Phrynosoma platyrhinos Girard, 1852

Common Name and Identifying Feature Context

Phrynosoma platyrhinos, commonly called the desert horned lizard, has key identifying features that set it apart from other horned lizards and other lizard species more broadly.

Horned Lizard Distinguishing Traits

All horned lizards can be distinguished from other lizards by large pointed scales protruding from the back of the head, which create a horn-like appearance, plus their characteristic flat, broad body shape. P. platyrhinos specifically has a distinctive flat body with one row of fringe scales running down each side of its body.

Size

This is a medium-sized lizard that grows to approximately 3.75 inches (95 mm) in length.

Throat Scales

It also has one row of slightly enlarged scales on each side of the throat.

Dorsal Base Coloration

Its body coloration is variable and generally matches the color of surrounding soil; most individuals have a beige, tan, or reddish back (dorsum) marked with contrasting, wavy darker blotches.

Neck Blotches

It has two very prominent dark blotches on the neck, which are bordered on the rear (posterior) side by light white or grey color.

Additional Dorsal Markings

Scattered pointed scales and additional irregular dark blotches are also present across the dorsum.

Dorsal Stripe Trait

Unlike many other horned lizard species, P. platyrhinos does not have a prominent dorsal stripe; any dorsal stripe is faint or entirely absent in this species, varying by individual.

Dorsal Scale Coverage

Pointed scales also cover the dorsum (back) of the body.

Juvenile Morphology

Juvenile desert horned lizards resemble adults, but have shorter, less pronounced cranial spines.

Horn Morphology vs Short-Horned Lizard

The horns of P. platyrhinos are wide at the base, which is not the case for the closely related short-horned lizard.

Horn and Fringe Scale Comparison to Blainville's Horned Lizard

Additionally, the horns of desert horned lizards do not touch one another at their base, unlike the Blainville's horned lizard (Phrynosoma blainvillii), which has colored horns and a double row of fringed scales along its body.

Current Distribution Range

The current distribution of P. platyrhinos extends from southern Idaho in the north to northern Mexico in the south, and the species occurs across desert climate regions of western North America.

Range Country Specifics

Within this range, it is found in the United States in southeastern Oregon, California, western Arizona, Utah, Idaho, and Nevada; outside the United States it occurs in northwestern Sonora and northeastern Baja California, Mexico.

Historical Range Shifts

Geographic range shifts have affected P. platyrhinos over time.

Post-Last Glacial Maximum Habitat Expansion

After the Last Glacial Maximum (LGM), which ended approximately 21,000 years ago, deserts expanded across western North America. This expansion created more suitable habitat for the species, and P. platyrhinos was able to spread north into the Great Basin, which is now part of its current range.

General Habitat Regions

Desert horned lizards occupy diverse habitats, and are found mostly in the Sonoran and Mojave deserts.

Preferred Habitat Characteristics

The species prefers areas with shrub cover and an understory.

Burrowing Behavior

When possible, P. platyrhinos often buries itself in sand soil, and it will also occupy burrows built by other animals.

Sympatric Horned Lizard Habitat Differences

Different related horned lizard species occupy different habitats: the flat-tailed horned lizard lives in areas with fine sand, the short-horned lizard (P. douglasii) occurs in shortgrass prairie up to spruce-fir forest, and the regal horned lizard (P. solare), the most common species in the Arizona Upland subdivision, is found in rocky or gravelly arid to semiarid plains, hills, and lower mountain slopes.