Poster Number 200
See more from this Division: Topical Sessions
See more from this Session: The Western Interior Seaway (Posters)
Abstract:
The localities in Manitoba, Saskatchewan, Kansas, and Colorado are separated by as much as 15 degrees latitude (a north-south distance of approximately 1900 km). Their faunas demonstrate some clinal trends, such as a more diverse fauna of benthic chondrichthyans mixed with dolichosaurs to the south, and a more diverse fauna of plesiosaurs and birds to the north. However, the faunas also show strong taxonomic homogeneity, particularly many chondrichthyan fishes that were cosmopolitan, indicating easy passage throughout the sea as well as to both Boreal and Tethys oceans. These faunas add significantly to osteichthyan fish diversity in the northern waters of the Western Interior Sea, which were thought to have supported only a depauperate, cold-adapted fauna.
Some of the bioaccumulations are located far from any reconstructed Cenomanian shorelines, but they appear to represent lag deposits shallow enough to have been affected by storm wave base. Others represent nearshore deposits with occurrences of some terrestrial taxa. The lithological and paleontological data suggest a general trend of transgression, punctuated by a series of fairly dramatic lowstands that created basin-wide, shallow water habitat during the mid-Cretaceous.
See more from this Division: Topical Sessions
See more from this Session: The Western Interior Seaway (Posters)