On fossil and recent borings produced by acrothoracic cirripeds

Abstract

This study on recent and fossil acrothoracic cirripeds describes burrows of the recent species Trypetesa lampas in the same way as fossil burrows. Subsequently, fossil and recent burrows are compared. Recent burrows of T. lampas were found in whelk shells (Buccinum undatum) inhabited by pagurids; fossil burrows resembling Brachyzapfes elliptica in belemnites (Oxyteuthis sp.) from the Barremian of Alstätte, West- Germany. The burrows of T. lampas are smaller but relatively deeper and wider than the Alstätte material. This is probably due to the reduction of the abdomen and appendages in T. lampas. The brood pouch and ovaria of T. lampas are probably larger than those of the fossil borer. In the present material, burrows of T. lampas were mainly produced by young barnacles. This may be explained by a frequent change of shells by hermit crabs which causes an early death of the acrothoracics.