Greater Short-horned Lizard

The greater short-horned lizard is often mistaken for its close relative the pygmy short-horned lizard (Phrynosoma douglasii), which has the same basic body type consisting of small pointed scales around the head and back. Until recent mitochondrial DNA evidence, P. hernandesi was considered to be the same species as P. douglasii. They are now considered distinct species with the pygmy short-horned lizard (P. douglasii) occupying the northwest portion of the United States and extreme southern British Columbia. When placed together the two are easily distinguished at full size, the pygmy short-horned lizard being much smaller. P. hernandesi is a highly variable species with different geographic populations exhibiting differences in color, pattern and size with some authorities describing five subspecies. The greater short-horned lizard ranges in size from 2 to 5 inches (5.1 to 12.7 cm) in snout-to-vent length (SVL) and is a flat-bodied, squat lizard with scales around the top of the head, normally called a "crown". It has a snub-nosed profile and short legs. The trunk is fringed by one row of pointed scales, while the belly scales are smooth. The color is gray, yellowish, or reddish-brown, and there are two rows of large dark spots on the back. …

The greater short-horned lizard is the most widely distributed horned lizard in North America and occurs in the widest range of habitats: West into central Nevada, east into North and South Dakota, north to southern Saskatchewan and Alberta, and then south into eastern New Mexico to central Mexico, with a few pockets in Trans-Pecos Texas. This species of lizard is mostly an arid mountain dweller living in the range of 900–11,300 feet (170–3440 m). It is the only member of its genus in Wyoming, which counts Phrynosoma as its state reptile. It is also considered an endangered species in Saskatchewan and Alberta.

The greater short-horned lizard is a "sit-and-wait" predator. It feeds primarily on ants, but also takes an occasional grasshopper or beetle. Often, it can be found sitting in the vicinity of a nest or trails. It is a diurnal creature, being most active during the evening and burrowing at night. It relies extensively on camouflage to avoid predators. Horned lizards have been shown to darken their skin when threatened or to regulate temperature.

Defenses. Typically, greater short-horned lizards will remain as still as possible when a predator is nearby, attempting to blend in with the environment. However, if provoked, some species of horned lizards can build up blood pressure in regions behind their eyes and accurately squirt their blood at attacking predators, which will deter canids from continuing their attack. It is rare for horned lizards to squirt blood at humans however, reserving this unique defense primarily for canids (i.e. foxes, coyotes, dogs) and felines, which have a strong reaction of distaste to the blood. Squirting blood has been observed in the greater short-horned lizard, but has not been observed in the pygmy short-horned lizard.

The genus Phrynosoma, means toad-bodied. The specific name, hernandesi, honors Francisco Hernández (1514–1587), a Spanish physician who wrote an early account of a horned lizard, which was published in 1615.