GEOSCAN, résultats de la recherche


TitreFirst record of a Cretaceous plesiosaur from the Yukon Territory
AuteurCampbell, J A; Haggart, J W; Druckenmiller, P S; Schröder-Adams, C J; Zazula, G; Ryan, M J
SourceCanadian Paleontology Conference Program and Abstracts no. 10, 2012 p. 20
Séries alt.Secteur des sciences de la Terre, Contribution externe 20120258
RéunionCanadian Paleontology Conference; Toronto, ON; CA; Septembre 21-23, 2012
Documentpublication en série
Sujetsassemblages fossiles; distribution de fossiles; fossiles; Albien; Formation d'Arctic Red ; paléontologie; Mésozoïque; Crétacé
ProgrammeBassins sédimentaires du Yukon, GEM : La géocartographie de l'énergie et des minéraux
Résumé(disponible en anglais seulement)
An isolated vertebra surface collected from marine shales of the Albian (Lower Cretaceous) Arctic Red Formation along the Road River represents the first documented occurrence of a plesiosaur from the Yukon Territory. The specimen is approximately four cm wide, 3 cm high, and 3 cm in length, with oval, platycoelous articular surfaces, and probably represents a cervical centrum with eroded rib facets. Two low-relief, parallel, longitudinal ridges on the dorsal surface define the lateral margins of the neural canal. Two small foramina subcentralia are present on the ventral surface. This latter feature is present in most plesiosaurians and in only a few Triassic non-plesiosaurian sauropterygians. Although its taxonomic position is uncertain, the specimen cannot be assigned to Elasmosauridae as the cervical centra of these taxa are longer than tall and bear a notch on the ventral margin of the articular facet.
The ammonites Beudanticeras glabrum and cf. Arcthoplites cf. aburense associated with the plesiosaur centrum place it in the Beudanticeras affine Zone of the northern Cordillera, indicating a late Early to early Late Albian age for the specimen (approximately 105-107 Ma). This age corresponds to that of the Joli Fou Seaway, the only phase of the Albian Western Interior Seaway that connected with the warm Tethyan Sea; all other phases only received water from the cooler Boreal Sea. Based on this inference, we suggest that the Joli Fou Seaway portion of the Arctic Red Formation may be found to contain a unique, warm water marine reptile fauna within the Albian Western Interior Seaway, when more specimens are recovered.
Previously collected, but unreported, marine reptile fossils from the Yukon include six ribs in the collections of the Canadian Museum of Nature from a Lower Cretaceous marine shale unit (formation unknown) in the northern Peel River region, and an ichthyosaur centrum in the collections of the MacBride Museum of Yukon History from the Lower to Middle Triassic Toad Formation in the Beaver River region. These specimens have important implications for the paleobiogeography of marine reptiles that were present in what is now the Canadian Arctic.