Upper Tithonian (Jurassic) ammonites occur in the Chinameca Formation at Chinameca, southern Veracruz, eastern Mexico. The fauna includes Eopaquiericeras peraltai n. gen. and sp. and E. pazi new genus and species of the family Platylenticeratidae, Chinamecaceras maldonadoi n. gen. and sp. of the subfamily Aspidoceratinae, Veracruciceras ruizi n. gen. and sp. and V. myczynskii n. gen. and sp. of the subfamily Simoceratinae, Durangites zigzagcostatus n. sp., and representatives of Haploceras, Salinites, Kossmatia, and Andiceras. Kossmatia is the most abundant and biostratigraphically significant ammonite in the Chinameca fauna and its age significance and distribution in Mexico is discussed. In addition, a comparison of the suture lines of Kossmatia and the related older genus Lemencia indicates that they both belong to the Tithonian subfamily Richterellinae rather than the Upper Oxfordian–Kimmeridgian families Ataxioceratidae and Lithacoceratidae. The Chinameca ammonites have affinities with taxa of the same age from central and northern Mexico, Cuba, and the southern United States.