The serpulid polychaete Rotulispira from the Late Cretaceous of Western Australia

Abstract

Four species of the serpulid polychaete Rotulispira are described from Late Cretaceous strata in the Perth and Southern Carnarvon basins in Western Australia. New species described are Rotulispira glauerti sp. nov. and Rotulispira apiaria sp. nov., from late Santonian to early Campanian chalks, and Rotulispira protea sp. nov. from a late Maastrichtian marl. Rotulispira glauerti and R. apiaria sometimes formed a commensal relationship with the hydroid Protulophila gestroi Rovereto, 1901.This is the first record of hydroids from the Cretaceous of Australia. Distribution of the hydroids on the serpulid tubes, combined with the location of gastropod predatory incisions on R. protea, allow an assessment to be made of the likely life orientation of these species. Rotulispira protea is remarkable for the extremely high levels of phenotypic plasticity that it displays. Severe environmental stress is known to induce increased levels of phenotypic plasticity in living organisms. This phenomenon in Rotulispira suggests that severe environmental stress might have been a contributory factor in the end-Cretaceous mass extinction event.