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 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.

A new bird from the Upper Cretaceous Two Medicine Formation of Montana

2002 ◽  
Vol 39 (1) ◽  
pp. 19-26 ◽  
Author(s):  
David J Varricchio
Keyword(s):  
Late Cretaceous ◽  
Upper Cretaceous ◽  
New Genus ◽  
Articular Surface ◽  
Type Specimen ◽  
Depositional Environments ◽  
Western Montana ◽  
New Genus And Species ◽  
Basal Position

A partial humerus, ulna, and radius compose the type specimen of a new bird, Piksi barbarulna, new genus and species, from the Late Cretaceous (Campanian) Two Medicine Formation of western Montana. This ornithothoracine taxon differs from all other birds in having an enlarged dorsal epicondyle and a reduced ventral condyle on the humerus with corresponding modifications on the articular surface of the ulna. Among modern birds, Piksi is most similar to galliforms, but the paucity of unambiguous characters and its unusual morphology defy placement within any extant "order" and strongly questions any neornithine affinities. Instead, Piksi appears to have a fairly basal position within Ornithothoraces. Several morphologic features of Piksi occur in phylogenetically diverse but morphologically similar birds, such as galliforms, tinamous, and some columbiforms. The new bird comes from an inland, relatively dry paleo-environment. Atypical for a Cretaceous avian record dominated by waterfowl, Piksi appears to represents a heavy-bodied ground bird. Searching of inland depositional environments may yield new and ecologically distinct avian varieties.

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.

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.

The Late Cretaceous shark Ptychodus marginalis in the Western Interior Seaway, USA

2010 ◽  
Vol 84 (3) ◽  
pp. 538-548 ◽  
Author(s):  
Shawn A. Hamm
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Type Specimen ◽  
Tooth Crown ◽  
Western Interior Seaway ◽  
Tooth Morphology

Re-evaluation of teeth referred to the Late Cretaceous shark Ptychodus polygyrus from North America are hereby determined to be synonymous with another species having similar tooth morphology, Ptychodus marginalis Agassiz. Ptychodus marginalis differs from P. polygyrus by having an elevated and rounded tooth crown with transverse ridges restricted centrally on the apex of the crown with a clearly defined marginal area. The type specimen of P. marginalis was described from Middle Cenomanian to Middle Turonian deposits in the English Chalk, and teeth possessing identical tooth morphologies are found within contemporary units in North America, whereas teeth having the typical P. polygyrus morphology are restricted to Late Santonian-Early Campanian deposits.

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.

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