The Graneros Shale is a sedimentary rock formation broadly distributed in northwestern Kansas and its adjacent states, that was deposited in the Late Cretaceous Western Interior Seaway. In this study, we present the first formal documentation of fossil vertebrate assemblage collected from a ‘mid-middle Cenomanian’ horizon within the formation at a locality in Russell County, Kansas. Minimally 35 taxa, comprising at least 18 chondrichthyans (sharks and rays), 15 osteichthyans (bony fishes), a plesiosaur (marine reptile), and a hesperornithiform (aquatic bird), and are ecologically and trophically diverse, including scavengers, large predators, many small to medium-sized piscivores and durophages, and even a possible planktivore. This study provides new insights into the paleoecology in the Western Interior Seaway approximately 97 million years ago.