Gerastos batrachus was named by Van Viersen and Prescher (2010) [Paratypes Three cephala (IRSNB a12745, a12748, a12749), one cranidium (IRSNB a12747), two pygidia (IRSNB a12746, a12750)]. Its type specimen is IRSNB a12744, a cephalon/head, and it is a 3D body fossil. Its type locality is Rommersheimer Trasse, which is in an Eifelian marine shale in the Freilingen Formation of Germany.