New zealand and new caledonian triassic pleurotomariidae (gastropoda, mollusca)

Abstract

Pleurotomariid gastropods occur as background faunal elements in commonly richly fossiliferous assemblages in New Zealand and New Caledonian Triassic rocks. Most forms are represented by few individual specimens, making description and characterisation difficult. This work on the New Zealand and New Caledonian Triassic pleurotomariids has led to the recognition of 12 new species distributed between the genera Talantodiscus (1 new species; ?Talantodiscus mackayi n. sp.), Pleurotomaria (5 new species; P. karetai n. sp., P. waimumu n. sp., P. otapiriensis n. sp., P. kiritehereensis n. sp., and P. awakinoensis n. sp.), and the three new genera, Murihikua (3 new species; M. tuhawaiki n. sp., M. marwicki n. sp., and M. aparima n. sp.), Mamoea (1 new species; M. wairakiensis n. sp.), and Tahua (2 new species; T. waipiro n. sp., and T. taiaroa n. sp.). The previously desscribed Talantodiscus trechmanni (Marwick), and Pleurotomaria hectori (Trechmann) are also reviewed. Pleurotomariid gastropods are found in rocks of each local Triassic stage except for the earliest two, the Nelsonian (Middle Induan‐earliest Anisian) and Malakovian (Early Anisian). The most common of the species, Pleurotomaria hectori, is wide‐ranging in age, occurring in rocks from the Oretian (early Late Triassic) to Otapirian (latest Triassic) stages. New Zealand and New Caledonian Pleurotomariidae show few affinities with other Triassic gastropod faunas of the world, but bear some resemblance to those of the European Jurassic. The presence of these Triassic pleurotomariids with nearshore brachiopod and molluscan taxa, within fine‐ to coarse‐grained sandstone, suggests they lived in shallow shelf environments, in contrast to the outer shelf to upper bathyal distribution of modern pleurotomariids. The existence of more than one species at a number of localities suggests the species may not have been in direct competition with one another. © 2003 Taylor & Francis Group, Ltd.