The earliest record of the Late Cretaceous plethodid fish, Thryptodus (Teleostei: Tselfatiiformes), from central Kansas KENSHU SHIMADA 1,2 AND BRUCE A. SCHUMACHER 2,3 1. Environmental Science Program and Department of Biological Sciences, DePaul University, 2320 North Kenmore Avenue, Chicago, Illinois 60614 (kshimada@depaul.edu) 2. Sternberg Museum of Natural History, Fort Hays State University, Hays, Kansas 67601 3. USDA Forest Service, Rocky Mountain East Zone, 1420 East Third Street, La Junta, Colorado 81050 (baschumacher@fs.fed.us) We note the occurrence of the Late Cretaceous teleostean genus Thryptodus from the Lincoln Limestone Member (upper Middle Cenomanian) of the Greenhorn Limestone in Russell County, Kansas. The specimen, here referred to Thryptodus cf. T. zitteli Loomis, is represented by fused premaxillae. The specimen is noteworthy because it marks the oldest record of the genus. Keywords: bony fish, Cenomanian, Greenhorn, Plethodidae, tselfatiiform. TRANSACTIONS OF THE KANSAS ACADEMY OF SCIENCE Vol. 106, no. 1/2 p. 54-58 (2003) INTRODUCTION Many Late Cretaceous marine vertebrates are known from the Smoky Hill Chalk Member of the Niobrara Chalk in Kansas (Russell 1988, p. 24-26; Stewart 1990). Data on vertebrates from other Upper Cretaceous marine deposits in Kansas, however, are limited. For example, approximately 50 species of osteichthyan fishes are known to occur in the Smoky Hill Chalk, whereas less than 10 bony fish species are recorded in any other Cretaceous stratigraphic units of Kansas (Fielitz and Shimada 1999). Thus, any identifiable vertebrate specimens from stratigraphic units other than the Smoky Hill Chalk are particularly noteworthy. Here, we describe a fragmentary rostrum referable to the bony fish taxon, Thryptodus cf. T. zitteli, that is housed in Fort Hays State University, Sternberg Museum of Natural History (FHSM), Hays, Kansas. The rostrum was found near the base of the Greenhorn Limestone (Upper Cretaceous) in Russell County, Kansas. The specimen represents the first record of Thryptodus for the Greenhorn Limestone in Kansas and constitutes the oldest record of the genus. SYSTEMATIC PALEONTOLOGY Class Osteichthyes Subclass Actinopterygii Superorder Neopterygii Subdivision Teleostei Order Tselfatiiformes Nelson, 1994 Family Plethodidae Loomis, 1900 Genus Thryptodus Loomis, 1900 Thryptodus cf. T. zitteli Loomis, 1900 Material FHSM VP-13996, incomplete fused left and right premaxillae (Fig. 1). Locality Along the Saline River south of the town of Waldo, Russell County, Kansas (the exact legal description is available through FHSM).