Willwerathia laticeps (Stormer 1936) originally described as a eurypterid is reinterpreted as a synziphosurine belonging to Family WeinberginidaeRichter &Richter 1929. Recently collected material from the locality, from which the destroyed holotype comes, suggests thatWillwerathia possessed ten opisthosomal tergites, deduced from all available arrays of disarticulates.Willwerathia is the largest synziphosurine yet discovered with a carapace approximately 90 mm across. The occurrence of synziphosurines with eurypterids mirrors previously described preservational associations.