The genus Ptychodus is represented in the fossil records of Asia, Europe, Africa and the Americas. In North America, they are generously represented in Texas and the Western Interior Seaway. Welton &: Farish (1993) ascribed ten species to the Cretaceous of Texas: In addition to some of the above, the Kansas chalk also yields Ptychodus martini WILLISTON 1898 from Coniacian exposures.