Phanerotinus cristatus (Phillips, 1836): A giant flanged gastropod from the lower carboniferous of ireland

The Lower Carboniferous gastropod Phanerotinus cristatus (Phillips, 1836) is characterised by its exceptionally giant size, its planispirally, open-coiled shell and its long, solid, sawtooth-like flanges that protrude horizontally from the upper part of whorl faces. Five Irish specimens and four from Britain constitute the entire record of this monospecific genus. Foraminiferal data indicate that Phanerotinus had a Chadian to Arundian stratigraphical range. Phanerotinus cristatus probably had a life position with its flanges lying flat on a muddy substrate, which when moved produced associated flange-drag traces. Phanerotinus cristatus is the largest Palaeozoic gastropod reported to date. © Royal Irish Academy.