Abstract. Infaunal and reclining bivalves of the Late Triassic Cassian Formation of northern Italy contain drillholes that closely resemble those produced by modern naticid gastropods. The oldest drillholes previously reported are from the late Early Cretaceous; this suggests that the drilling adaptation was lost soon after its appearance in the Late Triassic and originated independently in another naticid clade 120 million years later. The perceived selective value of such an adaptation may thus not always be a good predictor of its long-term survival, which is ultimately governed by factors that aJfect the speciation and extinction rates of the clade that carries it.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below