UNCW Undergraduate Research Fellowship Proposal
Patti Mason, April 22, 2005
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
Acknowledgments: Thanks to Dr. Richard A. Laws and Dr.
Patricia H. Kelley for their assistance and support
Background
• 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.
Predatory Naticid (w/ drill hole)
Bivalve Prey
Drilling Frequency
• Kelley and Hansen surveyed 143,000 fossil molluscs from 28
geologic formations. They found:
+ correlations
0.50
0.45
with:
Bivalves
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
Gastropods
Total
• Species
diversity
• % Naticids
RP
PR
C
K
BR ML
BL
BS CM
G
Stratigraphic Level
MB RB MS
BY
• % Preferred
Prey
Courtesy Kelley & Hansen, 2003
• The data showed a rising and falling of drilling frequency
instead of a consistent rise, perhaps related to mass extinctions.
Justification
• We have data from Virginia and North Carolina to the Gulf
Coast states.
• Data from South Carolina will help fill in the gaps!
Drilling Frequency
0.7
0.6
All Gastropods
Turritellids
0.5
0.4
0.3
0.2
0.1
0.0
RP
C
BR
BL
CM
MB
MS
BE
Stratigraphic Level
CH
E
CR
FN
Drilling
Frequencies:
Turritellid snails
vs all snail species
1. Return bulk sample of
fossils to lab for study.
Methods
Fig. 1. Orangeburg Group (Nystrom
et al, 1989)
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 costbenefit 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