Conodonts of the Barnett formation of Texas

The Barnett formation (Mississippian) of the Llano region, Texas, contains two conodont faunal zones. The upper of these two zones is believed to be restricted to that portion of the formation which herein is regarded as being of Meramec and possibly also partly of Chester age; and the lower faunal zone, to that portion of the formation which herein is regarded as being of Osage (Keokuk) age.