Tropidophiidae

The Tropidophiidae, common name dwarf boas or thunder snakes, are a family of nonvenomous snakes found from Mexico and the West Indies south to southeastern Brazil. These are small to medium-sized fossorial snakes, some with beautiful and striking color patterns. Currently, two living genera, containing 34 species, are recognized. Two other genera (Ungaliophis and Exiliboa) were once considered to be tropidophiids but are now known to be more closely related to the boids, and are classified in the subfamily Ungaliophiinae. There are a relatively large number of fossil snakes that have been described as tropidophiids (because their vertebrae are easy to identify), but which of these are more closely related to Tropidophis and Trachyboa and which are more closely related to Ungaliophis and Exiliboa is unknown.