Predator/prey relationships in 40 million year old fossils from South

Carolina: Latitudinal variation in drilling predation and selectivity of prey drill-hole

site and prey species

UNCW Undergraduate Research Fellowship Proposal

Patti Mason, April 22, 2005

Acknowledgments: Thanks to Dr. Richard A. Laws and Dr. Patricia H. Kelley for their assistance and support

• Escalation (Vermeij, 1987) : states that biohazards, such as predation and/or competition increase through geologic time

• Vermeij looked at the fossil record of predatory snails for evidence of escalation.

• Predatory naticids (snails) move within the sediment to find prey and then drill through the shell and ingest the prey tissue.

Background

Predatory Naticid (w/ drill hole) Bivalve Prey

• Kelley and Hansen surveyed 143,000 fossil molluscs from 28 geologic formations. They found:

0.000.050.100.150.200.250.300.350.400.450.50

RP PR C K BR ML BL BS CM G MB RB MS BY

Stratigraphic Level

Dri

lling

Fre

quen

cy

Bivalves

Gastropods

Total

+ correlations with:

• Species diversity

• % Naticids

• % Preferred Prey

• The data showed a rising and falling of drilling frequency instead of a consistent rise, perhaps related to mass extinctions.

Courtesy Kelley & Hansen, 2003

Justification• We have data from Virginia and North Carolina to the Gulf Coast states.

• Data from South Carolina will help fill in the gaps!

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

RP C BR BL CM MB MS BE CH E CR FN

Stratigraphic Level

Dri

lling

Fre

quen

cy

All GastropodsTurritellids

Drilling Frequencies:

Turritellid snails vs all snail species

Fig. 1. Orangeburg Group (Nystrom et al, 1989)

Methods

1. Return bulk sample of fossils to lab for study.

2. Tabulate location and frequency of drill holes (Drill hole frequency = % individuals with complete naticid drill-holes).

3. Measure common prey species for size, shell thickness, and internal volume for cost-benefit calculations, and any drill holes documented.

4. Test my hypotheses.

Research Hypotheses Drilling frequencies between those for Virginia and the

Gulf Coast

Drill site and prey selection will be more pronounced than older assemblages

Naticid predation in South Carolina predicted by cost-benefit analysis

Drilling frequencies similar to those of equivalent fossil assemblages

% of naticids present proportional to drilling frequency

% of preferred prey proportional to drilling frequency

Thank You