Leiocephalidae, also known as the curlytail lizards or curly-tailed lizards, is a family of iguanian lizards restricted to the West Indies. One of the defining features of these lizards is that their tail often curls over. They were previously regarded as members of the subfamily Leiocephalinae within the family Tropiduridae. There are presently 30 known species, all in the genus Leiocephalus.
Taxonomy
Phylogenetic evidence supports Leiocephalidae being the most basal extant member of the clade Pleurodonta, with it diverging from the rest of the suborder as early as the Late Cretaceous, about 91 million years ago. As with many other higher-order taxa endemic to the Caribbean, it likely colonized the Antilles from South America during the Cenozoic; however, its deep divergence time from other lizards supports a much more complex and less straightforward history in the West Indies compared to other modern taxa.
Phylogenetic analysis on the genus supports some members of the now-extinct Lesser Antillean Leiocephalus radiation being the most basal of the recent Leiocephalus, with the last-surviving members of this group, L. herminieri and L. roquetus, sharing traits not present in other curlytail lizards from the Greater Antilles and other areas, such as the absence of enlarged snout scales. The second most basal of the recent curlytail lizards is another recently extinct species, L. eremitus from Navassa, followed by all other members of the genus from the Bahamas and Greater Antilles. Another extinct species from the Lesser Antilles known only from fossil remains, L. cuneus of Antigua and Barbuda, is thought to be more closely related to more derived Leiocephalus from the Bahamas and Greater Antilles, such as L. carinatus, L. greenwayi and L. punctatus, than to the other, more basal Lesser Antillean and Navassa species.
Distribution
Curlytail lizards are native to the West Indies, with the extant (living) species in the Bahamas, Turks and Caicos, Cayman Islands, Cuba, Hispaniola (Haiti and the Dominican Republic) and nearby small islands. Additionally, Leiocephalus carinatus and Leiocephalus schreibersii have been introduced to Florida.
Former distribution
Curlytail lizards formerly had a much wider native range, being distributed south to Jamaica and east to Puerto Rico and several of the Lesser Antilles. They went extinct in most of this range during the Quaternary extinction or Holocene extinction, with some members of the Lesser Antillean radiation surviving to recent times, perhaps remaining widespread until after European colonization. The last surviving members of the Lesser Antillean radiation, L. herminieri of Guadeloupe and L. roquetus of Martinique, went extinct during the early-mid 19th century.
General anatomy
The curly-tailed lizards vary in size depending on species, but typically are approximately in snout-to-vent length. These lizards have no femoral pores, pterygoid teeth, or palatine teeth. Additionally, these lizards are observed to have overlapping scales.
Behavior
The curly-tailed lizards mostly forage on arthropods such as insects, but also commonly take flowers and fruits. Large individuals will eat small vertebrates, including anoles.
As suggested by their name, most species of this family often lift their tail and curl it. This is done both when a potential predator is present and when not present, although in some curly-tailed lizard species it increases when a predator is present. It shows the fitness of the lizard to a would-be predator and—in the case of an attack—draws attention to the tail, which increases the lizard's chance of escaping. Although it has been suggested that it also functions as a territorial display, studies have been unable to find support for this, as the tail curling does not vary when another member of the same species is present.
Conservation status and extinctions
The conservation status of the species in this family varies greatly. Several species, for example Leiocephalus carinatus, are common and widespread. Others are rare and highly threatened, especially those restricted to a single small island or a single location on a larger island, like the critically endangered Leiocephalus (barahonensis) altavelensis from Alto Velo Island and critically endangered Leiocephalus onaneyi from Guantánamo Province in Cuba. Primary threats to their survival are habitat loss (for example, expanding agriculture, charcoal production and grazing goats) and introduced predators (for example, small Indian mongoose).