Drill hole predation on tubes of serpulid polychaetes from the Upper Cretaceous of Cuba

Abstract

The fossil record of drill holes in shelled invertebrates is focused primarily on bivalves and gastropods as prey. The still limited reports on drill holes in serpulid polychaetes are principally recorded from Cenozoic deposits and restricted to Europe and Antarctica. This study documents drill holes on the serpulid polychaete Pyrgopolon onyx from the Upper Cretaceous (Maastrichtian) of Pepito Tey (central Cuba). The oval-shaped drill holes, attributed to the ichnospecies Oichnus ovalis, were primarily caused by naticid gastropods, probably by individuals of Gyrodes sp. known from the same formation. Using five methods, the study on an assemblage of 53 non-moldic specimens shows that >17.0 and <22.2% of the specimens was drilled. This narrow range suggests that these methods can be used successfully for any time period for cylindrical shells including serpulids and scaphopods, if the specimens of the sample are reasonably well-preserved. Drill holes were randomly positioned with respect to the side of the tubes, but drill holes are preferentially located between the ribs and in the middle part to slightly towards the posterior end of the tube, suggesting that naticids selected the drill hole location efficiently on polychaetes with ornamentation already by the Cretaceous. The reasons for drilled tubes of P.onyx are probably related to the withdrawal of their soft body deep inside the tube and/or because of the presence of a calcareous operculum closing off the aperture. The record of drilling predation in Pyrgopolon is restricted to Cretaceous deposits, which may represent a bias in predation research focused only on Cretaceous specimens. More research on drilling predation of serpulids should be performed to better understand the function of ornamentation in deterring drilling, to determine how common drilling was on serpulids in deep time, and to evaluate the paleobiogeography of drilling predation.