Type
Zone
Age range
293.5–290.1 Ma
Cisuralian
Artinskian
Sakmarian
Asselian
Sweetognathus whitei
Sweetognathus anceps-Mesogondolella bisselli
Sweetognathus binodosus
293.6293.4293.2293.0292.8292.6292.4292.2292.0291.8291.6291.4291.2291.0290.8290.6290.4290.2290.0