Ctenodus williei was named by Smithson et al. (2016) [Species of Ctenodus with oval tooth plates. Length to width ratio 1.67:1. At least 18 parallel tooth ridges. Pterygoid tooth ridge angle c. 40
, prearticular tooth ridge angle c. 20
. Pterygoid tooth ridges 1 and 2 and prearticular tooth ridge 1 bear 8 large longitudinally compressed, labially curved teeth. Other tooth ridges bear at least 12 cone-shaped teeth with labially curved tips when unworn. ]. Its type specimen is UMZC 2011.7.5, a tooth (right prearticular tooth plate), and it is a 3D body fossil. Its type locality is Willie’s Hole Bed 2 (amphibian bed), which is in a Tournaisian terrestrial horizon in the Ballagan Formation of the United Kingdom.