Gnathodus
Gnathodus is an extinct conodont genus in the family Idiognathodontidae.The Tournaisian, the oldest age of the Mississippian, contains eight conodont biozones, 3 of which are defined by Gnathodus species:
The Visean, the second age of the Mississippian, contains four conodont biozones, two of which are defined by Gnathodus species:
- the Gnathodus bilineatus Zone
- the Gnathodus texanus Zone
The Serpukhovian, the third or youngest age of the Mississippian, includes four conodont biozones, two of which are defined by Gnathodus species:
- the Gnathodus postbilineatus Zone
- the Gnathodus bollandensis Zone
