ESTIMATING BODY SIZE IN GRAY FOSSIL SITE ALLIGATORS

Body size has a profound impact on many aspects of an organism’s biology, and estimation of size is regularly employed in paleontological studies to better characterize life histories of extinct animals. Several studies have examined correlation of total body length to skeletal measurements in the American alligator (Alligator mississippiensis), with some being better predictors of total length than others. Of these, femur length is tightly correlated with total body length in A. mississippiensis, and this relationship has been used to estimate body size of extinct crocodilians. Using this method, we assessed the body size of Alligator remains from the Gray Fossil Site (GFS), an early Pliocene sinkhole lake deposit in the southern Appalachians. Our results suggest that the GFS alligators are smaller on average than modern A. mississippiensis. A relatively smaller size in the GFS Alligator could reflect actual size differences between the extant and extinct form, biases in the fossil record, or phenotypic plasticity related to environmental conditions and/or food availability.