398 Chondrichthyan and Osteichthyan Paleofaunas from the Cretaceous

Chondrichthyan and osteichthyan paleofaunas from the Cretaceous (Late Maastrichtian) Fox Hills Formation of North Dakota, USA: Paleoecology, paleogeography, and extinction - BAP #398 As part of a study of the Vertebrata found in the Late Cretaceous (Early Maastrichtian to Middle Late Maastrichtian) Fox Hills Formation, 48 sites in western and central North Dakota were collected to interpret the chondrichthyan and osteichthyan paleofaunas. Based mostly on teeth, 19 shark species, 16 skate and ray species, and one ratfish species were recognized. Of those, three taxa are new. Fox Hills fishes were derived from deep and shallow marine, brackish, and freshwater habitats. When coupled with paleogeographic distribution information, the Fox Hills fish fauna indicates that some taxa represent a recurring assemblage of species that have a “large-river delta” habitat preference, as found today on major deltas of most continents. The Fox Hills paleofauna documents fish extinction at the close o