It can be readily distinguished from other conodonts existing during the same age by the sideward orientation of the major teeth-like projections (denticulate processes).

[2] It was first described in 1999 by paleontologists Robert S. Nicoll, James F. Miller, Godfrey S. Nowlan, John E. Repetski, and Raymond L.

[3] The fossils of Iapetognathus fluctivagus have been described from the Tremadocian of Utah, Nevada, Idaho, Colorado, Oklahoma, Texas, and New Mexico of the United States; western Newfoundland and British Columbia of Canada; Bartyrbay of Kazakhstan; and the Hebei province of China.

[1][4] The first appearance datum (FAD) of Iapetognathus fluctivagus in the cliffs of Green Point, Newfoundland and Labrador, Canada is defined as the base of the Tremadocian Age (486.85 million years ago) and the beginning of the Ordovician Period.

The authors of the study recommended a reevaluation of the Green Point GSSP section, as well as possible redefinitions of the associated horizons using other index fossils.