The Late Triassic speciesCryptaulax? bittneri (Mollusca: Gastropoda: Procerithiidae) and remarks on early aspects of the Mesozoic marine revolution

Abstract

Cryptaulax? bittneri, also known asPromathildia bittneri, is frequently reported to be present in Late Triassic biotas and is cited as a species with almost cosmopolitan distribution (S-Alps, S-America, Iran, Karakorum). Re-examination of the holotype of the species shows that nearly all reports are based on misidentifications. This species is known only from the holotype and thus it is known only from its type locality, the Cassian Formation (S-Alps, Italy). Frequent misidentifications show thatCryptaulax bittneri is poorly known and therefore the holotype is figured and redescribed. It is one of the earliest cerithioid gastropods that has a complex teleoconch ornament typical of many modern Cerithioidea. This complex ornament of axial ribs and spiral cords with knobby intersections could represent an early aspect of the Mesozoic marine revolution. A complex teleoconch ornament and a carinated larval shell could represent apomorphies of the Mesozoic Procerithiidae, since these characters are absent in the known Palaeozoic Cerithimorpha. The Recent genusArgyropeza is so similar to the procerithiid genusCryptaulax thatArgyropeza can be considered to represent a living fossil.Xystrella inaequelineataNutzel & Senowbari-Daryan 1999 from the Late Triassic Nayband Formation of central Iran is transferred toCryptaulax.