Diversity and structure of Late Cretaceous–Paleogene crocodyliform communities in southern Saskatchewan, Canada
Date
2024-07-24
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
0000-0002-0693-0730
Type
Thesis
Degree Level
Masters
Abstract
Crocodyliform fossils of extinct relatives and members of modern families are common finds in southern Saskatchewan, Canada, spanning a largely continuous interval of the Upper Cretaceous and Paleogene. Although this location represents the northernmost known extent of many well-known taxa, only a few individuals are documented in the literature, demonstrating the importance of Saskatchewan to the study of early crown-group crocodylians from the area. This study approaches these fossil crocodyliforms from multiple angles; describing previously unpublished specimens, examining the stratigraphy and taphonomy of the most notable quarries, and identifying patterns of the microvertebrate sites of the latest Maastrichtian Frenchman Formation in a case study to learn about the composition, ecology, and taphonomic overprints of this crocodyliform community. Almost all crocodyliforms known from Alberta and the northern United States over the span of the Campanian to late Eocene are confirmed to be (or are likely) present in Saskatchewan, including multiple species of Borealosuchus, and various alligatoroid genera. Borealosuchus is the most common and longest-lived crocodyliform represented, persisting in Saskatchewan from about 66.3 to 59 million years ago. This genus is preserved in a variety of freshwater habitats over this time interval, demonstrating resilience and flexibility in the face of ecosystem changes that occurred across the Cretaceous–Paleogene (K–Pg) boundary and well into the Paleocene. Most Frenchman Formation microsites show an elevated number of osteoderms and teeth compared to fragments of skeletal material. This likely represents a preservation bias due to each individual animal having hundreds of osteoderms and teeth. Additionally, the smaller teeth are the most common, likely representing an abundance of small and/or young individuals shedding teeth at a greater rate. This resembles the population structure in other extinct and modern crocodyliform communities, suggesting similar life histories.
Description
Keywords
crocodyliform, crocodyliformes, Saskatchewan, Canada, crocodylian, Cretaceous, Paleogene, diversity
Citation
Degree
Master of Science (M.Sc.)
Department
Geological Sciences
Program
Geology