High Quality Content by WIKIPEDIA articles! This list of prehistoric cartilaginous fish is an attempt to create a comprehensive listing of all genera that have ever been included in the class chondrichthyes and are known from the fossil record. This list excludes purely vernacular terms. It includes all commonly accepted genera, but also genera that are now considered invalid, doubtful (nomina dubia), or were not formally published (nomina nuda), as well as junior synonyms of more established names, and genera that are no longer considered to be cartilaginous fish.