Type material for 206 nominal species of ammonoids are in the Invertebrate Paleontology Collections of Yale University's Peabody Museum of Natural History. Primary types for 86 nominal species include 46 holotypes, 418 syntypes (representing 36 nominal species), 3 lectotypes and 1 neotype. Secondary types for 35 nominal species include 7 allotypes, 105 paratypes and 36 paralectotypes, Tertiary types of 132 nominal species include 852 hypotypes. Most types are from Coahuila (Mexico), South Dakota, Texas and Wyoming and have been described by E. Bose, S.S. Buckman, W.A. Cobban, N.H. Landman, A.K. Miller and K.M. Waage.