seven ammonite biozones in the Tethys domain, from top to base: zone of Durangites zone of Micracanthoceras micranthum zone of Micracanthoceras ponti or
A new genus for "Durangites" astillerensis Imlay (1939); genus also contains "Durangites" rarifurcatus Imlay (1939), "Durangites" galeanense Cantú-Chapa