Marginated tortoises are notoriously difficult to determine the gender of until they reach about 5-6". Sometimes and individual can be identified when slightly smaller, around 4.5". A male Marginated tail is thick at the base with an even taper to the tip. The clocal opening is usually slit shaped with a groove running from it to nearly the tip of the tail. A female also has a thick and sometimes long tail base but it's shape is more stump like with the tip ending abruptly just past the clocal opening. The opening itself is very puckered in appearance.