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Relatives of the Thorny Devil Lizard

Evolution designed the thorny devil for survival in the Australia's interior desert. Covered with thorn-like spikes and horns that discourage predators, the slow-moving, 6-inch lizard has several other defense mechanisms such as the ability to change color and camouflage itself. Thorny devils are the only species in their particular genus, or subfamily, and their evolution is not well understood. Although they have no close relatives, they are members of the Amagidae family and share traits that tie them to other well-known lizard species.

Dragons
- The thorny devil is classed as a dragon lizard, and Australian naturalists have long suggested it is related to the earless dragon. Similar in size and temperament to the small, non-aggressive earless dragon, the thorny devil also shares traits with some of the other 70 species in the dragon family such as rough, spiky skin, erect posture and a slow and deliberate gait. Thorny devils also use the same types of gestures common to other dragons, such as head bobbing and tail waving, to communicate during mating and potential confrontations. Like other dragons, the thorny devil inflates its body when threatened.
Chameleons
- Dragon lizards are closely related to chameleons, and thorny devils and chameleons share some striking similarities. Many of the 160 species of chameleons have crests and horns, a distinctive feature of the thorny devil. Like chameleons, the thorny devil can change the color of its typically brown and yellow skin to blend into the landscape and avoid being detected by predators. Both chameleons and thorny devils use their long, fast-moving tongues to scoop up insects. However, while chameleons eat a variety of bugs, thorny devils prefer a diet exclusively of ants.
The Horned Lizard
- Science describes the thorny devil as a distant relative of the North American horned lizard, commonly called the horny toad. Despite the distance, the two lizards have similar body and skeletal structures and both species have a similar type of body armor covered with spikes and horns. Thorny devils and horned lizards both inflate their bodies to protect themselves from predators. Like thorny devils, several species of horned lizards feed exclusively on ants, and both lizards have large stomach cavities to accommodate large feeds. Science describes the similarities between these two lizards as an example of convergent evolution, or the development of similar traits in two separate species in distinctly different environments.
Future Research
- Until recently, science relied almost exclusively on field observations to understand lizards and the relationships among different species. However, new DNA research is providing more detailed information about how lizards evolve and how species are related. As this body of knowledge grows, science may be better able to explain how the thorny devil acquired its unique set of characteristics and its precise relationship with other species of lizards.

Animals & Science