The composition and paleoecology of Crassostrea bioassemblages in the Horshoe Canyon and St. Mary River formations (Upper Cretaceous), South Central Alberta, Canada
Notice bibliographique
Résumé
Living populations of the oysters Crassostrea virginica and Crassostrea gigas occupying several environmental situations are used to revise the taxonomy of the Cretaceous oysters Crassostrea subtrigonalis and Crassostrea glabra; and to interpret the paleogeographic settings of various Late Cretaceous oyster beds exposed in south-central Alberta, Canada. Valves of the modem oysters Crassostrea virginica and Crassostrea gigas are described herein: the former from North Inlet, South Carolina, and from Copano and Aransas Bays, Texas; the latter from the Pacific coastline of North America. Varied and abundant valves of Crassostrea subtrigonalis are described from the Horseshoe Canyon and St Mary River formations (both Upper Cretaceous) of south-central Alberta. Analyses and comparisons of the measurements of the right valve of modem and Cretaceous oysters indicate that a single species - C subtrigonalis - occurs in the Cretaceous study region; it is characterized by a resilifer length/hingeline length ratio of 2.0-2.4 (mean 2.19). Crassostrea glabra is judged to be a junior synonym of C. subtrigonalis. Variations in the size, shape, and convexity of the left valve of the modem and Cretaceous oysters facilitate recognition of ecophenotypes of C. subtrigonalis indicative of subaerial exposure, salinity, rates of sedimentation, and food supply. Accordingly, the six C. subtrigonalis ecophenotypes recognized can be characterized as follows: Ecophenotype T: third-order tidal creeks dissecting the high marsh; Ecophenotype S: second-order tidal creeks dissecting the low marsh; Ecophenotype F: first-order tidal creeks flowing through low marsh from nonmarine to marine environments; Ecophenotype uE: upper estuary; Ecophenotype IE: lower estuary; and Ecophenotype L: lagoons with strong marine influence. The detailed stratigraphy and faunal composition of the oyster beds in the following seven study areas of south-central Alberta are described: Willow Creek, Drumheller, Queenstown, Travers Reservoir, Monarch Fault Zone, Magrath, and Del Bonita. The invertebrate fauna associated with Crassostrea subtrigonalis is usually very limited. The following taxa have been identified and discussed herein: bivalves, Mya (A.) simulatrix, Brachidontes (B.) dichotoma, Modiolus (M.) galpinianus, Corbicula (C.) occidentalis, C (C.) ventricosa, C. (C.) obliquata, Anomia (A.) perstrigosa, Corbula (C.) perangulata, and C. (C.) subtrigonalis; gastropods, Euspira obliquata, Pachymelania wyomingensis, and Viviparus mokowanesis; bryozoans, Eokotosokum bicystosum and Villicharixa lintonensis; ostracods, Cypridea sp. and Pontocypris sp.; and ichnofossils, Entobia cretacea and Oichnus simplex. Within each study area, distinctive associations of the Crassostrea subtrigonalis ecophenotypes with particular species enable definition of recurring bioassemblages. The latter are considered to characterize specific environments within the study areas. Two sedimentary models proposed for the Willow Creek and Drumheller areas reflect depositional and ecological conditions interpreted from the lateral and vertical distribution of the bioassemblages. The Willow Creek Model represents a system of three orders of tidal creeks dissecting a salt marsh. The Drumheller Marine Tongue Model incorporates a series of oyster accumulations of ecophenotypes uE, IE, and L that are distributed distally within an estuary. These models are applied to interpret the remaining five study areas. The Queenstown, Monarch Fault Zone, and Del Bonita study areas are similar to the Drumheller Marine Tongue Model; while the Travers Reservoir and Magrath study areas are consonant with the Willow Creek Model. The significance of this study lies in (a) specifying criteria enabling unequivocal recognition of Crassostrea subtrigonalis; (b) defining and interpreting the significance of ecophenotypes; and (c) constmcting the Willow Creek and the Dmmheller sedimentaryecological models that may be used for the interpretation of quantitatively varied occurrences of species of Crassostrea.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».