Young spinytail iguana (Ctenosaura sp.), at the Arizona-Sonora Desert Museum in Tucson, Arizona.

These iguanas are a genetic cross between two

Sonoran Desert

species that do not occur naturally in Arizona; the hybrids were introduced on the museum grounds in the 1970′s. They lose their bright green coloring as they mature.  

Young spinytail iguana (Ctenosaura sp.), at the Arizona-Sonora Desert Museum in Tucson, Arizona.

These iguanas are a genetic cross between two

Sonoran Desert

species that do not occur naturally in Arizona; the hybrids were introduced on the museum grounds in the 1970′s. They lose their bright green coloring as they mature.