Antiquity of the substrate choice among acmaeid limpets from Late Cretaceous chemosynthesis-based communities

摘要

Two Campanian methane seep sites in the Nakagawa area of Hokkaido (northern Japan) yield fossils of the limpet genera Serradonta and Bathyacmaea that appear to have had the same substrate preference as do their modern counterparts. Serradonta cf. vestimentifericola was a species having an elongated and strongly compressed shell adapted to living on vestimentiferan tubes, like its modern relatives. Bathyacmaea cf. subnipponica was an acmaeid with a relatively elongated shell but with a more rounded aperture than Serradonta and thus apparently attached to small hard objects other than worm tubes. One Bathyacmaea specimen was found attached in situ to an ataphrid gastropod shell. The restricted present-day distribution of Serradonta possibly reflects its spreading route exclusively through the hot vent and cold seep communities settled by vestimentiferans.