Vertebrate Biostratigraphy of the Smoky Hill Chalk (Niobrara Formation) and the Sharon Springs Member (Pierre Shale)
2008; Springer Nature; Linguagem: Inglês
10.1007/978-1-4020-9053-0_11
ISSN2452-1639
Autores Tópico(s)Fish biology, ecology, and behavior
ResumoThroughout much of the Western Interior of North America there is a thick sequence of Upper Cretaceous marine rocks, which in places exceeds 6000 m (Weimer 1983). These sediments record a meridional seaway that connected the Gulf of Mexico to the Arctic Ocean during the Late Cretaceous. Marine vertebrate fossils are extremely common in some of these beds, especially in the Smoky Hill Chalk Member of the Niobrara Formation and in the overlying Sharon Springs Member of the Pierre Shale. Most specimen collecting has concentrated on the Smoky Hill Chalk because of the exquisite quality of the fossils. As a result, there is a large volume of literature that spans over 100 years (e.g., Cope 1875; Williston 1906; Goody 1970). Unfortunately, however, most collections have treated the Smoky Hill as a single fauna, despite early evidence to the contrary (e.g., Williston 1897). Recently, attempts have been undertaken to determine the biostratigraphic distribution of the various vertebrate taxa (Stewart 1988, 1990a; Bennett 1990, 2000; Sheldon 1996; Everhart 2001) and this has provided insights into the faunal changes that have occurred (Carpenter 1990, 1996a, also below; Sheldon 1996).
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