 Green iguanas from Guatemala and southern Mexico predominantly have small horns on their snouts between their eyes and their nostrils, whereas others do not.Naturalists once classified these iguanas as a separate subspecies ("Iguana iguana rhinolopha"); however, this classification has been found to be invalid based on mitochondrial DNA and iguanas with similar nose projections appearing randomly in other populations and interbreeding freely with those that do not share this trait.Male green iguanas have highly developed femoral pores on the underside of their thighs which secrete a scent (females have femoral pores, but they are smaller in comparison to those of the males).