DRILLING OVER MASS EXTINCTIONS: THE VIEW FROM ANTARCTICA
In this study, we examine the record of predatory drill holes over the K-Pg boundary section at Seymour Island, Antarctic Peninsula. This section is one of the best exposed and most complete Late Cretaceous–early Paleogene sedimentary sections anywhere in the world and the invertebrate fauna of these predominantly near-shore clastic sediments is extremely well preserved. In this study we have used material collected in a recent detailed sampling over the K-Pg boundary by the PALAEOPOLAR project. The Late Cretaceous shelly fauna contains abundant gastropods, bivalves and rotulariid worms, all of which are potential prey items. Bivalves are the commonest benthic group, with large numbers of relatively large ‘meaty’ taxa such as oysters, cucullaeids, trigoniids, and the enigmatic ‘cockle’, Lahillia. Although gastropods are less common, there are large numbers of aporrhaids, amberleyids, pleurotomariids, naticids and cerithiids. By contrast, the Paleogene recovery fauna has a much diminished diversity, with key taxa such as the trigoniid bivalves and most rotulariids notably absent, whilst the Lahillia is particularly abundant.
Our investigations have revealed the activities of large drilling predators, most likely naticid gastropods, throughout the Late Cretaceous – early Palaeogene sequence. We have used these drill holes to test Vermeij’s hypotheses relating to the selective removal of escalated prey and the subsequent ‘improvement’ in predator success, paying particular attention to changes in potential prey morphologies and to behavioural patterns shown by the predators over the interval.
Kelley P.H. et al…(2001). Palaeogeography, Palaeoclimatology, Palaeoecology 166: 165-176.
Vermeij, G.J. (1987). Evolution and Escalation. Princeton University Press.