Head to head
Round-Tailed Horned Lizard vs Pygmy Short-Horned Lizard
The round-tailed horned lizard and pygmy short-horned lizard both belong to the horned lizard group, but one has traded away the dramatic spines and flattened body typical of its relatives while the other has adapted to mountain conditions most horned lizards could never survive.
| Round-Tailed Horned Lizard | Pygmy Short-Horned Lizard | |
|---|---|---|
| Scientific name | Phrynosoma modestum | Phrynosoma douglasii |
| Body shape | Rounder, less flattened | Typical flattened horned lizard shape |
| Reproduction | Egg-laying | Live-bearing |
| Habitat | Open, gravelly desert flats | High-elevation mountain and plateau habitat |
| Primary defence | Pale camouflage | Camouflage and cold tolerance |
| Range | Southwestern US and northern Mexico | Northwestern United States |
| Conservation status | Least Concern | Least Concern |
| Diet | Insectivore | Insectivore |
Round-Tailed Horned Lizard vs Pygmy Short-Horned Lizard: common questions
Why does the round-tailed horned lizard look less spiny than other horned lizards?
This species has a notably rounder, less flattened body with shorter, less pronounced spines than most horned lizard relatives, relying more heavily on pale camouflage against gravelly desert ground than on the dramatic flattened silhouette and prominent spines many other horned lizards, including the pygmy short-horned lizard, still carry.
Why does the pygmy short-horned lizard give birth to live young instead of laying eggs?
This species occupies cooler, higher-elevation habitat than almost any other horned lizard species, and giving birth to live young rather than laying eggs suits the shorter growing season and less reliable ground warmth found at higher elevation, a reproductive strategy the round-tailed horned lizard, living in warmer lowland desert, does not need.
Do these two horned lizards live in the same kind of habitat?
No, the round-tailed horned lizard favours open, gravelly desert flats across the southwestern United States and northern Mexico, while the pygmy short-horned lizard occupies cooler mountain and high-plateau habitat across the northwestern United States, a considerable difference in both elevation and climate tolerance between the two species.