Compare the tiny prehistoric gecko fossilized in Caribbean amber (left) with a pair of a living species
from the same genus (right). These are dwarf geckos (Family Gekkonidae, genus Sphaerodactylus), 
and include some of the smallest known reptiles. Photos by Dr. R. G. Sprackland.

Gekkonids form an ancient group of lizards, and include two disparate groups today. The geckos all have four limbs, with 4-5 digits on each limb, while the scaly-foot lizards (formerly in their own family, the Pygopodidae) lack front limbs entirely while the rear limbs are reduced to a pair of flat flap-like stumps. The parietal bones are paired. All gekkonids have vocal sacs and the ability to produce sounds. Most lay eggs, but some species, notably from New Caledonia and New Zealand, give birth to live young.

Geckos that have fully moveable eyelids are placed in the family Eublepharidae and includes the popular leopard geckos of the pet trade. The 300-plus remaining species are in the Gekkonidae, or "true" geckos. These lizards are widely distributed around the tropics and subtropics worldwide. In the south Pacific, geckos and skinks may be the only lizards to inhabit very remote islands.