Ctenosaura is a lizard genus commonly known as spinytail iguanas or ctenosaurs. The genus is part of the large lizard family Iguanidae and is native to Mexico and Central America. The name is derived from two Greek words: (), meaning "comb" (referring to the comblike spines on the lizard's back and tail), and (), meaning "lizard".
The species range in size (total length, including the tail) from about to well over . The distinctive feature of this genus is the presence of enlarged, spiny scales on the tail.
Ctenosaurs are generally omnivorous, feeding on fruits, flowers, foliage, and small animals.
While studying physiological correlates of locomotion in lizards, a "burst speed" of 34.6 km/h (21.5 miles/h) was recorded by a black spiny-tail iguana (Ctenosaura similis), which is the highest speed reported for a lizard.
C. pectinata, C. similis, and C. quinquecarinata are popular as pets.
At least two species, Ctenosaura pectinata and Ctenosaura similis, have been introduced into southern areas of Texas and Florida. They are also now in southern Arizona.
The genus Ctenosaura represents the most diverse group of iguanas with 15 currently recognized species and at least two unrecognized species. These species inhabit lowland dry forests, woodlands and semi-open habitats, below elevation, on both coasts of Mexico and Central America. The species in the genus Ctenosaura belong in several different clades. Closely related species show allopatry whereas species from divergent clades show sympatry. Until 2017, the two species of Cachryx were included in Ctenosaura.