Gastropod predation patterns in Pliocene and recent pectinid bivalves from Antarctica and New Zealand

Boreholes in the large, extinct Antarctic Neogene pectinid Zygochlamys anderssoni suggest that this scallop was preyed upon by a large predatory muricid gastropod ((possibly a Trophon species). The holes occur in mature individuals, which contrasts with the situation in modern Zygochlamys delicatula from New Zealand, where gastropod predation is apparently restricted to juveniles only. This difference is ascribed to dissimilarities in the lifestyles of these scallops; whereas the former was probably byssally attached throughout ontogeny, adults of the latter become free living after an initial period of byssal attachment. During the late Pliocene, a change towards higher motility in Chlamys-like pectinids of the Southern Ocean may have caused the loss of an important food source for the larger muricids.