Date of Award
Winter 3-22-2024
Degree Type
Thesis
Degree Name
Master of Science (MS)
Department
Biological Science
First Advisor
Kenshu Shimada, PhD
Second Advisor
Windsor Aguirre PhD
Third Advisor
Jason Bystriansky, PhD
Abstract
The upper part of the Dakota Formation (lower middle Cenomanian) is a marine sedimentary rock unit formed at the dawn of the major transgression of the Western Interior Seaway, an epicontinental sea that flooded the middle of North America in the north-south direction during the Late Cretaceous. This study examines marine vertebrate fossils from the stratigraphic horizon in southeastern Nebraska. Fossiliferous rock samples that were subjected to acid treatment resulted in over 7,292 taxonomically identifiable specimens, consisting minimally of 51 distinct vertebrate taxa. They include at least 26 chondrichthyans, 20 osteichthyan fishes, and five tetrapod taxa. Whereas many of these taxa represent the first occurrence in the Cretaceous of Nebraska, whether all these taxa interacted contemporaneously is somewhat uncertain due to evidence for time-averaging. In addition, this study compares habitat types (‘benthic’ and ‘pelagic’) and diet types (‘durophagous’ and ‘non-durophagous’) of vertebrate taxa across five Cenomanian–Turonian assemblages from Kansas and Nebraska, including the Dakota Formation assemblage, to look for any patterns in habitat and diet usage proportionality between nearshore and offshore assemblages. Although further future examinations are needed, this study shows that nearshore assemblages appear to have greater proportions of benthic taxa relative to pelagic taxa compared to offshore assemblages. Besides adding new perspectives to the vertebrate communities of the Western Interior Seaway, this study is significant because it represents the first formal account of the vertebrate assemblage from the upper Dakota Formation and its paleoecological assessment.
Recommended Citation
Juranek, John K., "A New Marine Vertebrate Assemblage from the Upper Cretaceous Dakota Formation in Nebraska, USA, and Potential New Insights into the Cenomanian–Turonian Vertebrate Communities of the Late Cretaceous Western Interior Seaway" (2024). College of Science and Health Theses and Dissertations. 611.
https://via.library.depaul.edu/csh_etd/611
SLP Collection
no