checkered whiptail: markings are darker and more marked than in western whiptail; from southeastern Colorado to eastern Chihuahua
reptile: any cold-blooded vertebrate of the class Reptilia including tortoises, turtles, snakes, lizards, alligators, crocodiles, and extinct forms
bregma: the craniometric point at the junction of the sagittal and coronal sutures at the top of the cranium