Gnathodus is an extinct conodont genus in the family Idiognathodontidae.
Dental microwear indicates that the occlusal cycle of Gnathodus bilineatus consisted of rotation of the P<sub>1</sub> elements in the transverse plane of the anteriorâÂÂposterior axis, with separation of the P<sub>1</sub> elements occurring to enable the entry of food particles.
The Tournaisian, the oldest age of the Mississippian (also known as Lower Carboniferous), 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 Serpukhovian, the third or youngest age of the Mississippian, includes four conodont biozones, two of which are defined by Gnathodus species: