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Western North America preserves iconic dinosaur faunas from the Upper Jurassic and Upper Cretaceous, but this record is interrupted by an approximately 20 Myr gap with essentially no terrestrial vertebrate fossil localities. This poorly sampled interval is nonetheless important because it is thought to include a possible mass extinction, the origin of orogenic controls on dinosaur spatial distribution, and the origin of important Upper Cretaceous dinosaur taxa. Therefore, dinosaurbearing rocks from this interval are of particular interest to vertebrate palaeontologists. In this study, we report on one such locality from Highwood Pass, Alberta. This locality has yielded a multitaxic assemblage, with the most diagnostic material identified so far including ankylosaurian osteoderms and a turtle plastron element. The fossil horizon lies within the upper part of the Pocaterra Creek Member of the Cadomin Formation (Blairmore Group). The fossils are assigned as Berriasian (earliest Cretaceous) in age, based on previous palynomorph analyses of the Pocaterra Creek Member and underlying and overlying strata. The fossils lie within numerous cross-bedded sandstone beds separated by pebble lenses. These sediments are indicative of a relatively high-energy depositional environment, and the distribution of these fossils over multiple beds indicates that they accumulated over multiple events, possibly flash floods. The fossils exhibit a range of surface weathering, having intact to heavily weathered cortices. The presence of definitive dinosaur material from near the Jurassic--Cretaceous boundary of Alberta establishes the oldest record of dinosaur body fossils in western Canada and provides a unique opportunity to study the Early Cretaceous dinosaur faunas of western North America. Key words: Ankylosauria, Berriasian, Blairmore Group, Cadomin Formation, Early Cretaceous, Kananaskis, osteoderm, Pocaterra Creek Member, Rocky Mountains, Testudines. Des assemblages de dinosaures emblematiques du Jurassique superieur au Cretace superieur sont preserves dans l'ouest de l'Amerique du Nord, mais ce registre est interrompu par une pause d'environ 20 millions d'annees caracterisee par l'absence presque totale de localites a fossiles de vertebres terrestres. Cet intervalle mal represente n'en est pas moins important parce qu'il comprendrait une possible extinction massive, l'origine de controles orogeniques de la repartition spatiale de dinosaures et l'origine d'importants taxons de dinosaures du Cretace superieur. Les roches renfermant des dinosaures de cet intervalle sont donc particulierement interessantes pour les paleontologues s'interessant aux vertebres. Nous faisons etat d'une telle localite a Highwood Pass (Alberta), qui a produit un assemblage multitaxons duquel le materiau le plus diagnostic obtenu a ce jour comprend des osteodermes ankylosauriens et un element de plastron de tortue. L'horizon fossilifere se trouve dans la partie superieure du membre de Pocaterra Creek de la Formation de Cadomin (Groupe de Blairmore). Un age berriasien (debut du Cretace) est attribue aux fossiles a la lumiere d'analyses anterieures de palynomorphes dans le membre de Pocaterra Creek et des strates sous-jacentes et sus-jacentes. Les fossiles sont presents dans de nombreux lits de gres a stratification croisee separes par des lentilles de galets. Ces sediments indiquent un milieu de depot assez dynamique, et la repartition des fossiles dans plusieurs lits indique qu'ils se sont accumules au fil de plusieurs evenements, possiblement des crues eclairs. Les fossiles presentent un eventail de types de meteorisation, montrant des cortex intacts a fortement meteorises. La presence de materiau definitivement dinosaurien a proximite de la limite Jurassique--Cretace de l'Alberta etablit la presence la plus ancienne de fossiles de corps de dinosaure dans l'Ouest canadien et offre une occasion unique d'etudier les assemblages de dinosaures du Cretace precoce de l'ouest de l'Amerique du Nord. [Traduit par la Redaction] Mots-cles : ankylosaures, Berriasien, Groupe de Blairmore, Formation de Cadomin, Cretace precoce, Kananaskis, osteoderme, membre de Pocaterra Creek, montagnes Rocheuses, testudines., Introduction The fossil record of dinosaurs is best sampled in North America, due to extensive deposits and ease of access. This is particularly the case in western North America, where [...]

Although the Jurassic was a period of high diversity in ichthyosaurs, only a small number of specimens have been recorded from Canada to date. We describe here a new occurrence of an ophthalmosaurid ichthyosaur from a shallow marine depositional environment within the Bowser Basin of northern British Columbia. Based on vertebral diameters and the size of the humerus, the ichthyosaur was relatively large compared to other contemporaneous forms, yet possessed teeth that were small for its body size. As well, the height to length ratio of the preserved vertebrae suggests it may have had a more elongate, less regionalized body shape. Although indeterminate at a generic level, the presence of Late Jurassic ichthyosaurs in nearshore waters of northwestern North America further demonstrates their cosmopolitan distribution. Si le Jurassique fut une periode de forte diversite chez les ichthyosaures, seul un petit nombre de specimens a ete enregistre au Canada a ce jour. Nous decrivons une nouvelle occurrence d'ichthyosaure ophthalmosauride d'un milieu de sedimentation marin peu profond dans le bassin de Bowser du nord de la Colombie-Britannique. A la lumiere du diametre des vertebres et de la taille des humerus, l'ichthyosaure etait relativement grand par rapport a d'autres formes contemporaines, mais possedait de petites dents pour la taille de son corps. Le rapport entre la hauteur et la longueur des vertebres preservees semble en outre indiquer une forme du corps plus allongee et moins regionalisee. Bien que le genre ne soit pas determine, la presence d'ichthyosaures au Jurassique tardif dans les eaux littorales du nord-ouest de l'Amerique du Nord constitue une nouvelle demonstration de leur repartition cosmopolite. [Traduit par la Redaction], Introduction Ichthyosaurs were a diverse and cosmopolitan group of highly aquatic marine reptiles that first appeared in the Early Triassic and survived until the Late Cretaceous (Sander 2000; McGowan and [...]

A recent survey of the middle Cenomanian Dunvegan Formation along the Peace River, Alberta, has yielded a partial skull of a large acipenseriform fish. The fossil was from an animal approximately 5min length, based on comparisons with living relatives. Though incomplete, this represents an important record of mid-Cretaceous fish from northern North America, as formations of this age are virtually unexplored in northern regions. This fossil is the oldest acipenserid from North America, and one of the most northerly known. Une etude recente de la Formation de Dunvegan du Cenomanien moyen le long de la riviere de la Paix, en Alberta, a produit un crane partiel de grand poisson acipenseriforme. A la lumiere de comparaisons avec des parents actuels, le fossile proviendrait d'un animal faisant environ 5 m de longueur. Bien qu'il soit incomplet, le specimen constitue un important exemple de poisson du Cretace moyen de l'Amerique du Nord septentrionale, les formations de cet age demeurant essentiellement non explorees dans les regions nordiques. Ce fossile est le plus ancien acipenseride d'Amerique du Nord et un des plus septentrionaux connus. [Traduit par la Redaction], Introduction Few fishes have been previously reported from the Dunvegan Formation, and the majority of these are elasmobranchs. The single osteichthyan reported, Tycheroichthys dunveganensis, is a small (about 8 cm [...]

ABSTRACT. A hadrosaurid vertebra was recovered during a palynological survey of the Upper Cretaceous Kanguk Formation in the eastern Canadian Arctic. This vertebra represents the farthest north record of any [...]

Palaeontological exploration of the Bonnet Plume Basin in northwestern Yukon Territory, Canada, has revealed a Late Paleocene to Early Eocene macrofloral assemblage from a channel fill deposit. The flora is typified by cosmopolitan taxa and dominated by deciduous angiosperms, with the notable presence of Zizyphoides, Ettingshausenia, and Corylites. Floras with a similar composition are known from Late Cretaceous through Early Eocene deposits in Alaska and the Canadian Arctic Archipelago, where they have been interpreted as evidence for warm, equable temperatures. This collection represents the most diverse known Paleogene plant macrofossil assemblage from the Yukon Territory and helps to expand our knowledge of ancient high-latitude floras. L'exploration paleontologique du bassin de Bonnet Plume, dans le nord-ouest du Yukon (Canada), a revele la presence d'un assemblage macrofloral datant du Paleocene tardif a l'Eocene precoce dans un depot de remplissage de chenal. Cette flore est caracterisee par des taxons cosmopolites et dominee par des angiospermes a feuilles caduques dont, notamment Zizyphoides, Ettingshausenia et Corylites. Des flores de composition semblable sont connues de depots allant du Cretace tardif a l'Eocene precoce de l'Alaska et des iles de l'Arctique canadien, ou leur presence a ete interpretee comme temoignant de temperatures chaudes et relativement uniformes. Cette collection represente l' assemblage de macrofossiles vegetaux paleogenes le plus diversifie du Yukon et contribue a accroitre les connaissances sur les flores anciennes de hautes latitudes. [Traduit par la Redaction], Introduction Fossil floras are some of the best empirical evidence of extreme climate change in the High Arctic and have been recognized as such for over a century (Stopes 1914; [...]

Dinosaurs and other terrestrial vertebrates are poorly documented in the Mesozoic of the Canadian polar region. Here, we provide a complete review of the Upper Cretaceous (Maastrichtian) vertebrate fauna of the Bonnet Plume Formation in the northeastern Yukon Territory, Canada, which includes the description of the first newly collected dinosaur bones from this unit in almost half a century. Previously reported fragmentary dinosaur remains collected in the early 1960's pertain to an indeterminate hadrosaurid. New material includes a poorly preserved forelimb bone and a pedal phalanx. These new remains pertain to at least one species of non-hadrosaurid ornithischian dinosaur, and the humerus is tentatively referred to a small-bodied basal ornithopod. The new vertebrate fossils from the Bonnet Plume Formation provide further evidence of vertebrates from this unit. However, directed field surveys in 2008 and 2009 suggest that vertebrate fossils are not abundant. A review of the known localities of terrestrial Mesozoic vertebrates from the Canadian Arctic indicate that it had a relatively diverse community of terrestrial vertebrates, including dinosaurs, during the Late Cretaceous, but emphasizes our limited knowledge of the Mesozoic Arctic and considerable potential for future exploration and discovery. Peu de dinosaures et d'autres vertebres terrestres sont documentes dans le Mesozoique des regions polaires canadiennes. La faune vertebree du Cretace superieur (Maastrichtien) de la Formation de Bonnet Plume, dans le nord-est du Yukon (Canada), fait l'objet d'un examen exhaustif, et les premiers nouveaux ossements de dinosaures preleves de cette unite apres pres d'un demi-siecle sont egalement decrits. Des restes fragmentaires de dinosaures recueillis au debut des annees 1960 et deja signales se rapportent a un hadrosauride indetermine. Le nouveau materiel comprend un os de membre anterieur mal preserve et une phalange pedieuse. Ces nouveaux restes se rapportent a au moins une espece de dinosaures ornithischien non hadrosauride, et l'humerus est provisoirement affecte a un ornithopode basal a petit corps. Les nouveaux fossiles de vertebres de la Formation de Bonnet Plume constituent de nouvelles preuves de la presence de vertebres dans cette unite. Des travaux de terrain diriges menes en 2008 et 2009 portent toutefois a croire que les fossiles de vertebres n'y sont pas abondants. Un examen des localites connues de vertebres terrestres mesozoiques de l'Arctique canadien indique que cette region presentait une assez grande diversite de vertebres terrestres, dont des dinosaures, au Cretace tardif, mais souligne le peu de connaissances disponibles sur l'Arctique au Mesozoique et l'important potentiel que presente cette region sur le plan de l'exploration et de decouvertes futures. [Traduit par la Redaction], Introduction Late Cretaceous and Early Paleogene high latitude terrestrial vertebrate faunas are poorly known, despite significant amounts of Late Cretaceous outcrop in the Canadian Arctic (Embry 1991; Nichols and Sweet [...]

Beta diversity is an important component of large-scale patterns of biodiversity, but its explicit examination is more difficult than that of alpha diversity. Only recently have data sets large enough been presented to begin assessing global patterns of species turnover, especially in the fossil record. We present here an analysis of beta diversity of a Maastrichtian (71-65 million years old) assemblage of dinosaurs from the Western Interior of North America, a region that covers [approximately equal to] 1.5 x [10.sup.6] [km.sup.2], borders an epicontinental sea, and spans [approximately equal to] 20[degrees] of latitude. Previous qualitative analyses have suggested regional groupings of these dinosaurs and generally concluded that there were multiple distinct faunal regions. However, these studies did not directly account for sampling bias, which may artificially decrease similarity and increase turnover between regions. Our analysis used abundance-based data to account for sampling intensity and was unable to support any hypothesis of multiple distinct faunas; earlier hypothesized faunal delineations were likely a sampling artifact. Our results indicate a low beta diversity and support a single dinosaur community within the entire Western Interior region of latest Cretaceous North America. Homogeneous environments are a known driver of low modern beta diversities, and the warm equable climate of the late Cretaceous modulated by the epicontenental seaway is inferred to be an underlying influence on the low beta diversity of this ancient ecosystem. biogeography | macroecology | paleoecology | Cretaceous doi/ 10.1073/pnas.0913645107