Burton's legless lizard (Lialis burtonis ) is a species of lizard found only in Australia and Papua New Guinea. These lizards lack forelegs, having only rudimentary hind legs and that's why are also called "flap-footed lizards" and "snake-lizards".
Burton's legless lizard has significant morphological adaptations to help it deal with large struggling prey items. The first adaptation is a skull with an elongated snout that may, along with its pointed, recurved, and hinged teeth, be an adaptation that assists it in gripping its prey. In addition, this elongated snout may also promote binocular vision which would allow strikes to be more accurately directed. Another adaptation that assists Burton's legless lizard to hold its prey is its flexible mesokinetic and hypokinetic joints which allow its jaws to encircle prey. Lastly, the ability of the species to retract its eyes is of key importance as it is a visual predator that relies on eyesight and this adaptation effectively protects it during conflict.
Burton's legless lizards occur throughout Australia but they are absent in parts of southern Australia including Tasmania. They are also found in a small area of Papua New Guinea. Burton's legless lizards live in a variety of habitats from deserts to the margins of rainforests but they are absent in southern alpine areas and extreme northern deserts. They prefer low vegetation or debris on the ground such as leaf litter. In areas where leaf litter is not as readily available, these lizards will use grasses, abandoned burrows, and other shelters that they can find.
Burton's legless lizards are mainly diurnal feeders but they can also be active at any time. This is because most of their prey is active during the daylight hours but the lizards also tend to be nocturnal to reduce risks of hyperthermia during hot conditions and reduce risks of predation from diurnal predators like raptors. Hunting at night also improves the chances of staying unnoticed while ambushing prey. Burton's legless lizards hunt visually and strike based on movement and require shelter to ambush their prey. Shelter is also required to hide from predators and plays a key role in lizard thermoregulation. Deep leaf litter, for example, is a very good shelter as individuals can bury themselves at an appropriate depth to regulate temperature and remain hidden at the same time. Burton's legless lizards also use caudal luring as a feeding strategy which is rare in lizards. They also have a tendency to vocalize, especially, when feeling threatened. Furthermore, if they are seized by a predator they can drop their tail like many other lizards.
Burton's legless lizards are carnivores. They feed almost exclusively on other lizards preferring skinks as the main prey item but other legless lizards, geckos, and dragons are also taken. In addition, they can eat small snakes on rare occasions.
Burton's legless lizards breed at similar times throughout Australia, usually from September until summer. Females are oviparous and lay eggs from November to January; however, reproduction can occur at any time outside of the usual breeding season and females are capable of laying more than one clutch each year. Females lay their clutches under logs or rocks, on the ground, under leaf litter, and sometimes in the nests of sugar ants. Clutches can be laid in quick succession with each clutch containing 1 to 3 tough, leathery eggs. Females can sometimes nest communally and up to 20 eggs have been found in a nest. It has been discovered that females of this species can delay reproduction to a later time or to reproduce through parthenogenesis which does not require mating to be successful. When baby Burton's legless lizards hatch they are approximately 13 cm (5 in) long.
Burton's legless lizards don't have any major threats at present. They are Australia's most widespread reptiles and there has been no indication that they are rare or rapidly declining.
According to the IUCN Red List, Burton's legless lizard is common throughout its range but no overall population estimate is available. Currently, this species is classified as Least Concern (LC) on the IUCN Red List and its numbers today are stable.
