{"title":"第三章:加拿大西部前陆盆地上白垩世(coniian - santonian)的舟形菊石","authors":"N. Landman, A. Plint, I. Walaszczyk","doi":"10.1206/0003-0090-414.1.1","DOIUrl":null,"url":null,"abstract":"ABSTRACT The Upper Cretaceous (Coniacian-Santonian) of the Western Canada Foreland Basin, contains a rich record of scaphitid ammonites (scaphites). We describe four species: Scaphites (Scaphites) preventricosus Cobban, 1952, Scaphites (S.) ventricosus Meek and Hayden, 1862, Scaphites (S.) depressus Reeside, 1927, and Clioscaphites saxitonianus (McLearn, 1929). These are widespread index fossils that demarcate the upper lower-middle, middle, and upper Coniacian, and the lower Santonian, respectively. They occur in the lower part of the Wapiabi Formation, Alberta. The Coniacian part of the section has been divided into 24 informal allomembers based on the recognition of marine flooding surfaces, most of which can be traced through the >750 km extent of the study area. The most distinctive feature in the ontogenetic development of scaphites is the change in coiling during ontogeny. At the approach of maturity, the shell uncoils slightly, forming a shaft, which then recurves backward approaching the earlier secreted phragmocone. However, this sequence of scaphites shows an evolutionary trend toward recoiling, accompanied by an increase in size and degree of depression. These changes occurred against a background of changing environmental conditions resulting from the expansion of the Western Interior Seaway during the Niobrara transgression. This resulted in an increase in the area of offshore habitats, which may have promoted the appearance of larger species with more depressed whorl sections. Scaphites probably lived at depths of less than 100 m, and may have fed on small organisms in the water column.","PeriodicalId":50721,"journal":{"name":"Bulletin of the American Museum of Natural History","volume":"1 1","pages":"105 - 172"},"PeriodicalIF":5.1000,"publicationDate":"2017-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1206/0003-0090-414.1.1","citationCount":"7","resultStr":"{\"title\":\"Chapter 3: Scaphitid Ammonites from the Upper Cretaceous (Coniacian-Santonian) Western Canada Foreland Basin\",\"authors\":\"N. Landman, A. Plint, I. Walaszczyk\",\"doi\":\"10.1206/0003-0090-414.1.1\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"ABSTRACT The Upper Cretaceous (Coniacian-Santonian) of the Western Canada Foreland Basin, contains a rich record of scaphitid ammonites (scaphites). We describe four species: Scaphites (Scaphites) preventricosus Cobban, 1952, Scaphites (S.) ventricosus Meek and Hayden, 1862, Scaphites (S.) depressus Reeside, 1927, and Clioscaphites saxitonianus (McLearn, 1929). These are widespread index fossils that demarcate the upper lower-middle, middle, and upper Coniacian, and the lower Santonian, respectively. They occur in the lower part of the Wapiabi Formation, Alberta. The Coniacian part of the section has been divided into 24 informal allomembers based on the recognition of marine flooding surfaces, most of which can be traced through the >750 km extent of the study area. The most distinctive feature in the ontogenetic development of scaphites is the change in coiling during ontogeny. At the approach of maturity, the shell uncoils slightly, forming a shaft, which then recurves backward approaching the earlier secreted phragmocone. However, this sequence of scaphites shows an evolutionary trend toward recoiling, accompanied by an increase in size and degree of depression. These changes occurred against a background of changing environmental conditions resulting from the expansion of the Western Interior Seaway during the Niobrara transgression. This resulted in an increase in the area of offshore habitats, which may have promoted the appearance of larger species with more depressed whorl sections. Scaphites probably lived at depths of less than 100 m, and may have fed on small organisms in the water column.\",\"PeriodicalId\":50721,\"journal\":{\"name\":\"Bulletin of the American Museum of Natural History\",\"volume\":\"1 1\",\"pages\":\"105 - 172\"},\"PeriodicalIF\":5.1000,\"publicationDate\":\"2017-06-26\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://sci-hub-pdf.com/10.1206/0003-0090-414.1.1\",\"citationCount\":\"7\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Bulletin of the American Museum of Natural History\",\"FirstCategoryId\":\"93\",\"ListUrlMain\":\"https://doi.org/10.1206/0003-0090-414.1.1\",\"RegionNum\":2,\"RegionCategory\":\"环境科学与生态学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"BIODIVERSITY CONSERVATION\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Bulletin of the American Museum of Natural History","FirstCategoryId":"93","ListUrlMain":"https://doi.org/10.1206/0003-0090-414.1.1","RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"BIODIVERSITY CONSERVATION","Score":null,"Total":0}
Chapter 3: Scaphitid Ammonites from the Upper Cretaceous (Coniacian-Santonian) Western Canada Foreland Basin
ABSTRACT The Upper Cretaceous (Coniacian-Santonian) of the Western Canada Foreland Basin, contains a rich record of scaphitid ammonites (scaphites). We describe four species: Scaphites (Scaphites) preventricosus Cobban, 1952, Scaphites (S.) ventricosus Meek and Hayden, 1862, Scaphites (S.) depressus Reeside, 1927, and Clioscaphites saxitonianus (McLearn, 1929). These are widespread index fossils that demarcate the upper lower-middle, middle, and upper Coniacian, and the lower Santonian, respectively. They occur in the lower part of the Wapiabi Formation, Alberta. The Coniacian part of the section has been divided into 24 informal allomembers based on the recognition of marine flooding surfaces, most of which can be traced through the >750 km extent of the study area. The most distinctive feature in the ontogenetic development of scaphites is the change in coiling during ontogeny. At the approach of maturity, the shell uncoils slightly, forming a shaft, which then recurves backward approaching the earlier secreted phragmocone. However, this sequence of scaphites shows an evolutionary trend toward recoiling, accompanied by an increase in size and degree of depression. These changes occurred against a background of changing environmental conditions resulting from the expansion of the Western Interior Seaway during the Niobrara transgression. This resulted in an increase in the area of offshore habitats, which may have promoted the appearance of larger species with more depressed whorl sections. Scaphites probably lived at depths of less than 100 m, and may have fed on small organisms in the water column.
期刊介绍:
The Bulletin, published continuously since 1881, consists of longer monographic volumes in the field of natural sciences relating to zoology, paleontology, and geology. Current numbers are published at irregular intervals. The Bulletin was originally a place to publish short papers, while longer works appeared in the Memoirs. However, in the 1920s, the Memoirs ceased and the Bulletin series began publishing longer papers. A new series, the Novitates, published short papers describing new forms.