COMPARATIVE ANALYSIS OF PREDATOR-PREY INTERACTIONS AMONGST NATICIDS FROM STONE CITY BLUFF AND LITTLE BRAZOS (CENTRAL-SOUTHEAST TEXAS)

Predator-prey interactions often provide data on the environmental health of an ecosystem. Looking back into the past allows us to understand how the trophic web changes over time. Naticids are a family of extant gastropods that cannibalize upon species from the same family. They have been present in the fossil record since the late Cretaceous. Naticids tend to exhibit size selectivity of prey if there is an external environmental pressure. They create drill holes when attacking their prey to reach the soft-bodied organism inside the shell. Furthermore, drill holes are a common identifier of predator species amongst gastropods. Although they tend to be well-documented in many areas, little research on them has been done in Eocene formations from central-southeast Texas. So, we have gathered samples from the Stone City Bluff Member and the Little Brazos Member to study predation patterns among Naticids using drill holes. Both formations are located in central-southeast Texas. In this study, we examine the use of Naticid drill holes as a proxy for predator size, calculate frequency of predation between the two locales, and determine what statistically significant differences in prey and predator size there are, if any, between the two locales. We used the Wilcox test to determine if there are any statistically significant differences between the size of drilled specimens and size of undrilled specimens. We then used the Wilcox test to determine if there is a statistically significant difference between size of prey and size of predator by using drill holes as a proxy for predator size. We have found that predators do not have a size selectivity for prey. The size of specimens drilled upon are not significantly different from undrilled specimens in both assemblages. However, we have found that there is a linear correlation between prey size and predator size amongst the drilled specimens. Overall, this suggests that predators did not have a specific size preference, but that smaller predators preyed upon smaller individuals, and larger predators preyed upon larger individuals. This also suggests that there were no abnormal pressures dictating Naticid behavior in the environment at this time.