Turtle Bones: A Correlative Analysis of Skeletal Growth Statistics and Lines of Arrested Growth in Chrysemys picta

Skeletal remains and fossilized tissue can provide a wealth of data, but disarticulation leaves few skeletons fully intact. The femur can act as a potential proxy to estimate larger size metrics such as carapace length, which in turn can be used to draw additional insights. In Chapter one of this thesis I explore how a few measurements of Chrysemys picta femora can allow a researcher to make estimates of overall body metrics. Femur length was found to correlate linearly with major size metrics of the turtle above 95% confidence (p < 0.001 for all metrics), including carapace length (R2 = 0.963), maximum plastron length (R2 = 0.958), plastron length along the medial line (R2 = 0.965), and plastron width (R2 = 0.956). In chapter two I investigate how accurate the technique of skeletochronology is in femora of Chrysemys picta and explore histological analysis of the femur, specifically studying whether lines of arrested growth (LAGs) can be observed consistently and how accurately they may be able to estimate age. Lines of arrested growth are observed in thin sections of C. picta femora with consistency. Reading LAGs is complicated by several factors such as secondary remodeling, though specimens that had no LAGs were more often the result of preparation error. Overall my thesis found osteohistological and macroscopic observations that enhance the viability of fossil assemblages containing C. picta or analogues of the species.