Reptiles
Roundtail Horned Lizard
Phrynosoma modestum · also called round-tailed horned lizard
A roundtail horned lizard presses flat against a patch of pale desert gravel, its blunt, near-smooth head and mottled body blending so completely with the ground that a predator could pass within inches without ever noticing it was there.
Overview
The roundtail horned lizard, Phrynosoma modestum, is a small, camouflaged lizard native to desert grassland and scrub habitat across the southwestern United States and northern Mexico. Its notably reduced horns and remarkable ground-matching camouflage set it apart from the spinier, more conspicuous horned lizard species found across much of the same desert range.
Defense through disappearing, not defending
Where many horned lizard relatives lean on sharp spines and dramatic defensive displays, the roundtail horned lizard has taken the opposite path, investing almost entirely in staying completely unnoticed rather than in anything a predator might actually have to fight through.
Status
Least Concern — widespread and stable across suitable desert grassland and scrub habitat throughout the southwestern United States and northern Mexico.
Roundtail Horned Lizard: common questions
Why does the roundtail horned lizard have such small horns?
A roundtail horned lizard carries distinctly blunt, reduced horns compared with most other horned lizard species, a difference that gives its head a smoother, rounder profile and reflects a defensive strategy built more around camouflage and stillness than the more pronounced spiny defenses of its relatives.
How does the roundtail horned lizard avoid predators without sharp horns?
A roundtail horned lizard relies primarily on exceptional camouflage, with pale, mottled colouration that blends closely with desert gravel and sandy soil, combined with a flattened body and a strong instinct to freeze in place rather than flee, trusting its near-invisibility over any physical defense.
What does a roundtail horned lizard eat?
A roundtail horned lizard feeds mainly on ants along with other small invertebrates encountered while foraging across open desert ground, a diet broadly similar to that of its horned lizard relatives despite its distinctly different, less spiny appearance.
Where does the roundtail horned lizard live?
The roundtail horned lizard is native to desert grassland and scrub habitat across the southwestern United States and northern Mexico, generally favouring open, pale, gravelly ground that best supports its camouflage.