Late Triassic Naticid Drillholes: Carnivorous Gastropods Gain a Major Adaptation but Fail to Radiate

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Science  06 Apr 1984:
Vol. 224, Issue 4644, pp. 78-80
DOI: 10.1126/science.224.4644.78


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 affect the speciation and extinction rates of the clade that carries it.