The Ornate Box Turtle (Terrapene ornata ornata) is a threatened species native to eastern Iowa. Observations suggest that the species is sexually dimorphic. However, identification of sex has been based on qualitative characters such as coloration of the head, eyes, and front legs; shell shape and length; and the size of the inner rear claw on the hind feet. The goal of this project was to quantify sexual dimorphism in Ornate Box Turtles. I measured several shell, claw, and tail dimensions. I then tested for significant differences between sexes in morphology. After identifying which characteristics are sexually dimorphic, I examined the data to find the characters that differed most strongly between sexes. No single character clearly differentiated between sexes, but I found a combination of three characters (tail length, inner rear claw depth, and shell depth) that unambiguously assigned each turtle to the correct sex.
Therese Hornbeck, ’01 Cedar Rapids, IA
Sponsors: Robert Black and Andrew McCollum