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Lizards
Temporal range: Middle Jurassic – Holocene, 168–0 Ma
Clockwise from top left: veiled chameleon (Chamaeleo calyptratus), rock monitor (Varanus albigularis), common blue-tongued skink (Tiliqua scincoides), Italian wall lizard (Podarcis sicula), giant leaf-tailed gecko (Uroplatus fimbriatus), and legless lizard (Anelytropsis papillosus)
Clockwise from top left: veiled chameleon (Chamaeleo calyptratus), rock monitor (Varanus albigularis), common blue-tongued skink (Tiliqua scincoides), Italian wall lizard (Podarcis sicula), giant leaf-tailed gecko (Uroplatus fimbriatus), and legless lizard (Anelytropsis papillosus)
Scientific classificationEdit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Superorder: Lepidosauria
Order: Squamata
Groups included
Anguimorpha
Dibamidae
Gekkota
Iguanomorpha
Lacertoidea
Scincomorpha
Range of the lizards, all species.
Range of the lizards, all species.
Squamates that are not considered lizards
Serpentes
Amphisbaenia (sometimes)
†Mosasauroidea

Lizard is the common name used for all squamate reptiles other than snakes (and to a lesser extent amphisbaenians), encompassing over 7,000 species,[1] ranging across all continents except Antarctica, as well as most oceanic island chains. The grouping is paraphyletic as some lizards are more closely related to snakes than they are to other lizards. Lizards range in size from chameleons and geckos a few centimeters long to the 3-meter-long Komodo dragon.

Most lizards are quadrupedal, running with a strong side-to-side motion. Some lineages (known as "legless lizards") have secondarily lost their legs, and have long snake-like bodies. Some lizards, such as the forest-dwelling Draco, are able to glide. They are often territorial, the males fighting off other males and signalling, often with bright colours, to attract mates and to intimidate rivals. Lizards are mainly carnivorous, often being sit-and-wait predators; many smaller species eat insects, while the Komodo eats mammals as big as water buffalo.

Lizards make use of a variety of antipredator adaptations, including venom, camouflage, reflex bleeding, and the ability to sacrifice and regrow their tails.

Anatomy

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Largest and smallest

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The adult length of species within the suborder ranges from a few centimeters for chameleons such as Brookesia micra and geckos such as Sphaerodactylus ariasae[2] to nearly 3 m (10 ft) in the case of the largest living varanid lizard, the Komodo dragon.[3] Most lizards are fairly small animals.

Distinguishing features

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A young Mediterranean house gecko in the process of moulting.

Lizards typically have rounded torsos, elevated heads on short necks, four limbs and long tails, although some are legless.[4] Lizards and snakes share a movable quadrate bone, distinguishing them from the rhynchocephalians, which have more rigid diapsid skulls.[5] Some lizards such as chameleons have prehensile tails, assisting them in climbing among vegetation.[6]

As in other reptiles, the skin of lizards is covered in overlapping scales made of keratin. This provides protection from the environment and reduces water loss through evaporation. This adaptation enables lizards to thrive in some of the driest deserts on earth. The skin is tough and leathery, and is shed (sloughed) as the animal grows. Unlike snakes which shed the skin in a single piece, lizards slough their skin in several pieces. The scales may be modified into spines for display or protection, and some species have bone osteoderms underneath the scales.[6][7]

Red tegu (Tupinambis rufescens) skull, showing teeth of differing types

The dentitions of lizards reflect their wide range of diets, including carnivorous, insectivorous, omnivorous, herbivorous, nectivorous, and molluscivorous. Species typically have uniform teeth suited to their diet, but several species have variable teeth, such as cutting teeth in the front of the jaws and crushing teeth in the rear. Most species are pleurodont, though agamids and chameleons are acrodont.[8][6]

The tongue can be extended outside the mouth, and is often long. In the beaded lizards, whiptails and monitor lizards, the tongue is forked and used mainly or exclusively to sense the environment, continually flicking out to sample the environment, and back to transfer molecules to the vomeronasal organ responsible for chemosensation, analogous to but different from smell or taste. In geckos, the tongue is used to lick the eyes clean: they have no eyelids. Chameleons have very long sticky tongues which can be extended rapidly to catch their insect prey.[6]

Three lineages, the geckos, anoles, and chameleons, have modified the scales under their toes to form adhesive pads, highly prominent in the first two groups. The pads are composed of millions of tiny setae (hair-like structures) which fit closely to the substrate to adhere using van der Waals forces; no liquid adhesive is needed.[9] In addition, the toes of chameleons are divided into two opposed groups on each foot (zygodactyly), enabling them to perch on branches as birds do.[a][6]

Physiology

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Locomotion

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Adhesive pads enable geckos to climb vertically.

Aside from legless lizards, most lizards are quadrupedal and move using gaits with alternating movement of the right and left limbs with substantial body bending. This body bending prevents significant respiration during movement, limiting their endurance, in a mechanism called Carrier's constraint. Several species can run bipedally,[10] and a few can prop themselves up on their hindlimbs and tail while stationary. Several small species such as those in the genus Draco can glide: some can attain a distance of 60 metres (200 feet), losing 10 metres (33 feet) in height.[11] Some species, like geckos and chameleons, adhere to vertical surfaces including glass and ceilings.[9] Some species, like the common basilisk, can run across water.[12]

Senses

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Lizards make use of their senses of sight, touch, olfaction and hearing like other vertebrates. The balance of these varies with the habitat of different species; for instance, skinks that live largely covered by loose soil rely heavily on olfaction and touch, while geckos depend largely on acute vision for their ability to hunt and to evaluate the distance to their prey before striking. Monitor lizards have acute vision, hearing, and olfactory senses. Some lizards make unusual use of their sense organs: chameleons can steer their eyes in different directions, sometimes providing non-overlapping fields of view, such as forwards and backwards at once. Lizards lack external ears, having instead a circular opening in which the tympanic membrane (eardrum) can be seen. Many species rely on hearing for early warning of predators, and flee at the slightest sound.[13]

Nile monitor using its tongue for smell

As in snakes and many mammals, all lizards have a specialised olfactory system, the vomeronasal organ, used to detect pheromones. Monitor lizards transfer scent from the tip of their tongue to the organ; the tongue is used only for this information-gathering purpose, and is not involved in manipulating food.[14][13]

Skeleton of bearded dragon (pogona sp.) on display at the Museum of Osteology.

Some lizards, particularly iguanas, have retained a photosensory organ on the top of their heads called the parietal eye, a basal ("primitive") feature also present in the tuatara. This "eye" has only a rudimentary retina and lens and cannot form images, but is sensitive to changes in light and dark and can detect movement. This helps them detect predators stalking it from above.[15]

Venom

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Some lizards including the Gila monster are venomous.
Further information: Evolution of snake venom

Until 2006 it was thought that the Gila monster and the Mexican beaded lizard were the only venomous lizards. However, several species of monitor lizards, including the Komodo dragon, produce powerful venom in their oral glands. Lace monitor venom, for instance, causes swift loss of consciousness and extensive bleeding through its pharmacological effects, both lowering blood pressure and preventing blood clotting. Nine classes of toxin known from snakes are produced by lizards. The range of actions provides the potential for new medicinal drugs based on lizard venom proteins.[16][17]

Genes associated with venom toxins have been found in the salivary glands of a wide range of lizards, including species traditionally thought of as non-venomous, such as iguanas and bearded dragons. This suggests that these genes evolved in the common ancestor of lizards and snakes, some 200 million years ago (forming a single clade, the Toxicofera).[16] However, most of these putative venom genes were "housekeeping genes" found in all cells and tissues, including skin and cloacal scent glands. The genes in question may thus be evolutionary precursors of venom genes.[18]

Respiration

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Recent studies (2013 and 2014) on the lung anatomy of the savannah monitor and green iguana found them to have a unidirectional airflow system, which involves the air moving in a loop through the lungs when breathing. This was previously thought to only exist in the archosaurs (crocodilians and birds). This may be evidence that unidirectional airflow is an ancestral trait in diapsids.[19][20]

Reproduction and life cycle

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Trachylepis maculilabris skinks mating

As with all amniotes, lizards rely on internal fertilisation and copulation involves the male inserting one of his hemipenes into the female's cloaca.[21] Female lizards also have hemiclitorises, a doubled clitoris. The majority of species are oviparous (egg laying). The female deposits the eggs in a protective structure like a nest or crevice or simply on the ground.[22] Depending on the species, clutch size can vary from 4–5 percent of the females body weight to 40–50 percent and clutches range from one or a few large eggs to dozens of small ones.[23]

Two pictures of an eastern fence lizard egg layered onto one image.

In most lizards, the eggs have leathery shells to allow for the exchange of water, although more arid-living species have calcified shells to retain water. Inside the eggs, the embryos use nutrients from the yolk. Parental care is uncommon and the female usually abandons the eggs after laying them. Brooding and protection of eggs do occur in some species. The female prairie skink uses respiratory water loss to maintain the humidity of the eggs which facilitates embryonic development. In lace monitors, the young hatch close to 300 days, and the female returns to help them escape the termite mound where the eggs were laid.[22]

Around 20 percent of lizard species reproduce via viviparity (live birth). This is particularly common in Anguimorphs. Viviparous species give birth to relatively developed young which look like miniature adults. Embryos are nourished via a placenta-like structure.[24] A minority of lizards have parthenogenesis (reproduction from unfertilised eggs). These species consist of all females who reproduce asexually with no need for males. This is known to occur in various species of whiptail lizards.[25] Parthenogenesis was also recorded in species that normally reproduce sexually. A captive female Komodo dragon produced a clutch of eggs, despite being separated from males for over two years.[26]

Sex determination in lizards can be temperature-dependent. The temperature of the eggs' micro-environment can determine the sex of the hatched young: low temperature incubation produces more females while higher temperatures produce more males. However, some lizards have sex chromosomes and both male heterogamety (XY and XXY) and female heterogamety (ZW) occur.[25]

Aging

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A significant component of aging in the painted dragon lizard Ctenophorus pictus is fading breeding colors.[27] By manipulating superoxide levels (using a superoxide dismutase mimetic) it was shown that this fading coloration is likely due to gradual loss with lizard age of an innate capacity for antioxidation due to increasing DNA damage.[27]

Behaviour

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Diurnality and thermoregulation

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The majority of lizard species are active during the day,[28] though some are active at night, notably geckos. As ectotherms, lizards have a limited ability to regulate their body temperature, and must seek out and bask in sunlight to gain enough heat to become fully active.[29] Thermoregulation behavior can be beneficial in the short term for lizards as it allows the ability to buffer environmental variation and endure climate warming.[30]

In high altitudes, the Podarcis hispaniscus responds to higher temperature with a darker dorsal coloration to prevent UV-radiation and background matching. Their thermoregulatory mechanisms also allow the lizard to maintain their ideal body temperature for optimal mobility.[31]

Territoriality

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Fighting male sand lizards

Most social interactions among lizards are between breeding individuals.[28] Territoriality is common and is correlated with species that use sit-and-wait hunting strategies. Males establish and maintain territories that contain resources that attract females and which they defend from other males. Important resources include basking, feeding, and nesting sites as well as refuges from predators. The habitat of a species affects the structure of territories, for example, rock lizards have territories atop rocky outcrops.[32] Some species may aggregate in groups, enhancing vigilance and lessening the risk of predation for individuals, particularly for juveniles.[33] Agonistic behaviour typically occurs between sexually mature males over territory or mates and may involve displays, posturing, chasing, grappling and biting.[32]

Communication

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Main article: Lizard communication
A green anole (Anolis carolinensis) signalling with its extended dewlap

Lizards signal both to attract mates and to intimidate rivals. Visual displays include body postures and inflation, push-ups, bright colours, mouth gapings and tail waggings. Male anoles and iguanas have dewlaps or skin flaps which come in various sizes, colours and patterns and the expansion of the dewlap as well as head-bobs and body movements add to the visual signals.[34][6] Some species have deep blue dewlaps and communicate with ultraviolet signals.[28] Blue-tongued skinks will flash their tongues as a threat display.[35] Chameleons are known to change their complex colour patterns when communicating, particularly during agonistic encounters. They tend to show brighter colours when displaying aggression[36] and darker colours when they submit or "give up".[37]

Several gecko species are brightly coloured; some species tilt their bodies to display their coloration. In certain species, brightly coloured males turn dull when not in the presence of rivals or females. While it is usually males that display, in some species females also use such communication. In the bronze anole, head-bobs are a common form of communication among females, the speed and frequency varying with age and territorial status. Chemical cues or pheromones are also important in communication. Males typically direct signals at rivals, while females direct them at potential mates. Lizards may be able to recognise individuals of the same species by their scent.[34]

Tokay gecko mating call
Mating call of a male Tokay gecko
Problems playing this file? See media help.

Acoustic communication is less common in lizards. Hissing, a typical reptilian sound, is mostly produced by larger species as part of a threat display, accompanying gaping jaws. Some groups, particularly geckos, snake-lizards, and some iguanids, can produce more complex sounds and vocal apparatuses have independently evolved in different groups. These sounds are used for courtship, territorial defense and in distress, and include clicks, squeaks, barks and growls. The mating call of the male tokay gecko is heard as "tokay-tokay!".[35][34][38] Tactile communication involves individuals rubbing against each other, either in courtship or in aggression.[34] Some chameleon species communicate with one another by vibrating the substrate that they are standing on, such as a tree branch or leaf.[39]

Defence

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Lizards are normally quick and agile to easily outrun attackers.[40]

Ecology

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Lizard in tree. Many species are tree-dwelling
A lizard from Thar desert
A lizard from Thar desert

Distribution and habitat

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Lizards are found worldwide, excluding the far north and Antarctica, and some islands. They can be found in elevations from sea level to 5,000 m (16,000 ft). They prefer warmer, tropical climates but are adaptable and can live in all but the most extreme environments. Lizards also exploit a number of habitats; most primarily live on the ground, but others may live in rocks, on trees, underground and even in water.[40] The marine iguana is adapted for life in the sea.[6]

Diet

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Western green lizard ambushes its grasshopper prey.

The majority of lizard species are predatory and the most common prey items are small, terrestrial invertebrates, particularly insects.[6][41] Many species are sit-and-wait predators though others may be more active foragers.[42] Chameleons prey on numerous insect species, such as beetles, grasshoppers and winged termites as well as spiders. They rely on persistence and ambush to capture these prey. An individual perches on a branch and stays perfectly still, with only its eyes moving. When an insect lands, the chameleon focuses its eyes on the target and slowly moves toward it before projecting its long sticky tongue which, when hauled back, brings the attached prey with it. Geckos feed on crickets, beetles, termites and moths.[6][41]

Termites are an important part of the diets of some species of Autarchoglossa, since, as social insects, they can be found in large numbers in one spot. Ants may form a prominent part of the diet of some lizards, particularly among the lacertas.[6][41] Horned lizards are also well known for specializing on ants. Due to their small size and indigestible chitin, ants must be consumed in large amounts, and ant-eating lizards have larger stomachs than even herbivorous ones.[43] Species of skink and alligator lizards eat snails and their power jaws and molar-like teeth are adapted for breaking the shells.[6][41]

Young Komodo dragon feeding on a water buffalo carcass
Marine iguana foraging under water at Galápagos Islands, Ecuador.

Larger species, such as monitor lizards, can feed on larger prey including fish, frogs, birds, mammals and other reptiles. Prey may be swallowed whole and torn into smaller pieces. Both bird and reptile eggs may also be consumed as well. Gila monsters and beaded lizards climb trees to reach both the eggs and young of birds. Despite being venomous, these species rely on their strong jaws to kill prey. Mammalian prey typically consists of rodents and leporids; the Komodo dragon can kill prey as large as water buffalo. Dragons are prolific scavengers, and a single decaying carcass can attract several from 2 km (1.2 mi) away. A 50 kg (110 lb) dragon is capable of consuming a 31 kg (68 lb) carcass in 17 minutes.[41]

Around 2 percent of lizard species, including many iguanids, are herbivores. Adults of these species eat plant parts like flowers, leaves, stems and fruit, while juveniles eat more insects. Plant parts can be hard to digest, and, as they get closer to adulthood, juvenile iguanas eat faeces from adults to acquire the microflora necessary for their transition to a plant-based diet. Perhaps the most herbivorous species is the marine iguana which dives 15 m (49 ft) to forage for algae, kelp and other marine plants. Some non-herbivorous species supplement their insect diet with fruit, which is easily digested.[6][41]

Antipredator adaptations

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The frilled-neck lizard with fully extended frill. The frilled neck serves to make it look bigger than it actually is.
Main article: Antipredator adaptation

Lizards have a variety of antipredator adaptations, including running and climbing, venom, camouflage, tail autotomy, and reflex bleeding.

Camouflage

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Lizards exploit a variety of different camouflage methods. Many lizards are disruptively patterned. In some species, such as Aegean wall lizards, individuals vary in colour, and select rocks which best match their own colour to minimise the risk of being detected by predators.[44] The Moorish gecko is able to change colour for camouflage: when a light-coloured gecko is placed on a dark surface, it darkens within an hour to match the environment.[45] The chameleons in general use their ability to change their coloration for signalling rather than camouflage, but some species such as Smith's dwarf chameleon do use active colour change for camouflage purposes.[46]

The flat-tail horned lizard's body is coloured like its desert background, and is flattened and fringed with white scales to minimise its shadow.[47]

Autotomy

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A skink tail continuing to move after autotomy

Many lizards, including geckos and skinks, are capable of shedding their tails (autotomy). The detached tail, sometimes brilliantly coloured, continues to writhe after detaching, distracting the predator's attention from the fleeing prey. Lizards partially regenerate their tails over a period of weeks. Some 326 genes are involved in regenerating lizard tails.[48] The fish-scale gecko Geckolepis megalepis sheds patches of skin and scales if grabbed.[49]

Escape, playing dead, reflex bleeding

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Many lizards attempt to escape from danger by running to a place of safety;[50][b] for example, wall lizards can run up walls and hide in holes or cracks.[9] Horned lizards adopt differing defences for specific predators. They may play dead to deceive a predator that has caught them; attempt to outrun the rattlesnake, which does not pursue prey; but stay still, relying on their cryptic coloration, for Masticophis whip snakes which can catch even swift prey. If caught, some species such as the greater short-horned lizard puff themselves up, making their bodies hard for a narrow-mouthed predator like a whip snake to swallow. Finally, horned lizards can squirt blood at cat and dog predators from a pouch beneath its eyes, to a distance of about two metres (6.6 feet); the blood tastes foul to these attackers.[52]

Evolution

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Fossil history

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Fossil lizard Dalinghosaurus longidigitus, Early Cretaceous, China

The closest living relatives of lizards are rhynchocephalians, a once diverse order of reptiles, of which is there is now only one living species, the tuatara of New Zealand. Some reptiles from the Early and Middle Triassic, like Sophineta and Megachirella, are suggested to be stem-group squamates, more closely related to modern lizards than rhynchocephalians, however, their position is disputed, with some studies recovering them as less closely related to squamates than rhynchocephalians are.[53] The oldest undisputed lizards date to the Middle Jurassic, from remains found In Europe, Asia and North Africa.[54] Lizard morphological and ecological diversity substantially increased over the course of the Cretaceous.[55] In the Palaeogene, lizard body sizes in North America peaked during the middle of the period.[56]

Mosasaurs likely evolved from an extinct group of aquatic lizards[57] known as aigialosaurs in the Early Cretaceous. Dolichosauridae is a family of Late Cretaceous aquatic varanoid lizards closely related to the mosasaurs.[58][59]

Phylogeny

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External

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The position of the lizards and other Squamata among the reptiles was studied using fossil evidence by Rainer Schoch and Hans-Dieter Sues in 2015. Lizards form about 60% of the extant non-avian reptiles.[60]

Archelosauria

Internal

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Both the snakes and the Amphisbaenia (worm lizards) are clades deep within the Squamata (the smallest clade that contains all the lizards), so "lizard" is paraphyletic.[61] The cladogram is based on genomic analysis by Wiens and colleagues in 2012 and 2016.[62][63] Excluded taxa are shown in upper case on the cladogram.

Squamata
Dibamia

Dibamidae

Bifurcata
Gekkota
Unidentata

Taxonomy

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Main article: List of Lacertilia families
Artistic restoration of a mosasaur, Prognathodon

In the 13th century, lizards were recognized in Europe as part of a broad category of reptiles that consisted of a miscellany of egg-laying creatures, including "snakes, various fantastic monsters, […], assorted amphibians, and worms", as recorded by Vincent of Beauvais in his Mirror of Nature.[64] The seventeenth century saw changes in this loose description. The name Sauria was coined by James Macartney (1802);[65] it was the Latinisation of the French name Sauriens, coined by Alexandre Brongniart (1800) for an order of reptiles in the classification proposed by the author, containing lizards and crocodilians,[66] later discovered not to be each other's closest relatives. Later authors used the term "Sauria" in a more restricted sense, i.e. as a synonym of Lacertilia, a suborder of Squamata that includes all lizards but excludes snakes. This classification is rarely used today because Sauria so-defined is a paraphyletic group. It was defined as a clade by Jacques Gauthier, Arnold G. Kluge and Timothy Rowe (1988) as the group containing the most recent common ancestor of archosaurs and lepidosaurs (the groups containing crocodiles and lizards, as per Mcartney's original definition) and all its descendants.[67] A different definition was formulated by Michael deBraga and Olivier Rieppel (1997), who defined Sauria as the clade containing the most recent common ancestor of Choristodera, Archosauromorpha, Lepidosauromorpha and all their descendants.[68] However, these uses have not gained wide acceptance among specialists.

Suborder Lacertilia (Sauria) – (lizards)

The slowworms, Anguis, are among over twenty groups of lizards that have convergently evolved a legless body plan.[69]

Convergence

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Lizards have frequently evolved convergently, with multiple groups independently developing similar morphology and ecological niches. Anolis ecomorphs have become a model system in evolutionary biology for studying convergence.[70] Limbs have been lost or reduced independently over two dozen times across lizard evolution, including in the Anniellidae, Anguidae, Cordylidae, Dibamidae, Gymnophthalmidae, Pygopodidae, and Scincidae; snakes are just the most famous and species-rich group of Squamata to have followed this path.[69]

Relationship with humans

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Interactions and uses by humans

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Most lizard species are harmless to humans. Only the largest lizard species, the Komodo dragon, which reaches 3.3 m (11 ft) in length and weighs up to 166 kg (366 lb), has been known to stalk, attack, and, on occasion, kill humans. An eight-year-old Indonesian boy died from blood loss after an attack in 2007.[71]

Green iguanas (Iguana iguana), are popular pets.

Numerous species of lizard are kept as pets, including bearded dragons,[72] iguanas, anoles,[73] and geckos (such as the popular leopard gecko).[72]Monitor lizards such as the savannah monitor and tegus such as the Argentine tegu and red tegu are also kept.

Green iguanas are eaten in Central America, where they are sometimes referred to as "chicken of the tree" after their habit of resting in trees and their supposedly chicken-like taste,[74] while spiny-tailed lizards are eaten in Africa. In North Africa, Uromastyx species are considered dhaab or 'fish of the desert' and eaten by nomadic tribes.[75]

Red tegu drinking water out of a dispenser.

Lizards such as the Gila monster produce toxins with medical applications. Gila toxin reduces plasma glucose; the substance is now synthesized for use in the anti-diabetes drug exenatide (Byetta).[17] Another toxin from Gila monster saliva has been studied for use as an anti-Alzheimer's drug.[76]

In culture

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Lizards appear in myths and folktales around the world. In Australian Aboriginal mythology, Tarrotarro, the lizard god, split the human race into male and female, and gave people the ability to express themselves in art. A lizard king named Mo'o features in Hawaii and other cultures in Polynesia. In the Amazon, the lizard is the king of beasts, while among the Bantu of Africa, the god UNkulunkulu sent a chameleon to tell humans they would live forever, but the chameleon was held up, and another lizard brought a different message, that the time of humanity was limited.[77] A popular legend in Maharashtra tells the tale of how a common Indian monitor, with ropes attached, was used to scale the walls of the fort in the Battle of Sinhagad.[78]

Lizards in many cultures share the symbolism of snakes, especially as an emblem of resurrection. This may have derived from their regular molting. The motif of lizards on Christian candle holders probably alludes to the same symbolism. According to Jack Tresidder, in Egypt and the Classical world, they were beneficial emblems, linked with wisdom. In African, Aboriginal and Melanesian folklore they are linked to cultural heroes or ancestral figures.[79]

Notes

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References

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Further reading

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[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Lizard

View on Grokipedia
from Grokipedia
Lizards are a diverse group of squamate reptiles within the suborder , distinguished from snakes and amphisbaenians by features such as typically four limbs, movable eyelids, external ear openings, and a flexible with kinetic joints. With 7,905 recognized as of September 2025, lizards represent the largest subgroup of the approximately 12,311 extant squamates and exhibit remarkable morphological and ecological variation. They inhabit virtually every terrestrial and some arboreal or aquatic environments across all continents except , from arid deserts and rocky outcrops to tropical rainforests and urban areas. As ectothermic vertebrates, lizards regulate body temperature primarily through behavioral thermoregulation, such as basking in sunlight or seeking shade, and they periodically shed their skin to accommodate growth. Their sizes range dramatically, from the tiniest known reptile—the nano-chameleon (Brookesia nana), with a body length of 1.35 cm—to the massive Komodo dragon (Varanus komodoensis), which can exceed 3 meters and weigh over 70 kg. Most species are small, under 20 cm, but all share scaly integument that provides protection and reduces water loss in varied climates. Ecologically, lizards play crucial roles as predators, controlling invertebrate populations like and arachnids, while larger prey on small vertebrates; some, particularly iguanas and certain agamids, have evolved herbivorous diets supplemented by fruits and vegetation. They serve as prey for birds, mammals, and other reptiles, contributing to dynamics, and many aid in or aeration through their foraging behaviors. is predominantly oviparous, with females laying leathery eggs in clutches buried in or hidden in crevices, though a minority, such as some skinks and night lizards, are viviparous, giving birth to live young. Notable adaptations include caudal —the ability to voluntarily detach the to escape predators—followed by regeneration, though the regrown is often shorter and less functional. Lizards display a spectrum of locomotion, from rapid sprinting and to gliding in like the Draco lizards, and their color-changing abilities in chameleons and some anoles facilitate and . While most are harmless, a few, like the and , possess venom for subduing prey, highlighting the group's evolutionary versatility.

Anatomy

Size variations

Lizards exhibit remarkable size diversity, ranging from some of the smallest vertebrates to the largest extant reptiles. The Komodo dragon (Varanus komodoensis) represents the heaviest lizard species, with adults reaching lengths of up to 3 meters and weights of up to approximately 150 kilograms. Another notably large species is the crocodile monitor (Varanus salvadorii), which can grow to over 3.2 meters in length, making it the longest lizard species. At the opposite extreme, the smallest lizards include the Jaragua gecko (), with adults measuring just 1.6 centimeters from snout to tail base. The nano-chameleon (), a dwarf chameleon species, has adult males with a snout-to-vent length of just 1.35 centimeters and is the smallest known reptile as of 2025. Several ecological factors influence lizard body size variation. plays a key role, as environments can drive through reduced predation pressure or due to limited resources, allowing lizards to evolve larger or smaller forms accordingly. Predation intensity and resource availability further shape size, with lower predator presence on islands enabling larger body sizes and scarcer food constraining growth in resource-poor settings. Allometric scaling governs growth patterns, where body size disproportionately affects traits like metabolic rate and limb proportions, often leading to reduced limbs in the smallest species for enhanced maneuverability in microhabitats. Recent research highlights 's role in size evolution. For instance, a 2024 study on agamid lizards along elevational gradients suggests body size variations that may relate to thermal conditions and adaptive responses to .

Morphological features

Lizards possess a scaly composed of keratinized epidermal scales that overlap and provide , flexibility, and . In certain species, such as tegus (), the skin incorporates osteoderms—bony dermal plates embedded within or beneath the scales—that enhance armor-like defense against predators. Some lizards exhibit color-changing abilities through dermal chromatophores, cells including melanophores, xanthophores, and iridophores that expand or contract to alter coloration for or signaling. Most lizards are quadrupedal, featuring four limbs with pentadactyl hands and feet ending in sharp, curved claws adapted for gripping surfaces. Arboreal species, such as , often have prehensile tails that coil around branches for stability and . Limb reduction occurs in some lineages, notably skinks (Scincidae) and anguids (Anguidae), where limbs are shortened or absent, facilitating burrowing or snake-like movement. The is kinetic, allowing independent movement of the upper relative to the braincase, which aids in capturing and swallowing large prey. is typically acrodont in agamids and , with teeth fused directly to the jawbone margins, or pleurodont in most other lizards, where teeth attach to the inner side of the without sockets. Lizards form a paraphyletic group within , excluding snakes, which are derived from within the lizard clade. As amniotes, they produce eggs with protective amniotic membranes, , and , enabling terrestrial development. Lizards are distinguished from snakes by the presence of movable eyelids, external ear openings, and transverse rows of ventral scales, and from amphibians by their fully keratinized, scaly skin lacking mucous glands.

Physiology

Locomotion

Lizards employ a variety of gaits adapted to their environments, primarily quadrupedal walking and running on terrestrial substrates, which involve coordinated limb movements where diagonally opposite feet advance together for stability. During rapid locomotion, many species transition to bipedal running, raising the forebody off the ground to achieve higher speeds, as observed in species like the zebra-tailed lizard (Callisaurus draconoides). Climbing is facilitated by sprawling limb postures and grasping abilities, allowing arboreal lizards to navigate vertical surfaces efficiently. A remarkable example of ballistic movement is seen in the common basilisk (Basiliscus basiliscus), which can sprint bipedally across water surfaces at speeds up to 1.5 m/s by slapping its hind feet to create an air cavity for support and stroking to generate thrust and lift, preventing submersion. Specialized adaptations enhance locomotion in challenging habitats. Geckos, such as the (Gekko gecko), utilize adhesive toe pads covered in millions of microscopic setae that exploit van der Waals forces for reversible attachment, enabling rapid running on vertical walls and inverted ceilings at speeds approaching 1 m/s with step durations as short as 20 ms, while maintaining high and adhesion without slipping. In desert environments, fringe-toed lizards like Phrynocephalus mystaceus possess elongated fringes on their toes that facilitate sand swimming—a undulatory burrowing motion through loose substrate—by improving burying efficiency and reducing drag, though these structures do not significantly affect sprint speeds on sand surfaces. The tail plays a crucial role in locomotion across lizard species, serving as a counterbalance during running and climbing to stabilize the body and enhance maneuverability. In aquatic or semi-aquatic contexts, the tail provides propulsion through lateral undulations, acting like a or , as in monitor lizards (Varanus spp.) where it generates thrust during swimming. Some monitors also employ tail-assisted saltation—sudden leaps or bounds—integrating tail flexion for pitch control and forward momentum in evasive maneuvers. Lizard locomotion balances efficiency through biomechanical principles like ballistic recovery in limb kinematics, where elastic elements in tendons store and release during strides, contrasting with dynamic similarity scaling that maintains proportional limb movements across body sizes for optimal performance. Studies on whiptail lizards (Aspidoscelis spp.) demonstrate sprint capabilities up to approximately 25 km/h in bipedal bursts, highlighting how limb length and muscle power contribute to efficient high-speed evasion without excessive expenditure.

Senses

Lizards possess a range of sensory adaptations that enable them to perceive their environment effectively, with vision playing a dominant role in many species. Most diurnal lizards exhibit tetrachromatic , including sensitivity to (UV) light, which allows them to detect visual signals invisible to humans. This UV sensitivity is particularly important for mate selection, as many lizards display UV-reflective patterns on their skin that signal reproductive fitness. The structure of the lizard eye includes a lens that provides accommodation for focusing on near and far objects, aiding in and . Olfaction in lizards is mediated primarily through the , also known as Jacobson's organ, which detects chemical cues such as pheromones for social and reproductive behaviors. Lizards sample airborne and substrate chemicals by flicking their tongues, which transfer particles to the for analysis; this behavior is especially pronounced in monitor lizards for tracking prey. The enhances directional olfaction by comparing chemical concentrations on each side. Hearing in lizards relies on a tympanic membrane that vibrates in response to airborne sounds, transmitting signals via the to the . Many show greater sensitivity to substrate-borne vibrations than to high-frequency airborne sounds, allowing detection of approaching predators or prey through ground contact. This vibrational sensitivity is facilitated by the body and limbs acting as receptors, complementing the . Tactile senses are provided by mechanoreceptors embedded in the scales and skin, enabling lizards to sense touch, pressure, and texture for navigating and detecting nearby movements. Nocturnal , such as geckos, exhibit specialized visual adaptations for low-light conditions, including large corneas and a high of rod cells that provide 350 times more sensitive than humans, aiding in at night. These adaptations underscore the diverse sensory toolkit lizards employ for survival across varied habitats.

Venom

Five lizard species in the genus (family ) are recognized as truly : the (Heloderma suspectum) and four species in the beaded lizard complex (H. horridum, H. alvarezi, H. charlesbogerti, H. exasperatum). These lizards possess specialized glands in their lower jaws and grooved teeth that facilitate delivery. In contrast, some members of the family , such as monitor lizards including the (Varanus komodoensis), produce mild toxins in their oral glands, which contribute to effects but lack a fully developed system like that of Helodermatidae. The venom of is a complex mixture of proteins and peptides, including the gilatoxin, a kallikrein-like that acts as a primary lethal component by lowering and affecting . Other key constituents encompass neurotoxins, such as helothermine, which inhibits calcium channels; phospholipases A2 that promote tissue damage; and anticoagulants like , which facilitate venom spread. In varanids, the toxic saliva contains a broader array of , anticoagulants, and hypotensive agents, though these are generally less potent and serve more as aids in subduing prey through infection and blood loss rather than rapid paralysis. Notably, the exendin-4, found exclusively in venom, shares structural similarity with human (GLP-1) but exhibits greater stability, enabling prolonged physiological effects. Venom delivery in occurs via a mechanism: the lizard bites and holds onto the victim, using mandibular movements to force from the sublingual glands along channels in the grooved teeth and into the wound. This method contrasts with the rapid injection seen in snakes, resulting in slower but persistent . Effects on prey or humans include intense localized , rapid swelling and at the bite site, systemic due to kallikrein-induced , and potential or , though fatalities are rare with prompt medical care. Varanid envenomations similarly cause and but often lead to prolonged from effects. The evolution of lizard venom systems reflects independent refinements within the clade, encompassing anguimorph lizards (including and ) and advanced , with a shared ancestral origin back approximately 170-200 million years. However, the distinct biochemical profiles— venoms emphasizing kallikreins and nerve growth factors, versus varanid venoms rich in bacteriotoxins—indicate lineage-specific adaptations for predation and defense. This evolutionary divergence highlights venom's role in overcoming larger or more mobile prey in arid environments. Medically, Gila monster venom has yielded transformative applications, particularly through exendin-4, which inspired the development of , a synthetic approved in 2005 for managing by enhancing insulin secretion, slowing gastric emptying, and reducing postprandial glucose levels. 's resistance to enzymatic degradation—unlike native GLP-1—allows twice-daily dosing, improving glycemic control in patients with limited beta-cell function. Ongoing research explores further derivatives for and neurodegenerative conditions, underscoring venom's potential beyond .

Respiration

Lizards respire primarily through lungs, employing a combination of costal pumping via and buccal or gular force to ventilate the , as they lack a muscular diaphragm separating the thoracic and abdominal regions. This mechanism relies on expansion and contraction of the and abdominal walls to draw air into and expel it from the lungs, with abdominal muscles playing a key role in expiration. In many species, such as varanid lizards, gular pumping supplements lung ventilation, particularly to overcome locomotor constraints like reduced thoracic expansion during sprinting. The lungs of lizards exhibit a multicameral structure, divided into multiple chambers or sacs that enhance efficiency through increased surface area and compartmentalized . This partitioned design, observed across various squamate lineages, facilitates more uniform distribution of inspired air compared to simpler unicameral lungs in some amphibians. Notably, in monitor lizards (Varanus spp.), through these multicameral lungs is unidirectional, resembling that in birds, where air moves in a single direction during both inspiration and expiration to optimize oxygen extraction. This pattern, demonstrated in species like the (Varanus exanthematicus), supports higher aerobic capacities in active foragers. Gas exchange in lizards occurs predominantly via the pulmonary route, with playing a minimal role due to their impermeable, scaly that limits across the skin. While some moisture-dependent species may exhibit trace cutaneous uptake, it contributes negligibly to overall oxygen needs, unlike in amphibians. During bursts of activity, lizards face elevated oxygen demands, prompting rapid increases in ventilation volume and frequency to sustain aerobic and prevent anaerobic reliance. Respiratory adaptations in lizards reflect ecological niches; for instance, semi-aquatic diving species like the water anole () employ bubble rebreathing, trapping an air bubble over the nostrils to rebreathe exhaled gases, which extends submersion times up to 16 minutes and aids buoyancy control by adjusting volume. Recent 2024 research on high-altitude lizards, such as Phrynocephalus vlangalii, reveals enhanced efficiency through increased organ mass and genetic selection for vascular remodeling, enabling better oxygen uptake in hypoxic environments.

Reproduction

Lizards exhibit diverse reproductive strategies, primarily , , and , adapted to various ecological niches. Most species are oviparous, laying eggs with leathery shells that are buried in or hidden in for incubation; for example, green iguanas (Iguana iguana) typically deposit clutches in humid burrows. In contrast, viviparous species, such as certain skinks in the genus Tiliqua, give birth to live young after internal embryonic development, often in colder climates where external incubation is challenging. Parthenogenesis, an asexual mode, occurs in all-female whiptail lizards (genus Aspidoscelis), where offspring develop from unfertilized eggs, enabling reproduction without males and contributing to rapid population expansion in isolated habitats. Mating behaviors in lizards often involve elaborate displays to attract partners and secure opportunities. Males may perform push-ups, head bobs, or extensions, as seen in anole lizards (genus ), to signal fitness and dominance; these visual cues are sometimes supplemented by chemical pheromones. Females of many species, including lacertids and geckos, possess sperm storage tubules in their reproductive tracts, allowing them to retain viable for months or even years, which facilitates delayed fertilization and multiple clutches from a single event. Clutch sizes vary widely among oviparous lizards, ranging from 1 to 50 eggs depending on species body size and environmental conditions; for instance, the common wall lizard () averages 4-8 eggs per clutch. In (TSD), prevalent in some families like and Scincidae, incubation temperatures influence offspring sex ratios—warmer conditions often produce females, while cooler ones yield males—providing an adaptive mechanism for population balance. Post-hatching, lizard life cycles feature independent hatchlings or live-born young that receive no , relying immediately on innate and antipredator instincts. Growth rates differ markedly by species and ; tropical lizards like geckos may reach maturity in 6-12 months, whereas temperate species such as the European common lizard (Zootoca vivipara) take 2-4 years due to seasonal constraints.

Aging

Lizards display considerable variation in lifespan across species, largely correlated with body size and environmental pressures. Small-bodied species, such as the (Uta stansburiana), typically survive only 1–2 years in the wild due to high metabolic rates and intense predation. In contrast, larger species like monitor lizards (Varanus spp.) achieve greater longevity, with individuals reaching up to 20 years in captivity and Komodo dragons (Varanus komodoensis) averaging about 30 years. Senescence in lizards involves progressive physiological decline, prominently marked by telomere shortening during and under from factors like elevated temperatures. This attrition accelerates aging processes and is evident in wild populations, where shorter telomeres correlate with increased mortality risk. Older lizards also exhibit reduced regenerative abilities, such as slower or less complete tail regrowth following , limiting their capacity for recovery from injury. Key factors shaping lizard aging include metabolic rate, which drives faster in small, high-energy species, and extrinsic threats like predation that curtail lifespan before intrinsic declines manifest. At higher elevations, shorter activity periods minimize metabolic wear and predation exposure, potentially extending . Some species may exhibit slow or , maintaining relatively stable mortality rates and physiological function into advanced age, though evidence remains limited. In female lizards, senescence often manifests as declining fertility, with telomere length predicting reductions in size and success over time.

Behavior

Thermoregulation and activity patterns

Lizards, as ectotherms, rely on external environmental sources to regulate their body rather than generating significant internal heat through . This dependence on ambient conditions necessitates precise behavioral adjustments to maintain optimal physiological function, as deviations can impair locomotion, , and . Behavioral thermoregulation in lizards primarily involves exploiting solar radiation and microhabitat variations. Individuals gain heat through basking on sun-exposed rocks or surfaces, often adopting flattened postures to maximize surface area absorption, while excess heat is dissipated by burrowing into cooler or seeking shaded refuges. Shuttling between sunlit and shaded areas allows fine-tuned control, with postural orientations—such as elevating the body to reduce ground contact—further modulating heat exchange. These strategies enable lizards to achieve a preferred body range typically between 30°C and 35°C, which supports peak metabolic performance across diverse . Activity patterns in lizards are closely tied to thermoregulatory needs, with most species exhibiting diurnal habits to capitalize on warmth for and movement. However, geckos represent a notable exception, being predominantly nocturnal to avoid daytime and predation while relying on nocturnal vision adaptations. In arid environments, some lizards adopt crepuscular patterns, active primarily at dawn and to minimize exposure to midday extremes while accessing milder temperatures for activity. Recent studies highlight how warming disrupts these patterns, pushing lizards toward thermal limits and reducing viable active hours. For instance, rising temperatures have restricted daily activity windows by up to 8% in temperate over the past two decades, as individuals spend more time in refuges to avoid overheating, thereby increasing energetic costs through elevated metabolic rates. In disturbed habitats, lizards experience body temperatures exceeding optimal ranges (e.g., above 36.8°C), leading to and shortened activity periods, particularly during summer peaks. These shifts underscore the vulnerability of ectothermic lizards to ongoing global warming, with recent research emphasizing the role of in preserving thermoregulatory opportunities and extending active times.

Territoriality and social structure

Most lizards exhibit solitary lifestyles, with individuals maintaining exclusive territories to minimize for resources such as , , and mates. This solitary predominates across the order , where stable social groups are rare and documented in only about 18 spanning seven families. Territoriality serves as the primary mechanism for spacing, often enforced through aggressive interactions that prevent overlap in home ranges. In contrast, some form temporary aggregations at resource hotspots, but these lack enduring bonds. Territorial displays are diverse and species-specific, commonly including visual signals like head-bobbing and movements to advertise ownership and deter intruders. For instance, in iguanid lizards such as Sceloporus occidentalis, displays function explicitly in territorial defense, with frequency correlating to encounter rates with rivals. Scent marking via cloacal secretions or femoral glands also plays a key role in boundary establishment, as observed in agamids and lacertids where chemical cues persist to signal presence over time. These displays are more pronounced in males, who typically hold larger, more defended territories than females, reflecting sex-based differences in resource needs and reproductive strategies. Dominance hierarchies emerge in species that form groups, particularly where dispersal is constrained, allowing subordinates to gain indirect benefits like protection. In rock agamas (), a dominant leads a of females and subordinate males, with stability maintained through ritualized threats and fights; victors display brighter coloration, such as orange heads, to reinforce status. Sex-based asymmetries are evident, as hierarchies often determine access, while females in groups like green iguanas (Iguana iguana) show less aggression and more tolerance. Colonial living occurs in select iguanas, such as marine iguanas (Amblyrhynchus cristatus), where groups of 20–500 individuals aggregate at basking sites, though internal territoriality persists among males. Cooperation is uncommon but documented in kin-based groups, notably communal egg-guarding in certain s. For example, in the five-lined (), females share nest duties in communal sites, alternating foraging and vigilance to enhance egg survival against predators. Similarly, species in the Egernia , like E. stokesii, form stable units where adults collectively defend nests, representing a rare shift from solitary territoriality toward familial .

Communication

Lizards employ a variety of communication modalities to convey information to conspecifics, primarily for courtship, alarm signaling, and social interactions such as territorial disputes. These include visual displays, chemical signals, acoustic vocalizations, and tactile contacts, often integrated in multimodal fashion to enhance efficacy in diverse environments. Visual communication is prevalent in diurnal lizards, relying on conspicuous body movements and coloration to signal intent. For instance, male anole lizards (genus Anolis) extend a colorful dewlap—a throat fan—during courtship to attract females or assert dominance, combining extension with head bobs for emphasis. Tail waving and flicks serve similar roles, as seen in collared lizards (Crotaphytus collaris), where lateral tail movements signal aggression or quality to rivals. Color changes, such as those in bearded dragons (Pogona vitticeps), further amplify signals by indicating arousal or status during social encounters. These displays are adjusted to environmental conditions, ensuring visibility in habitats like forests or open plains. Chemical communication involves pheromones secreted by specialized glands, facilitating long-distance or persistent signaling. Femoral glands on the hind limbs of many species, such as sand lizards (Lacerta agilis), produce lipid-rich secretions including and tocopherols that are deposited on substrates to mark territories or advertise presence. In , these pheromones convey genetic quality via (MHC) associations, influencing female in species like Sceloporus jarrovi. Alarm pheromones may also be released, though less studied, to warn conspecifics of threats. Secretions vary by individual and habitat, with urban populations showing greater chemical diversity. Acoustic signals are less common but prominent in certain lineages, particularly geckos, which vocalize using a modified . Male tokay geckos ( gecko) produce chirp sequences—such as the characteristic "tok-kay"—for territorial defense and , with frequencies around 2–5 kHz matching their auditory sensitivity. Distress calls, often single chirps, signal alarm during capture attempts. Some lizards employ substrate-borne vibrations, akin to foot-drumming, to communicate in low-visibility settings, though this is rarer than aerial sounds. Tactile communication occurs mainly during close-range interactions, emphasizing physical contact for or coordination. In mating contexts, males of various species nuzzle or gently touch females with their snouts or bodies to initiate , as observed in iguanids where such behaviors synchronize copulation. These signals complement other modalities, reducing ambiguity in dense vegetation or nocturnal settings. Recent studies highlight multimodal signaling in anoles, where visual extensions integrate with chemical cues and subtle vibrations to convey complex messages during and rival interactions, enhancing signal reliability across contexts. For example, brown anoles (Anolis sagrei) respond more strongly to combined visual and chemical signals from conspecifics than to single modalities. Such integration may reference territorial disputes briefly, amplifying displays to resolve conflicts efficiently.

Defense strategies

Lizards employ a variety of behavioral defense strategies to evade predators, focusing on deterrence, distraction, and escape without relying on morphological traits. These behaviors are often context-dependent, triggered by the proximity, speed, or type of threat, and can be combined for greater effectiveness. Bluffing tactics serve to intimidate potential attackers by exaggerating the lizard's size or ferocity. For instance, the frilled-neck lizard (Chlamydosaurus kingii) rapidly inflates a prominent while hissing loudly and opening its mouth wide, creating the illusion of a much larger and more aggressive opponent to discourage approach. Similarly, some species like the sailfin lizard (Hydrosaurus pustulatus) puff up their bodies and emit hissing sounds produced by forcing air through the , aiming to bluff predators into retreating without physical confrontation. Thanatosis, or feigning death, represents a passive bluffing strategy where lizards become limp and motionless to appear unpalatable or already deceased. This behavior is documented in multiple tropical species, including eight Amazonian lizards from families such as Gymnophthalmidae and (e.g., Microablepharus maximiliani and Kentropyx calcarata), which adopt a rigid posture with closed eyes and elevated limbs when restrained, reducing predator interest until the threat subsides. Thanatosis is particularly effective against visual hunters that prefer live prey, allowing the lizard to resume activity once safe. Flight responses emphasize rapid evasion, often involving high-speed sprints across open terrain. Many diurnal lizards, such as those in the Lacerta, achieve burst speeds exceeding 10 km/h to outrun pursuing predators like birds or mammals. To optimize escape, species like the Iberian wall lizard (Podarcis hispanicus) frequently flee tail-first, positioning the more dispensable tail toward the threat while protecting the vulnerable head and body; if grasped, the tail detaches via , wriggling independently to distract the predator and enable getaway. Chemical defenses provide a non-contact deterrent through the expulsion of noxious substances. Cloacal expulsion involves the release of malodorous from specialized glands, which can be sprayed or smeared onto attackers. In the black and white (Salvator merianae), this musking behavior is deployed during close encounters, combining with other tactics to repel predators via the repellent odor and taste. A more extreme form is reflex bleeding in horned lizards (Phrynosoma spp.), where ocular sinuses rupture to eject a stream of blood up to 2 meters, laced with foul-tasting chemicals that deter canines and other mammals by irritating their eyes or mouth. Immobility or freezing has emerged as a modified defense in human-altered environments. Urban lizards exhibit behavioral plasticity, with populations in urban areas showing adapted responses to frequent disturbances like human activity, indicating adjustments to novel threats.

Ecology

Distribution and habitats

Lizards exhibit a , inhabiting every continent except , where extreme precludes their survival. This widespread presence spans diverse biogeographic realms, from temperate zones to equatorial regions, facilitated by their ecological versatility and historical dispersal events. Species diversity is highest in , which supports over 850 lizard species across varied ecosystems, and in tropical regions globally, where environmental stability fosters and coexistence. Arid and forested , in particular, harbor the majority of the approximately 7,900 lizard species worldwide, as of September 2025, with nocturnal forms showing peak richness in these areas. Lizards occupy an array of habitats, adapting to extreme conditions from hyper-arid deserts to humid rainforests and even marine environments. In deserts, species like the (Phrynosoma spp.) thrive in sandy or rocky expanses of and beyond, relying on and minimal water needs. Rainforest dwellers, such as anoles (Anolis spp.) in Central and , navigate dense vegetation in the Neotropics, exploiting arboreal niches. Uniquely, the marine iguana (Amblyrhynchus cristatus) of the forages in coastal waters, representing one of the few truly marine lizards. Key adaptations enable lizards to persist in these specialized habitats. Marine species like the iguana possess nasal salt glands that excrete excess sodium chloride ingested from seawater, preventing osmotic imbalance through periodic "sneezing" of saline fluid. In arid zones, many lizards, including fringe-toed species (Uma spp.), have evolved burrowing behaviors and morphological traits such as fringed toes and streamlined bodies for efficient sand navigation, allowing escape from heat and predators while conserving moisture underground. These habitat-specific traits influence thermoregulation, as desert burrowers often emerge for basking in sun-exposed microhabitats. Habitat loss poses the primary threat to lizard populations, driven by , , and , which fragment ranges and degrade essential microenvironments. In forested habitats, 30% of lizard species face elevated risk from these pressures. Climate change exacerbates this, with models forecasting substantial climate-niche losses for many species in the Southwest, with some projected to lose up to 100% by late century under high-emission scenarios.

Diet and foraging

Lizards exhibit a range of dietary preferences, with the majority being insectivorous, primarily consuming arthropods such as , beetles, grasshoppers, and flies that provide essential nutrients and water. This feeding strategy is prevalent across small to medium-sized species, where insects form the bulk of the diet to support high metabolic demands. Less than 2% of lizard species are strictly herbivorous, though notable exceptions include iguanas like the (Iguana iguana), which rely on plant matter such as dark green leafy , fruits, and flowers for sustenance, often supplemented by specialized gut microbiomes to digest fibrous material. Carnivorous diets are observed in larger species, particularly monitor lizards (family ), which actively prey on vertebrates including small mammals, birds, eggs, , amphibians, and other reptiles, alongside invertebrates and carrion, reflecting their opportunistic and versatile feeding habits. Foraging behaviors in lizards vary significantly by species and , broadly categorized into sit-and-wait () and active modes. Sit-and-wait foragers, such as (Chamaeleonidae) and many iguanians, remain stationary for extended periods, relying on and sudden tongue strikes to capture passing prey within their , which conserves energy in environments with unpredictable prey movement. In contrast, active foragers like varanids (monitor lizards) patrol territories systematically, using keen senses of smell and sight to detect and pursue prey over distances, often incorporating climbing, digging, or swimming to access food sources, which suits open or structurally complex habitats. These modes influence energy expenditure and encounter rates, with active foragers typically covering more ground but risking higher predation exposure. Prey selection among lizards is often size-based, with individuals targeting items that align with their maximum gape width to maximize energy intake while minimizing handling time and risk of injury, as demonstrated in predators like the (Sceloporus undulatus). Opportunistic scavenging supplements live prey capture, particularly in omnivorous or stressed populations; for instance, even herbivorous species like the (Sauromalus obesus) have been observed consuming carrion when live food is scarce, providing a flexible fallback strategy. Recent research highlights how environmental pressures are altering these patterns: a 2025 study on invasive lizards (Anolis sagrei) in urban settings revealed dietary shifts toward broader foraging and reduced body condition due to declines linked to and , underscoring potential vulnerabilities for insect-dependent species.

Antipredator adaptations

Lizards have evolved a range of morphological and physiological traits to evade predation, primarily through concealment, , and deterrence. One key adaptation is via cryptic coloration and patterning, which allows individuals to blend seamlessly with their surroundings and avoid detection. For instance, species inhabiting sandy environments, such as certain South American sand lizards (e.g., Liolaemus lutzae and Liolaemus ardesiacus), exhibit blanched or pale dorsal coloration that matches white-sand substrates, reducing visibility to avian and mammalian predators; this adaptation has evolved repeatedly in isolated populations, driven by for . Similarly, island lizards like those on lilfordi in the show microhabitat-specific color matching, enhancing survival by minimizing contrast against local backgrounds. Another prominent antipredator trait is caudal autotomy, the voluntary shedding of the , which serves as a sacrificial to distract predators while escapes. The detached continues to twitch vigorously, often for several minutes, drawing attention away from the fleeing animal; this is particularly effective in species like the Mediterranean wall lizard (), where the tail's blue coloration in juveniles further deflects attacks. Tail regeneration follows, typically restoring functionality within weeks to months, though it incurs significant costs, including significant energetic expenditure, potentially constraining growth and reproduction, and reduced sprint speed or growth rates during the process. These trade-offs highlight the adaptation's evolutionary balance between immediate escape benefits and long-term fitness impacts. Additional physical defenses include specialized dermal structures that deter handling or consumption. The frilled lizard (Chlamydosaurus kingii) possesses a prominent neck frill—a fold of skin supported by cartilaginous rods—that can expand dramatically to over 30 cm in diameter, making the animal appear larger and more intimidating to approaching threats. Spiny scales provide passive armor in species like the thorny devil (Moloch horridus), whose body is covered in sharp, conical spines, rendering it unpalatable and difficult to swallow for predators such as goannas; these lizards also inflate their bodies with air to accentuate the spines' defensive role. Chemical defenses manifest in noxious secretions, notably in horned lizards (Phrynosoma spp.), which can forcibly eject blood from orbital sinuses containing toxic peptides derived from their ant-based diet; this autohaemorrhagic response repels canids and other predators by causing irritation or aversion, with the compounds (molecular weight 800-1,600 Da) persisting in the bloodstream due to dietary accumulation. Recent studies have illuminated variations in these traits across populations, particularly in insular environments. For example, 2024 research on the (Teira dugesii) in the reveals elevated tail bifurcation and regeneration rates in island populations, potentially linked to relaxed predation pressures that favor rapid recovery over perfect morphology, allowing quicker restoration of escape capabilities compared to mainland relatives.

Ecosystem interactions

Lizards occupy intermediate trophic levels in many ecosystems, functioning as predators of small invertebrates while serving as prey for higher-level carnivores. As voracious consumers of insects and arthropods, numerous lizard species contribute to pest population control; for instance, Anolis lizards have been documented to reduce herbivorous insect densities in agricultural and natural settings, thereby mitigating crop damage and supporting biodiversity. Concurrently, lizards themselves form a critical food source for avian and reptilian predators, such as birds of prey and snakes, which influences predator-prey dynamics and overall food web stability; studies on island ecosystems reveal that changes in lizard abundance can cascade through these interactions, altering community structure. Although uncommon compared to other vertebrates, certain lizards play niche roles in pollination and seed dispersal, particularly in insular or arid environments where traditional pollinators are scarce. On islands, species like geckos and skinks visit flowers for nectar, inadvertently transferring pollen and enhancing plant reproduction; for example, Balearic Island lizards interact with multiple plant species, acting as effective pollinators at the community level. Similarly, frugivorous lizards aid seed dispersal by consuming fruits and excreting viable seeds away from parent plants, with New Zealand geckos dispersing seeds up to 12 meters, promoting forest regeneration in isolated habitats. These interactions, while rare globally, underscore lizards' contributions to plant-animal mutualisms in specific biomes. Lizards serve as sensitive bioindicators of , reflecting changes in quality through population responses to and climatic shifts. Their ectothermic makes them vulnerable to contaminants like pesticides and , with species such as whiptail lizards accumulating toxins from and prey, signaling broader levels. Recent climate studies highlight their role in monitoring warming effects, projecting significant population declines in desert regions; for Gila monsters in the , models indicate contraction and reduced activity periods under extreme warming scenarios by mid-century, potentially leading to localized crashes due to prolonged droughts and heat stress. These sensitivities position lizards as early warning systems for anthropogenic environmental pressures. Symbiotic relationships involving lizards include both mutualistic and parasitic interactions that shape ecological balances. In some cases, indirectly benefit lizard reproduction by exploiting resources around nest sites, enhancing rates for like the long-tailed Mabuya through reduced predation or improved microhabitat conditions. Conversely, by is prevalent across lizard taxa, with ectoparasites such as Ophionyssus feeding on host blood and causing stress or disease transmission; in eastern collared lizards, mite loads vary by and correlate with host condition, influencing population health and dynamics.

Evolutionary History

Fossil record

The fossil record of lizards, as members of the order , begins in the Middle Triassic period, approximately 242 million years ago, with the discovery of Agriodontosaurus helsbypetrae from the Helsby Sandstone Formation in , . This specimen, a nearly complete of a small, insectivorous lepidosaur, represents the oldest known member of the group that includes lizards, snakes, and , predating previous records by 3 to 7 million years and providing key insights into early lepidosaur feeding adaptations, such as specialized jaw mechanics for processing hard-shelled prey. Earlier putative squamate relatives, like Megachirella wachtleri from the of (dated to ~242 million years ago), further support a origin for the lineage, filling a critical gap in the evolution of scaly reptiles and indicating that squamates arose shortly after the Permian-Triassic mass extinction. During the Era, squamate diversity expanded significantly through the and periods, with fossils documenting terrestrial, arboreal, and aquatic forms coexisting alongside dinosaurs. In the , marine adaptations reached their peak with mosasaurs, a group of large, predatory squamates that evolved paddle-like limbs and streamlined bodies, achieving global distribution as apex ocean hunters; phylogenetic analyses place mosasaurs within crown , often as basal members or close to anguimorph lizards, highlighting their role in early squamate ecomorphological experimentation. The period yielded fragmentary but informative remains, including the 2025 discovery of Breugnathair elgolensis from the Isle of Skye, —a (~167 million years old) lizard-like squamate with lizard proportions and limbs but snake-like jaws featuring hooked teeth for grasping prey, which challenges prior models of squamate evolution by suggesting mosaic anatomical transitions toward modern forms earlier than expected. The Cretaceous-Paleogene (K-Pg) boundary mass extinction event, ~66 million years ago, profoundly impacted squamates, causing an estimated 83% species-level extinction and eliminating many lineages, including most mosasaurs, alongside non-avian dinosaurs. However, surviving squamate clades, such as certain iguanians and scincomorphs, experienced only moderate long-term setbacks relative to other vertebrates, with fossil evidence from the showing rapid recovery and the beginnings of modern morphological diversity. A 2025 study further indicates that night lizards (family Xantusiidae) survived in proximity to the impact site in , likely due to their lifestyle and small clutch sizes of 1–2 offspring, representing a key example of localized survival among squamates. In the Era, particularly from the Eocene onward, squamates underwent a major radiation, diversifying into over 10,000 extant species across terrestrial, , and secondarily aquatic niches, driven by ecological opportunities following the K-Pg event and the spread of angiosperms. This post-Mesozoic proliferation is evidenced by abundant fossils from formations like the Green River Formation, underscoring squamates' resilience and adaptability in shaping contemporary reptile faunas.

Phylogenetic relationships

Lizards, as traditionally defined, form a paraphyletic group within the order , excluding snakes (Serpentes) and amphisbaenians (), which are nested within the broader squamate radiation. The major lizard clades—Iguania, Gekkota, , and —emerged through successive divergences, with Gekkota often positioned as the earliest-branching group among limbed lizards, followed by and the clade comprising Iguania, , and snakes. This structure reflects a origin for around 206 million years ago, with significant diversification during the , as reconstructed from molecular datasets including up to 12,896 base pairs across nuclear and mitochondrial genes. Molecular evidence strongly supports the monophyly of the Toxicofera clade, uniting venomous anguimorph lizards and snakes with non-venomous iguanians through shared toxin-secreting oral glands derived from ancestral mandibular structures. A 2024 proteomic analysis of mandibular glands in anguimorph species such as Abronia graminea and Abronia lythrochila identified kallikrein-like proteins and other bioactive compounds, confirming the presence of toxic secretions and reinforcing the single early origin of the venom system in Toxicofera estimated at approximately 170–200 million years ago. This aligns with genomic-scale studies using 91 squamate genomes, which report high posterior support for Toxicofera despite some locus-specific discordance in branch lengths. Cladograms derived from mitogenomic data illustrate the internal relationships within , highlighting basal anguimorphs such as Shinisauridae and as early-diverging lineages before the radiation of more derived groups like and Anguidae. For instance, phylogenetic trees show Shinisauridae (Shinisaurus crocodilurus) branching first, followed by (Gila monsters), with Anguidae and forming a subsequent sister clade that diverged around 112 million years ago. These topologies, calibrated using constraints, underscore the diversification of anguimorphs and their close affinity to serpentes within . Ongoing debates center on the precise position of Dibamidae (dibamids), a family of limbless, lizards, whose placement remains unstable across datasets. Post-2022 genomic analyses, incorporating long-read sequencing from 90+ squamate assemblies, variably position dibamids as the to all other squamates or clustering with Scincidae after Gekkota, challenging earlier views of them as basal to Bifurcata (all squamates except dibamids). Mitogenomic studies from 2024 further support dibamids diverging shortly after Gekkota, around 180–200 million years ago, but highlight long-branch attraction artifacts that may inflate their basal appearance. These discrepancies emphasize the need for additional high-quality dibamid genomes to resolve root-level squamate relationships.

Taxonomy

Lizards belong to the order within the class Reptilia, specifically the suborder (also known as ), which encompasses all squamate reptiles excluding snakes and amphisbaenians. This group includes approximately 38 families and over 7,900 valid , representing a significant portion of reptilian diversity. Notable families include , known as true lizards, which comprise about 400 of small, agile insectivores primarily in the , and , the monitor lizards, featuring large, predatory like the (Varanus komodoensis). These classifications are informed by phylogenetic relationships that group based on shared evolutionary ancestry. The nomenclature of lizards follows the Linnaean hierarchical system, utilizing for species and higher ranks such as , , and order to organize taxonomic diversity. Recent taxonomic revisions have refined this hierarchy through molecular and morphological analyses, leading to splits and recognitions of new ; for instance, in 2023, the extinct giant gecko Hoplodactylus delcourti was reclassified into its own , , based on phylogenetic evidence distinguishing it from other New Caledonian geckos. Such updates reflect ongoing efforts to align with evolutionary , ensuring monophyletic groupings where possible. Traditionally, lizards have been defined as a paraphyletic assemblage in , excluding snakes despite snakes having evolved from within lizard-like ancestors, thus rendering the group incomplete under cladistic principles that prioritize monophyletic . In cladistic frameworks, lizards are not a formal but are encompassed within alongside snakes, emphasizing shared traits like scaly skin and limbed bodies in most forms. This distinction highlights tensions between traditional morphological classifications and modern phylogenetic approaches. Taxonomic updates also incorporate conservation assessments from the International Union for Conservation of Nature (IUCN), which evaluates endangered lizard taxa; for example, approximately 20% of squamate , including many lizards such as those in the iguanid (with 73.8% threatened), are classified as vulnerable, endangered, or critically endangered due to habitat loss and other threats. These statuses guide protective measures for at-risk groups like island-endemic geckos and monitor lizards.

Adaptive convergence

Adaptive convergence in lizards refers to the independent evolution of similar morphological and physiological traits in distantly related lineages, often driven by analogous environmental pressures such as demands or predation risks. This is evident in various lizard groups, where unrelated species develop comparable adaptations to exploit similar ecological niches, highlighting the predictability of under consistent selective forces. A striking example of adaptive convergence involves gliding membranes, or patagia, which have evolved independently in the agamid genus Draco (flying dragons) and geckonid flying geckos (Ptychozoon species), despite their phylogenetic distance within Squamata. In Draco lizards from Southeast Asian forests, elongated ribs support expansive skin flaps that enable controlled glides of up to 60 meters between trees, facilitating escape from predators and access to resources in arboreal environments. Similarly, Ptychozoon geckos, adept wall-climbers, deploy cutaneous flaps along their sides, flanks, and tail for gliding descents, achieving comparable aerodynamic performance through convergent morphological innovations like enlarged dewlap-like structures. These parallel developments underscore the role of arboreal lifestyles in driving the repeated evolution of gliding capabilities across lizard lineages. Spiny tails represent another instance of convergence in multiple desert-dwelling lizard groups, including scincids, cordylids, and agamids, where unrelated have independently evolved enlarged, forming defensive caudal projections. This trait enhances survival in arid habitats by allowing individuals to wedge into crevices, deterring predators through mechanical resistance and potentially autotomizable deterrence. Biomechanical analyses reveal that spiny tails in these lineages confer similar advantages in locomotion over uneven substrates, with tail morphology correlating strongly with microhabitats rather than phylogenetic relatedness. Such convergence is attributed to shared selective pressures from predation and in ecosystems. In the realm of , s in the —encompassing anguimorph lizards, iguanian lizards, and snakes—exhibit molecular convergence through the shared recruitment and diversification of toxin-encoding genes, such as those for three-finger toxins and phospholipases A2, which have evolved similar neurotoxic and hemotoxic functions across lineages. Although originating from a common ancestral approximately 200 million years ago, these genes have undergone parallel structural modifications in distantly related members, like varanid lizards and elapid snakes, to produce functionally analogous cocktails tailored to prey subjugation. This genetic parallelism amplifies the efficacy of oral secretions in unrelated species facing comparable predatory challenges. Recent studies have further illuminated in cranial morphology, particularly shapes adapted to specific dietary niches. A analysis of over 300 lepidosaur demonstrated that mandibular forms in s have repeatedly converged on robust, durophagous structures in lineages exploiting hard-shelled prey, such as , independent of phylogenetic constraints. For instance, disparate iguanians and scincoids show parallel elongation and strengthening of the adductor musculature to handle tougher diets, with ecological factors like mode explaining up to 40% of shape variation. These findings emphasize how dietary selective pressures drive predictable morphological outcomes across lizard radiations.

Human Interactions

Uses and conservation

Lizards are utilized by humans in various ways, including as pets, food sources, materials for goods, and in biomedical research. Bearded dragons (Pogona vitticeps) are among the most popular lizard species kept as pets due to their docile nature and relatively straightforward care requirements. In some regions, particularly Central and , iguana meat serves as a protein source, valued for its nutritional profile similar to chicken and consumed in dishes like stews and curries. Lizard skins, especially from species like tegus ( spp.) and monitors, are harvested for high-end products such as belts, wallets, handbags, and watch straps, contributing to a multimillion-dollar exotic industry. Biomedically, venom from the (Heloderma suspectum) has led to the development of , a used in drugs like Byetta for treatment by mimicking to regulate blood sugar. Lizards face significant threats from human activities, including , , and the . Habitat loss due to , , and urban expansion is the primary driver of risk for over 20% of species, affecting lizards through fragmentation and degradation of essential microhabitats like rocky outcrops and arid scrublands. , such as feral cats and non-native s like Argentine tegus, prey on or compete with native lizards, exacerbating declines in hotspots like islands and grasslands. The international endangers thousands of lizard through overcollection and accidental releases that introduce invasives, with under-regulated markets threatening thousands of species; a 2025 study highlighted Canada's role in driving harmful trade, including monitors. further compounds these pressures, with 2025 modeling projecting that viability for certain , such as the Chilean lizard Liolaemus maldonadae, could decline by over 30% by 2100 due to shifting regimes and reduced suitable niches. Conservation efforts for lizards include international trade regulations, reintroduction programs, and the establishment of protected areas. The lists many lizards, such as the (Varanus komodoensis) in Appendix I, prohibiting commercial trade to prevent . Reintroduction initiatives have successfully bolstered populations of ; for example, programs in the UK have released approximately 9,000 sand lizards (Lacerta agilis) into restored heathlands since the , monitoring survival and breeding success. Protected areas play a crucial role by safeguarding habitats, with global networks covering key sites for reptiles. Recent studies on the underscore the urgency of habitat preservation amid global warming, projecting substantial range contractions in the by mid-century under high-emission scenarios, limited by the species' low dispersal and preference for cooler microhabitats.

Cultural significance

In various Native American cultures, particularly among Southwestern tribes like the and , lizards symbolize healing, , and renewal, often attributed to their to regenerate lost tails, which is interpreted as a for personal rebirth and . In contrast, some African folklore, especially among Zulu and Bantu communities, portrays lizards and chameleons as harbingers of misfortune or evil omens, stemming from myths where the chameleon's slow nature delayed a divine , leading to associations with and bad . Lizards feature prominently in Australian Aboriginal Dreamtime stories, where they embody ancestral beings and natural forces; for instance, tales like that of Lungkaṯa, the blue-tongued lizard man, explain geological formations at sites such as Uluṟu and highlight themes of survival and transformation. In , lizards are linked to deities and calendrical systems, with Macuilcuetzpalin—meaning "Five Lizard"—serving as a god of pleasure, dance, and excess, while the Lizard Trecena in the Tonalpohualli calendar underscores their role in divination and cosmic cycles. In art and media, lizards inspire representations of danger and exoticism, as seen in films like Komodo (1999), which depicts rampaging Komodo dragons as monstrous threats, and (2012), where they add tension to action sequences. Chameleons, meanwhile, frequently symbolize adaptability and change in literature, , and , such as in metaphorical uses in storytelling to represent shifting identities or environmental .

References

  1. https://opened.cuny.edu/courseware/lesson/756/overview
  2. http://www.reptile-database.org/db-info/SpeciesStat.html
  3. https://www.nps.gov/cabr/learn/nature/lizards.htm
  4. https://mdc.mo.gov/sites/default/files/2023-04/E00213%20A%20Guide%20to%20Missouri%27s%20Lizards.pdf
  5. https://www.bbc.com/news/world-africa-55945948
  6. https://nationalzoo.si.edu/animals/komodo-dragon
  7. http://www.zo.utexas.edu/faculty/pianka/Lizard_Natural_History.html
  8. https://pmc.ncbi.nlm.nih.gov/articles/PMC10251849/
  9. https://onlinelibrary.wiley.com/doi/10.1111/j.1466-8238.2011.00700.x
  10. https://www.usgs.gov/media/videos/gila-monster
  11. https://www.nationalgeographic.com/animals/reptiles/facts/komodo-dragon
  12. https://www.honoluluzoo.org/animals/crocodile-monitor-lizard/
  13. https://www.newscientist.com/article/dn1635-minute-gecko-matches-smallest-reptile-record/
  14. https://www.nature.com/articles/s41598-020-80955-1
  15. https://www.semanticscholar.org/paper/Evolution-and-ecology-of-lizard-body-sizes-Meiri/72fba558be9d6ee1ace2e475586a090f95c8ce6a
  16. https://pmc.ncbi.nlm.nih.gov/articles/PMC10320661/
  17. https://pmc.ncbi.nlm.nih.gov/articles/PMC11366495/
  18. https://www.researchgate.net/publication/331722272_Reptilian_Skin_and_Its_Special_Histological_Structures
  19. https://pmc.ncbi.nlm.nih.gov/articles/PMC9292694/
  20. https://pmc.ncbi.nlm.nih.gov/articles/PMC10161005/
  21. https://www.researchgate.net/publication/331815887_Squamate_Morphology
  22. https://www.biorxiv.org/content/10.1101/2020.08.21.260596v1.full.pdf
  23. https://www.researchgate.net/publication/227651815_How_lizards_turn_into_snakes_A_phylogenetic_analysis_of_body-form_evolution_in_anguid_lizards
  24. https://www.degruyterbrill.com/document/doi/10.1515/9783110367256-003/html
  25. https://pmc.ncbi.nlm.nih.gov/articles/PMC7333653/
  26. https://pmc.ncbi.nlm.nih.gov/articles/PMC3497141/
  27. https://pmc.ncbi.nlm.nih.gov/articles/PMC10333127/
  28. https://www.merckvetmanual.com/all-other-pets/reptiles/description-and-physical-characteristics-of-reptiles
  29. https://mcb.berkeley.edu/courses/bio1a/lab/downloads/Bio1AL_Diveristy_Amphibia%2BReptilia.pdf
  30. https://www.pnas.org/doi/10.1073/pnas.0405736101
  31. https://www.pnas.org/doi/10.1073/pnas.0608841103
  32. https://www.nature.com/articles/s41598-020-79113-4
  33. https://www.journals.uchicago.edu/doi/pdfplus/10.1086/673864
  34. http://reptilis.net/lacertilia/varanidae/moving.html
  35. https://royalsocietypublishing.org/doi/10.1098/rsif.2018.0276
  36. https://www.jstor.org/stable/1447696
  37. https://journals.biologists.com/jeb/article/217/16/2899/13794/Ultraviolet-vision-in-lacertid-lizards-evidence
  38. https://www.nature.com/articles/s41598-019-50712-0
  39. https://www.frontiersin.org/journals/amphibian-and-reptile-science/articles/10.3389/famrs.2024.1426675/full
  40. https://www.researchgate.net/publication/261571079_The_Function_of_Jacobson%27s_Organ_in_Lizards
  41. https://www.sciencedirect.com/science/article/abs/pii/S000334720580380X
  42. https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1439-0310.1979.tb00672.x
  43. https://pmc.ncbi.nlm.nih.gov/articles/PMC6003244/
  44. https://www.anapsid.org/reptilehearing.html
  45. https://www.frontiersin.org/journals/amphibian-and-reptile-science/articles/10.3389/famrs.2024.1429172/full
  46. https://www.snexplores.org/article/gecko-night-vision
  47. https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=174112
  48. https://www.sciencedirect.com/science/article/abs/pii/S108060329770022X
  49. https://pubmed.ncbi.nlm.nih.gov/16292255/
  50. https://pubmed.ncbi.nlm.nih.gov/6789871/
  51. https://pubmed.ncbi.nlm.nih.gov/25603280/
  52. https://pubmed.ncbi.nlm.nih.gov/16321550/
  53. https://www.nature.com/articles/ncomms2065
  54. https://www.sciencedirect.com/science/article/abs/pii/S0041010110004472
  55. https://pmc.ncbi.nlm.nih.gov/articles/PMC7082849/
  56. https://academic.oup.com/book/36519/chapter/321266922
  57. https://pmc.ncbi.nlm.nih.gov/articles/PMC8174041/
  58. https://pubmed.ncbi.nlm.nih.gov/15961533/
  59. https://www.sciencedirect.com/science/article/abs/pii/S0944200623000120
  60. https://pubmed.ncbi.nlm.nih.gov/24336209/
  61. https://www.sciencedirect.com/science/article/am/pii/S0944200615000549
  62. https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Introductory_Biology_%28CK-12%29/12%253A_Vertebrates/12.16%253A_Reptile_Structure_and_Function
  63. https://pubmed.ncbi.nlm.nih.gov/7280383/
  64. https://www.sciencedirect.com/science/article/pii/S0960982221005753
  65. https://www.sciencedirect.com/science/article/abs/pii/S1095643323000594
  66. https://pmc.ncbi.nlm.nih.gov/articles/PMC11790214/
  67. https://www.nps.gov/bibe/learn/nature/big-bend-lizards.htm
  68. https://nationalzoo.si.edu/animals/crocodile-monitor
  69. https://www.nature.com/articles/s41598-017-17323-z
  70. https://pmc.ncbi.nlm.nih.gov/articles/PMC9388115/
  71. https://pmc.ncbi.nlm.nih.gov/articles/PMC6085768/
  72. https://pmc.ncbi.nlm.nih.gov/articles/PMC10099801/
  73. https://pmc.ncbi.nlm.nih.gov/articles/PMC7485750/
  74. https://onlinelibrary.wiley.com/doi/10.1111/mec.16981
  75. https://www.nature.com/articles/s41598-024-69378-4
  76. https://www.sciencedirect.com/science/article/abs/pii/S0306456517305302
  77. https://www.researchgate.net/publication/325387288_The_impact_of_posture_and_basking_orientation_on_thermoregulation_in_the_Sungazer_Smaug_giganteus
  78. https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/1365-2435.14192
  79. https://academic.oup.com/biolinnean/article/115/4/896/2440166
  80. https://www.desertmuseum.org/books/nhsd_adaptations_amph.php
  81. http://www.zo.utexas.edu/faculty/pianka/lacertids.html
  82. https://www.nature.com/articles/s41598-023-35087-7
  83. https://www.nature.com/articles/s41598-024-83845-y
  84. https://www.sciencedirect.com/science/article/pii/S0006320725005622
  85. https://pmc.ncbi.nlm.nih.gov/articles/PMC12044374/
  86. https://dash.harvard.edu/bitstreams/be54fb41-7717-459b-94c5-aa3ef5a30665/download
  87. https://www.nature.com/articles/s41598-025-90393-6
  88. https://pmc.ncbi.nlm.nih.gov/articles/PMC9000839/
  89. https://www.researchgate.net/publication/275639411_Pheromones_and_Chemical_Communication_in_Lizards
  90. https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.24553
  91. https://www.jstor.org/stable/3884559
  92. https://publish.iupress.indiana.edu/read/how-animals-communicate/section/acea8595-e703-4b66-9da3-d83b9c5df064
  93. https://pmc.ncbi.nlm.nih.gov/articles/PMC8614464/
  94. https://academic.oup.com/cz/article/58/6/791/1845064
  95. https://onlinelibrary.wiley.com/doi/abs/10.1111/eth.13402
  96. https://www.nationalgeographic.com/animals/article/151024-animal-behavior-lizards-reptiles-geckos-science-anatomy
  97. https://www.researchgate.net/publication/245022602_Hissing_Sounds_by_the_Lizard_Pristidactylus_volcanensis
  98. https://besjournals.onlinelibrary.wiley.com/doi/10.1046/j.1365-2435.1998.00247.x
  99. https://revchilhistnat.biomedcentral.com/articles/10.1186/s40693-014-0010-6
  100. https://pmc.ncbi.nlm.nih.gov/articles/PMC11135363/
  101. https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=3776&context=icwdm_usdanwrc
  102. https://royalsocietypublishing.org/doi/10.1098/rsbl.2025.0326
  103. https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/squamate
  104. https://www.nature.com/articles/s41598-020-74867-3
  105. http://www.gardinitiative.org/blogard/category/tropics
  106. https://worldostats.com/country-stats/lizard-population-by-country/
  107. https://www.nature.com/articles/s41586-022-04664-7
  108. https://journals.physiology.org/doi/abs/10.1152/ajplegacy.1969.216.4.995
  109. https://onlinelibrary.wiley.com/doi/full/10.1002/ece3.70379
  110. https://ww2.jacksonms.gov/Resources/EFIcUt/274026/what_is_a_lizard.pdf
  111. https://pmc.ncbi.nlm.nih.gov/articles/PMC9175459/
  112. https://digitalcommons.wku.edu/theses/392/
  113. https://repository.si.edu/server/api/core/bitstreams/5202b189-7e1d-403d-8719-c4741e7f178c/content
  114. https://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=1085
  115. https://crocdoc.ifas.ufl.edu/publications/articles/Mazzottietal2020.pdf
  116. http://www2.hawaii.edu/~mbutler/PDFs/Butler05.pdf
  117. https://www.britannica.com/animal/lizard/Scales-and-colour-change
  118. http://www.zo.utexas.edu/courses/THOC/ForagingTactics.html
  119. https://journal-of-herpetology.kglmeridian.com/downloadpdf/view/journals/hpet/53/1/article-p32.xml
  120. https://www.sciencedirect.com/science/article/abs/pii/S0140196311000590
  121. https://link.springer.com/article/10.1007/s11252-025-01722-6
  122. https://onlinelibrary.wiley.com/doi/full/10.1002/ece3.9555
  123. https://www.nature.com/articles/srep19815
  124. https://zslpublications.onlinelibrary.wiley.com/doi/abs/10.1111/jzo.12361
  125. https://pmc.ncbi.nlm.nih.gov/articles/PMC8709428/
  126. https://academic.oup.com/beheco/article/17/5/857/207107
  127. https://www.researchgate.net/publication/344665845_Uncovering_the_function_of_an_enigmatic_display_antipredator_behaviour_in_the_iconic_Australian_frillneck_lizard
  128. https://animaldiversity.org/accounts/Moloch_horridus/
  129. https://www.researchgate.net/publication/386812696_Insights_into_tail_bifurcation_and_regeneration_rates_in_the_Madeira_wall_lizard_Teira_dugesii_from_Azores
  130. https://pmc.ncbi.nlm.nih.gov/articles/PMC5383488/
  131. https://www.princeton.edu/news/2019/06/10/how-do-new-predators-change-ecosystem-watch-prey-say-princeton-researchers
  132. https://pmc.ncbi.nlm.nih.gov/articles/PMC10044671/
  133. https://www.tandfonline.com/doi/full/10.1080/03036758.2015.1108924
  134. https://www.sciencedirect.com/science/article/abs/pii/S0169534703000041
  135. https://pubmed.ncbi.nlm.nih.gov/32583019/
  136. https://phys.org/news/2025-04-gila-monsters-struggle-survive-planet.html
  137. https://www.researchgate.net/publication/227719777_Resources_exploitation_by_ants_facilitates_lizard_egg_survival
  138. https://bioone.org/journals/the-southwestern-naturalist/volume-67/issue-4/0038-4909-67.4.291/CHARACTERIZATION-OF-MITE-PARASITISM-OF-EASTERN-COLLARED-LIZARDS-CROTAPHYTUS-COLLARIS/10.1894/0038-4909-67.4.291.full
  139. https://www.nature.com/articles/s41586-025-09496-9
  140. https://www.nature.com/articles/s41586-018-0093-3
  141. https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2019.00047/full
  142. https://www.nature.com/articles/s41586-025-09566-y
  143. https://www.pnas.org/doi/10.1073/pnas.1211526110
  144. https://royalsocietypublishing.org/doi/10.1098/rsbl.2025.0157
  145. https://www.nature.com/articles/s41467-022-34217-5
  146. https://bmcecolevol.biomedcentral.com/articles/10.1186/1471-2148-13-93
  147. https://pmc.ncbi.nlm.nih.gov/articles/PMC11312734/
  148. https://www.researchgate.net/publication/382834208_Mandibular_gland_proteomics_of_the_Mexican_alligator_lizard_Abronia_graminea_and_the_red-lipped_arboreal_alligator_lizard_Abronia_lythrochila
  149. https://www.mdpi.com/2073-4425/14/7/1387
  150. https://www.repfocus.dk/BIO/FAM_ORDER_CLASS/Reptilia_biodiversity_01.html
  151. https://www.nature.com/articles/s41598-023-35210-8
  152. https://www.iucnredlist.org/resources/coxetal2023
  153. https://www.pnas.org/doi/10.1073/pnas.2024451118
  154. https://www.ross.aoe.vt.edu/papers/khandelwal-ross-dong-socha-2023.pdf
  155. https://allyouneedisbiology.wordpress.com/2015/08/24/gliding-amphibians-reptiles/
  156. https://pmc.ncbi.nlm.nih.gov/articles/PMC7058953/
  157. https://www.pnas.org/doi/10.1073/pnas.0810883106
  158. https://royalsocietypublishing.org/doi/10.1098/rspb.2024.2052
  159. https://www.frontiersin.org/journals/ecology-and-evolution/articles/10.3389/fevo.2024.1361799/full
  160. https://vcahospitals.com/know-your-pet/bearded-dragons-owning
  161. https://blogs.ifas.ufl.edu/news/2019/08/21/considering-iguana-meat-as-protein-consider-food-safety-first/
  162. https://portals.iucn.org/library/sites/library/files/documents/Traf-013.pdf
  163. https://pmc.ncbi.nlm.nih.gov/articles/PMC8491154/
  164. https://academic.oup.com/bioscience/article/50/8/653/243214
  165. https://www.nature.com/articles/s41467-020-18523-4
  166. https://biologicaldiversity.org/w/news/press-releases/new-study-highlights-canadas-role-in-driving-harmful-reptile-trade-2025-10-16/
  167. https://cites.org/eng/taxonomy/term/4181
  168. https://www.arc-trust.org/saving-sand-lizard
  169. https://www.nature.com/articles/s41467-023-36987-y
  170. https://pmc.ncbi.nlm.nih.gov/articles/PMC11913548/
  171. https://blog.kachinahouse.com/the-lizard-in-native-american-culture/
  172. https://www.native-languages.org/legends-lizard.htm
  173. https://www.chameleons.info/l/the-superstitious-chameleon/
  174. https://simvers.com/lizard-symbolism-dream-mythology/
  175. https://uluru.gov.au/discover/culture/stories/lungkata-story/
  176. https://www.godchecker.com/aztec-mythology/MACUILCUETZPALIN/
  177. https://richardbalthazar.com/2023/08/30/aztec-calendar-lizard-trecena/
  178. https://www.imdb.com/title/tt0172669/
  179. https://www.youtube.com/watch?v=28-7j8dnUAw
  180. https://blogs.timesofisrael.com/photo-essay-chameleons-the-art-of-change/
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