate P4 processes and non-elongate P5, P6 and P7 processes. Within the stratigraphic succession of Eucentrosaura, Stellasaurus occurs intermediate to Styracosaurus albertensis and Einiosaurus , and likewise reflects intermediate morphology. Assessed within the stratigraphic, geographical, taphonomic, ontogenetic and phylogenetic framework of Unified Frames of Reference, we fail to reject the hypothesis that Stellasaurus ancellae represents a transitional taxon within an anagenetic lineage of eucentrosauran centrosaurines.

scholarly journals The first reported ceratopsid dinosaur from eastern North America (Owl Creek Formation, Upper Cretaceous, Mississippi, USA)

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3342 ◽  
Author(s):  
Andrew A. Farke ◽  
George E. Phillips
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Depositional Environment ◽  
Upper Cretaceous ◽  
Eastern North America ◽  
Western North America ◽  
Western Interior Seaway ◽  
Double Root ◽  
Union County ◽  
Dentary Tooth

Ceratopsids (“horned dinosaurs”) are known from western North America and Asia, a distribution reflecting an inferred subaerial link between the two landmasses during the Late Cretaceous. However, this clade was previously unknown from eastern North America, presumably due to limited outcrop of the appropriate age and depositional environment as well as the separation of eastern and western North America by the Western Interior Seaway during much of the Late Cretaceous. A dentary tooth from the Owl Creek Formation (late Maastrichtian) of Union County, Mississippi, represents the first reported occurrence of Ceratopsidae from eastern North America. This tooth shows a combination of features typical of Ceratopsidae, including a double root and a prominent, blade-like carina. Based on the age of the fossil, we hypothesize that it is consistent with a dispersal of ceratopsids into eastern North America during the very latest Cretaceous, presumably after the two halves of North America were reunited following the retreat of the Western Interior Seaway.

Enigmatic teeth of small theropod dinosaurs from the Upper Cretaceous (Cenomanian–Turonian) of Uzbekistan

2013 ◽  
Vol 50 (3) ◽  
pp. 306-314 ◽  
Author(s):  
Hans-Dieter Sues ◽  
Alexander Averianov
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Upper Cretaceous ◽  
Theropod Dinosaurs ◽  
Kyzylkum Desert

Upper Cretaceous (Cenomanian–Turonian) formations in the Kyzylkum Desert of Uzbekistan, especially the Bissekty Formation at Dzharakuduk, have yielded a great diversity of continental vertebrates, including dinosaurs. Underwater screening of the sandy matrix has recovered many dinosaurian teeth. Here we describe and illustrate two types of enigmatic theropod teeth that are referable to Paronychodon and Richardoestesia, respectively. Both of these tooth taxa are well known from the Late Cretaceous of North America and possibly represent stages in the development of the teeth of various paravian theropods. Confirmation of this hypothesis awaits discovery of more complete jaws.

Probable deinonychosaur tracks from the Upper Cretaceous Wapiti Formation (upper Campanian) of Alberta, Canada

2020 ◽  
pp. 1-14
Author(s):  
Nathan J. Enriquez ◽  
Nicolás E. Campione ◽  
Corwin Sullivan ◽  
Matthew Vavrek ◽  
Robin L. Sissons ◽  
...  
Keyword(s):  
North America ◽  
Early Cretaceous ◽  
Late Cretaceous ◽  
North American ◽  
Upper Cretaceous ◽  
Temporal Window ◽  
Track Record ◽  
Important Addition ◽  
Additional Support ◽  
Upper Campanian

Abstract Late Cretaceous tracks attributable to deinonychosaurs in North America are rare, with only one occurrence of Menglongipus from Alaska and two possible, but indeterminate, occurrences reported from Mexico. Here we describe the first probable deinonychosaur tracks from Canada: a possible trackway and one isolated track on a single horizon from the Upper Cretaceous Wapiti Formation (upper Campanian) near Grande Prairie in Alberta. The presence of a relatively short digit IV differentiates these from argued dromaeosaurid tracks, suggesting the trackmaker was more likely a troodontid. Other noted characteristics of the Wapiti specimens include a rounded heel margin, the absence of a digit II proximal pad impression, and a broad, elliptical digit III. Monodactyl tracks occur in association with the didactyl tracks, mirroring similar discoveries from the Early Cretaceous Epoch of China, providing additional support for their interpretation as deinonychosaurian traces. Although we refrain from assigning the new Wapiti specimens to any ichnotaxon because of their relatively poor undertrack preservation, this discovery is an important addition to the deinonychosaur track record; it helps to fill a poorly represented geographic and temporal window in their known distribution, and demonstrates the presence of a greater North American deinonychosaur ichnodiversity than has previously been recognized.

scholarly journals The first reported ceratopsid dinosaur from eastern North America (Owl Creek Formation, Upper Cretaceous, Mississippi, USA)

2017 ◽  
Author(s):  
Andrew A. Farke ◽  
George E. Phillips
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Depositional Environment ◽  
Upper Cretaceous ◽  
Eastern North America ◽  
Western North America ◽  
Western Interior Seaway ◽  
Double Root ◽  
Union County ◽  
Dentary Tooth

Ceratopsids (“horned dinosaurs”) are known from western North America and Asia, a distribution reflecting an inferred subaerial link between the two landmasses during the Late Cretaceous. However, this clade was previously unknown from eastern North America, presumably due to limited outcrop of the appropriate age and depositional environment as well as the separation of eastern and western North America by the Western Interior Seaway during much of the Late Cretaceous. A dentary tooth from the Owl Creek Formation (late Maastrichtian) of Union County, Mississippi, represents the first reported occurrence of Ceratopsidae from eastern North America. This tooth shows a combination of features typical of Ceratopsidae, including a double root and a prominent, blade-like carina. Based on the age of the fossil, we hypothesize that it is consistent with a dispersal of ceratopsids into eastern North America during the very latest Cretaceous, presumably after the two halves of North America were reunited following the retreat of the Western Interior Seaway.

The first records of Elmisaurus (Saurischia, Theropoda) from North America

1989 ◽  
Vol 26 (6) ◽  
pp. 1319-1324 ◽  
Author(s):  
Philip J. Currie
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Genetic Similarity ◽  
Upper Cretaceous ◽  
Type Specimen ◽  
Longitudinal Ridge ◽  
Provincial Park

The discovery of a fused tarsometatarsus in the Upper Cretaceous (Campanian) strata of Dinosaur Provincial Park shows that Elmisaurus, previously known only from Mongolia, also lived in North America. Reexamination of the type specimen of "Ornithomimus" elegans (Parks 1933) confirms the identification and provides a species name. Elmisaurus elegans is more gracile than Elmisaurus rarus, has a weaker longitudinal ridge on the fourth metatarsal, and has a pair of distal processes on metatarsals II and IV. Although six theropod families had representatives in both North America and Asia during Cretaceous times, the degree of genetic similarity is poorly understood. Analysis of the Elmisaurus material suggests that faunal interchange was still underway during the Late Cretaceous.

scholarly journals The first reported ceratopsid dinosaur from eastern North America (Owl Creek Formation, Upper Cretaceous, Mississippi, USA)

2017 ◽  
Author(s):  
Andrew A. Farke ◽  
George E. Phillips
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Depositional Environment ◽  
Upper Cretaceous ◽  
Eastern North America ◽  
Western North America ◽  
Western Interior Seaway ◽  
Double Root ◽  
Union County ◽  
Dentary Tooth

Ceratopsids (“horned dinosaurs”) are known from western North America and Asia, a distribution reflecting an inferred subaerial link between the two landmasses during the Late Cretaceous. However, this clade was previously unknown from eastern North America, presumably due to limited outcrop of the appropriate age and depositional environment as well as the separation of eastern and western North America by the Western Interior Seaway during much of the Late Cretaceous. A dentary tooth from the Owl Creek Formation (late Maastrichtian) of Union County, Mississippi, represents the first reported occurrence of Ceratopsidae from eastern North America. This tooth shows a combination of features typical of Ceratopsidae, including a double root and a prominent, blade-like carina. Based on the age of the fossil, we hypothesize that it is consistent with a dispersal of ceratopsids into eastern North America during the very latest Cretaceous, presumably after the two halves of North America were reunited following the retreat of the Western Interior Seaway.

Mammals from the Upper Cretaceous Oldman Formation, Alberta. V. Eodelphis Matthew, and the evolution of the Stagodontidae (Marsupialia)

1981 ◽  
Vol 18 (2) ◽  
pp. 350-365 ◽  
Author(s):  
Richard C. Fox
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Related Species ◽  
Lower Cretaceous ◽  
Upper Cretaceous ◽  
Time Development ◽  
Special Relationship ◽  
Subsequent Increase ◽  
Closely Related Species ◽  
Primitive Species

The Judithian (Late Cretaceous) stagodontid marsupial Eodelphis Matthew is known from two closely related species, E. cutleri and E. browni, which differ in size and proportions of P3 and robustness of the molars. P1 is shown to be two-rooted in both species and not only in E. cutleri, as previously believed. Known upper molars of Eodelphis lack a stylar cusp D, indicating that neither E. cutleri nor E. browni can be a part of the direct (species) ancestry of the later Cretaceous stagodontid Didelphodon. Evolution of the Stagodontidae probably included derivation of an E. cutleri-like radicle having robust premolars and molars from E. browni-like ancestors, present in North America by Aquilan time; development by the Edmontonian of specialized crushing premolars in primitive species of Didelphodon, descended from ancestors that were similar to E. cutleri in size but had a prominent stylar cusp D on the upper molars; and subsequent increase in size leading to Lancian D. vorax and D. padanicus. Contrary to recent speculation, the Stagodontidae have no special relationship to the Lower Cretaceous Pappotheriidae, which are Eutheria.

A large pteranodontid pterosaur from the Late Cretaceous of Eastern Europe

2020 ◽  
pp. 1-13
Author(s):  
Alexander O Averianov ◽  
Maxim S Arkhangelsky
Keyword(s):  
North America ◽  
Eastern Europe ◽  
Late Cretaceous ◽  
Upper Cretaceous ◽  
The Other

Abstract The Campanian Beloe Ozero locality within the Rybushka Formation in Saratov Province, Russia, is one of the richest and most diverse Upper Cretaceous pterosaur localities in Europe. It produces identifiable remains of Pteranodontidae indet. and Azhdarchidae indet., as well as bones which can be attributed to either of these groups. The pteranodontid specimens from the Beloe Ozero locality described in this paper include a cervical III, distal scapula, humerus deltopectoral crest, proximal syncarpal, preaxial carpal and complete femur. Based on the femur and proximal syncarpal, the wingspan estimate for the Beloe Ozero pteranodontid varies from 5.2 to 6.5 m. Volgadraco bogolubovi, known from the neighbouring Shyrokii Karamysh locality of the same formation and attributed previously to the Azhdarchidae, is more likely pteranodontid than azhdarchid. The other putative records of the Pteranodontidae in the Late Cretaceous of North America, Europe and Asia are discussed. Pteranodontid pterosaurs had a much wider distribution on the northern continents in the Late Cretaceous than previously thought.

scholarly journals A small azhdarchoid pterosaur from the latest Cretaceous, the age of flying giants

2016 ◽  
Vol 3 (8) ◽  
pp. 160333 ◽  
Author(s):  
Elizabeth Martin-Silverstone ◽  
Mark P. Witton ◽  
Victoria M. Arbour ◽  
Philip J. Currie
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Fossil Record ◽  
Upper Cretaceous ◽  
Large Species ◽  
Time Of Death ◽  
The West ◽  
New Material ◽  
The Individual ◽  
Continental Interior

Pterosaur fossils from the Campanian–Maastrichtian of North America have been reported from the continental interior, but few have been described from the west coast. The first pterosaur from the Campanian Northumberland Formation (Nanaimo Group) of Hornby Island, British Columbia, is represented here by a humerus, dorsal vertebrae (including three fused notarial vertebrae), and other fragments. The elements have features typical of Azhdarchoidea, an identification consistent with dominance of this group in the latest Cretaceous. The new material is significant for its size and ontogenetic stage: the humerus and vertebrae indicate a wingspan of ca 1.5 m, but histological sections and bone fusions indicate the individual was approaching maturity at time of death. Pterosaurs of this size are exceedingly rare in Upper Cretaceous strata, a phenomenon commonly attributed to smaller pterosaurs becoming extinct in the Late Cretaceous as part of a reduction in pterosaur diversity and disparity. The absence of small juveniles of large species—which must have existed—in the fossil record is evidence of a preservational bias against small pterosaurs in the Late Cretaceous, and caution should be applied to any interpretation of latest Cretaceous pterosaur diversity and success.

Angiosperm wood from the Upper Cretaceous (Coniacian) of British Columbia, Canada

IAWA Journal ◽  
2017 ◽  
Vol 38 (2) ◽  
pp. 141-161 ◽  
Author(s):  
Nathan A. Jud ◽  
Elisabeth A. Wheeler ◽  
Gar W. Rothwell ◽  
Ruth A. Stockey
Keyword(s):  
British Columbia ◽  
North America ◽  
Late Cretaceous ◽  
Upper Cretaceous ◽  
Vancouver Island ◽  
Growth Rings ◽  
Thin Sections ◽  
Marine Deposits ◽  
Dry Wood ◽  
Cretaceous Deposits

Fossil angiosperm wood was collected from shallow marine deposits in the Upper Cretaceous (Coniacian) Comox Formation on Vancouver Island, British Columbia, Canada. The largest specimen is a log at least 2 m long and 38 cm in diameter. Thin sections from a sample of this log reveal diffuseporous wood with indistinct growth rings and anatomy similar toParaphyllanthoxylon. Occasional idioblasts with dark contents in the rays distinguish this wood from previously knownParaphyllanthoxylonspecies and suggest affinity with Lauraceae. The log also includes galleries filled with dry-wood termite coprolites. This trunk reveals the presence of tree-sized angiosperms in what is now British Columbia, and the association of dry-wood termites with angiosperm woods by the Coniacian (89 Ma). To understand the significance of this discovery, we reviewed the record of Cretaceous woods from North America. Our analysis of the distribution of fossil wood occurrences from Cretaceous deposits supports the conclusion that there was a strong latitudinal gradient in both the size and distribution of angiosperm trees during the Late Cretaceous, with no reports of Cretaceous angiosperm trees north of 50°N paleo-latitude in North America. The rarity of angiosperm wood in the Cretaceous has long been used to support the idea that flowering plants were generally of low-stature for much of the Cretaceous; however, large-stature trees withParaphyllanthoxylon-like wood anatomy were widespread at lower–middle paleo-latitudes at least in North America during the Late Cretaceous. Thus, the presence of a largeParaphyllanthoxylonlog in the Comox Formation suggests that Vancouver Island has moved significantly northward since the Coniacian as indicated by other geological and paleobotanical studies.

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