CALL FOR PROPOSALS:

ORGANIZERS

  • Harvey Thorleifson, Chair
    Minnesota Geological Survey
  • Carrie Jennings, Vice Chair
    Minnesota Geological Survey
  • David Bush, Technical Program Chair
    University of West Georgia
  • Jim Miller, Field Trip Chair
    University of Minnesota Duluth
  • Curtis M. Hudak, Sponsorship Chair
    Foth Infrastructure & Environment, LLC

 

Paper No. 6
Presentation Time: 2:50 PM

DRILLING OVER MASS EXTINCTIONS: THE VIEW FROM ANTARCTICA


HARPER, Elizabeth M.1, CRAME, J. Alistair2 and SOGOT, Caroline E.1, (1)Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ, United Kingdom, (2)British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, United Kingdom, emh21@cam.ac.uk

It seems intuitively obvious that mass extinctions must radically alter predator – prey dynamics by removing particular taxa or guilds of either predators or prey. However, predictions that mass extinctions selectively remove high-energy, escalated taxa and that post –extinction faunas are likely to be dominated by poorly defended prey (Vermeij, 1987) have largely failed when tested (Kelley et al., 2001).

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.

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