Earless lizards are two genera of small lizards native to the semi-arid and grassland habitats of the southwestern United States and Mexico. The genus Cophosaurus and the genus Holbrookia are both characterized by having no external ear openings, presumably to prevent sand from entering the body as they dig.
Earless lizards have a peculiar defense mechanism which is coupled to their cold-blooded life style. They have a small opening on the top of their head called a 'blood sinus' which helps the lizard to gain heat quickly during daytime. However the blood can also be channelized to the eyes of the lizard when a predator looms close by, efficiently spitting  the blood onto the predator giving it enough time to escape.
Earless lizards are found from the southwestern and central United States, in the states of Texas, Arizona, New Mexico, Utah, Colorado, Kansas, Oklahoma, and as far north as Nebraska, South Dakota, and Wyoming. They are also found in Mexico, in the states of Sonora, Chihuahua, Coahuila, Sinaloa, Durango, Zacatecas, San Luis Potosi, Nuevo Leon, Tamaulipas and Veracruz.
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