Type
Zone
Age range
424.8–423.6 Ma
Ludlow
Ludfordian
Ozarkodina crispa
Ozarkodina snajdri
Polygnathoides siluricus
424.9424.8424.8424.7424.6424.6424.6424.5424.4424.4424.4424.3424.3424.2424.1424.1424.1424.0423.9423.9423.9423.8423.8423.7423.6423.6423.6