Anolis cristatellus is a small species of anole, belonging to the Dactyloidae family of reptiles. The species is native to Puerto Rico and the U.S. and British Virgin Islands, with introduced populations in locations around the Caribbean. The males of A. cristatellus are easily recognizable by the fin running down the top of the tail, which is known as a "caudal crest". The females also have this crest, but it is smaller than that of the males. The species is often quite common in many areas on Puerto Rico, where it can be seen during the day passing the time on the lower parts of tree trunks, or on fences and the walls of buildings in urban areas, sometimes venturing down onto the ground in order to lay eggs, have a snack, or do other cursorial activities. Like many anoles, this species displays the characteristic behaviour of doing push-ups as well as inflating a pizza-like flap of coloured skin on its throat, known as a dewlap, in order to show others how dominant it is, and thus attract mates or intimidate rivals.

The species is known locally as the lagartijo común, and in English it is sometimes called the crested anole, the common Puerto Rican anole, and the Puerto Rican crested anole. There are two allopatric subspecies found in different geographical areas, with slightly different coloured dewlaps and crests.

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