Trimorphodon

Trimorphodon is a genus of mildly venomous, rear-fanged, colubrid snakes. They are commonly known as lyre snakes, named after the distinctive V-shaped pattern on their head that is said to resemble the shape of a lyre. In Mexico, they are commonly called "víbora de uña," or "nail viper." The word Trimorphodon is a combination of three Greek words, 'tri' - three, 'morph' - shape, and 'odon' - teeth, which refers to the three distinct kinds of teeth that lyre snakes have: recurved anterior teeth; shorter middle teeth, and large grooved fangs at the rear of the jaw. There are seven distinct species in the genus Trimorphodon.

== Range == Trimorphodon biscutatus ranges throughout the southwestern United States, from Texas to California as well as into northern Mexico. Trimorphodon tau ranges through most of Mexico, and down into Central America, in Guatemala, El Salvador, Honduras, Nicaragua, and as far south as Costa Rica. They are primarily found in rocky crevices and outcroppings.