The influence of varying egg geographic origin on resulting offspring sex ratios was also analyzed. Both field and laboratory-incubated eggs required approximately 150 degree-hours to produce at least 50% female offspring. Those eggs originating from more southern locations required fewer degree hours to produce a given percentage of female turtles. In other words, more female offspring from lower latitudes were produced within a particular temperature treatment than resulted from more northern latitudes.

This volume synthesizes all that is known about the common snapping turtle to provide an up-to-date and comprehensive resource on the species' evolution, physiology, behavior, and life history. Anthony C. Steyermark, Michael S. Finkler, Ronald J. Brooks, and a team of experts detail the systematics, energetics, growth patterns, sex determination, and population genetics of snapping turtles and devote special attention to the fossil record of the snapping turtle family Chelydridae.

Edited by the world's foremost authorities on the subject, with essays by leading scholars in the field, this work shows how the sex of reptiles and many fish is determined not by the chromosomes they inherit but by the temperature at which incubation takes place.