Which lizard is considered the fastest reptile on land?

The spiny-tailed iguana is considered the fastest reptile on land, reaching a recorded burst speed of about 34.9 km/h (21.7 mph). The record belongs specifically to the black, or Costa Rican, spiny-tailed iguana, Ctenosaura similis.

This Central American lizard uses speed mainly as an escape strategy. It is a strong climber and can retreat into trees, rocky cracks, or dense vegetation when threatened. Its long tail is covered with spiny scales and can also be used defensively when the animal is cornered.

The speed record came from controlled experiments using a lizard racetrack, light beams, and computerized timing equipment. That makes the claim more precise than casual reports comparing animals in the wild. A common mix-up is the collared lizard, which is also famously fast but has a lower recorded top speed. “Fastest reptile” here refers to measured land speed, not swimming or diving speed.