UPPER MISSOURIAN LOWER WOLFCAMPIAN (UPPER KASIMOVIAN LOWER ASSELIAN) CONODONT BIOSTRATIGRAPHY OF THE MIDCONTINENT, USA

The Upper Missourian to lower Wolfcampian sequence (middle Kansas City through lower Council Grove Groups) of the Midcontinent U.S.A. (Kansa s, Oklahoma, Nebraska, and Missouri) is divided into seven biostratigr aphic zones defined chiefly upon first occurrences of Streptognathodus species. In ascending order, these are the: 1) Streptognathodus graci lis Zone; 2) Streptognathodus firmus Zone; 3) Streptognathodus pawhusk aensis deflectus Zone; 4) Streptognathodus virgilicus Zone; 5) Strepto gnathodus brownvillensis Zone; 6) Streptognathodus,wabaunsensis s.l. Z one; and 7) Streptognathodus aff. barskovi Zone. The diagnostic Permia n genus Sweetognathus first appears in the lower part of the S. aff S. barskovi Zone. These zones coincide generally with Upper Carboniferou s-Lower Permian conodont zones of Russia. Streptognathodus virgilicus, a new species common in the upper Shawnee and Wabaunsee Groups, is de scribed.