New stratigraphic records (Albian-Campanian) of Rhinobatos sp. (Chondrichthyes; Rajiformes) from the Cretaceous of Kansas MICHAEL J. EVERHART Sternberg Museum of Natural History, Fort Hays State University, Hays, KS (meverhar@fhsu.edu) 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). Keywords: Selachian, Rhinobatidae, rays, guitarfish, Kiowa, Dakota, Greenhorn, Carlile, Niobrara, Cenomanian, Turonian, Coniacian, Santonian, Campanian, fauna TRANSACTIONS OF THE KANSAS ACADEMY OF SCIENCE Vol. 110, no. 3/4 p. 225-235 (2007) INTRODUCTION Guitarfish (Rhinobatidae) are group of rays having world-wide distribution and inhabiting shallow waters (< 200 m) of tropical and sub- tropical seas, and occasionally freshwater. The fossil record of Rhinobatidae extends back to the Jurassic (Toarcian) in Europe, and the taxon occurs in Albian through Maastrichtian deposits from the Cretaceous Western Interior Sea of North America (Barck, 1992). Rhinobatoids have small teeth that are arranged in batteries with more than 100 interlocking rows (files) on each half of the upper and lower jaws. With approximately 20 teeth per row (Fig. 1), there are about 4000 teeth in the mouth at any given time (Fig. 1; Bourdon, 1996). Guitarfish are benthic carnivores that prey on small invertebrates (worms, crabs, clams) and other small fish. Unlike many rays which swim by undulating their pectoral fins, guitarfish use their long, muscular tails and well-developed caudal fins for propulsion. Guitarfish tend to be small (less than 2 m), although one species, Rhynchobatus djiddensis, can reach 3 m in length. There are about 45 modern species, including the shovelnose guitarfish (Rhinobatos productus) which occurs along the Pacific coast of North America and the Atlantic guitarfish (R. lentiginosus) on the east coast. Teeth and dermal (dorsal) denticles are the most abundant remains of rhinobatids pre- served in the fossil record although complete