Cenozoic ichthyofaunas of the North American Western Interior, and palaeoclimatic and palaeoenvironmental reconstructions Open Access
- Other title
Cypress Hills Formation
North American Western Interior
Wood Mountain Formation
- Type of item
- Degree grantor
University of Alberta
- Author or creator
Divay, Julien D
- Supervisor and department
Murray, Alison M (Biological Sciences)
- Examining committee member and department
Proctor, Heather C (Biological Sciences)
Wilson, Mark V H (Biological Sciences)
Gringras, Murray K (Earth and Atmospheric Sciences)
Anderson, Jason S (Comparative Biology and Experimental Medicine, University of Calgary)
Brinkman, Donald B (Royal Tyrrell Museum)
Department of Biological Sciences
Systematics and Evolution
- Date accepted
- Graduation date
Doctor of Philosophy
- Degree level
The Cenozoic fluvial fish faunas of the North American Western Interior are poorly known in comparison to better preserved lake ichthyofaunas, such as that of the Green River Formation. However, fluvial fishes are typically represented by disarticulated material, which is more commonly preserved than articulated specimens, and floodplain riverine environments correspond to areas of maximal taxonomic diversity in modern freshwater environments. Therefore, disarticulated fluvial material should preserve a greater number of taxa than articulated lacustrine material, allowing a more complete understanding of the formation of the North American modern fish fauna since the Late Cretaceous.
The freshwater fishes of four North American Western Interior assemblages are here described. These assemblages were recovered from the southern Saskatchewan mid-Miocene Wood Mountain and Eo–Oligocene Cypress Hills formations, as well as the middle and early Eocene Bridger and Wasatch formations of Wyoming. The diversity of these assemblages is documented and forms the basis of palaeoclimatic and palaeoenvironmental reconstructions, founded on the specific tolerance ranges of the fish taxa present.
Both Canadian assemblages are highly diverse, typical of lowland, well-oxygenated and varied floodplain environments, and indicate warm-temperate to subtropical climates at time of deposition. The Wyoming assemblages, although also indicative of warm environments, are relatively less diverse. However, these indicate that the early Paleogene ichthyofauna of North America was similar to that of the Late Cretaceous.
Based on the comparison of the assemblages described in this thesis with one another and with other described assemblages, the evolution of the North American freshwater fish fauna through the Cenozoic is reconstructed, from the Mesozoic to the present. The turnovers that led to the formation of the modern fauna appear to have been relatively uninfluenced by the K-Pg transition, but to have occurred in two phases instead, one in the mid-Paleogene and the other in the late Neogene. These coincide with the increase of seasonality in North America between the middle and late Eocene, and the gradual cooling of climates leading to the Plio-Pleistocene glaciations, respectively.
- Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
- Citation for previous publication
Divay, J. D., and A. M. Murray. 2013. A mid-Miocene ichthyofauna from the Wood Mountain Formation, Saskatchewan, Canada. Journal of Vertebrate Paleontology 33:1269–1291.Divay, J. D., and A. M. Murray. In press. The late Eocene–early Oligocene ichthyofauna from the Eastend area of the Cypress Hills Formation, Saskatchewan, Canada. Journal of Vertebrate Paleontology.
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