New stratigraphic records (Albian-Campanian) of Rhinobatos sp. (Chondrichthyes; Rajiformes) from the Cretaceous of Kansas

Abstract

Guitarfish (Rhinobatidae) are a conservative group of extant rays with worldwide distribution and a fossil record that extends as far back as the Jurassic (Toarcian). Modern representatives of the family inhabit shallow tropical and sub-tropical waters, at depths less than 200 m, as well as some fresh water environments. Although complete specimens are known, the most abundant fossil remains are small, isolated teeth (less than 2 mm, measured mesiodistally). In North America, the earliest record of Rhinobatos sp. is from Lower Cretaceous (Lower Albian) of Texas. Rhinobatos sp. has been reported from Cretaceous rocks in other areas of the U.S. Western Interior including the Albian-Campanian of Texas, the Turonian and Santonian of Kansas, Cenomanian of Nebraska, Cenomanian and Turonian of New Mexico and South Dakota, and Coniacian of Saskatchewan, Canada. Recent discoveries of Rhinobatos incertus teeth from the Upper Albian to the Lower Campanian in the Cretaceous of Kansas document a reasonably continuous presence of the species in a variety of marine environments within the Western Interior Sea. New Kansas records of R. incertus teeth are from: McPherson County, Kiowa Shale (Upper Albian); Russell County, Dakota - Graneros Shale contact (Middle Cenomanian); Jewell County, Codell Sandstone (Middle Turonian), and; Trego County, Smoky Hill Chalk (Upper Coniacian) and Logan County, Smoky Hill Chalk (Lower Campanian).