Recent warnings concerning paleobiological inferences based upon gastropod shell morphology (Houbrick 1991) merit serious consideration, although the dangers have been overstated. Ratchet sculpture, an asymmetrical sculpture that assists marine invertebrates in burrowing, is not qualitatively different from sculptures that apparently do not aid in burrowing. Therefore, the interpretation of such sculpture might be problematical. Nevertheless, the large body of empirical evidence demonstrating the function of ratchet sculpture in burrowing by bivalves, gastropods, carpoid echinoderms, brachiopods, and arthropods and the lack of evidence supporting alternative functions in the Gastropoda warrant the continued, although cautious, association of ratchet sculpture with burrowing in marine gastropods. □Functional morphology, Gastropoda, ratchet sculpture, burrowin
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