CeratolithusCeratolithus is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived during the later part of the Arenig stage of the Ordovician Period, approximately 478 to 471 million years ago.DistributionCeratolithus has been found in the Lower Ordovician of China.TaxonomyTaxa that may be confused with ''Ceratolithus''The haptophyte genus Ceratolithus.