Home>>All Animals>>Reptilia>>Squamata

Squamata

Squamata is the largest order of reptiles, with about 6,000 species, accounting for more than 90% of existing reptiles. It is divided into two orders, including the lizards and snakes. The body surface is covered with keratinous scales, generally without bony plates, and the body is mostly long. The front and rear limbs are well developed or degenerate.

I. Introduction to Squamata

1. Definition and Key Characteristics

  • Taxonomic Placement
    Squamata is the largest order of Reptilia (reptiles), comprising all lizards (in a broad sense), snakes, and amphisbaenians (worm lizards). With over 10,000 described species, they inhabit a range of environments (deserts, rainforests, grasslands, coastlines, etc.) worldwide, excluding the polar regions.

  • Morphological and Physiological Traits

    • Scaled Skin: Squamates have keratinized scales that reduce water loss and provide protection. Many species shed these scales periodically during growth.

    • Flexible Jaws: Most squamates have a relatively kinetic skull and jaw articulation; notably, snakes can disarticulate their jaws extensively to swallow large prey.

    • Locomotion Variations: Lizards typically have four limbs (though some groups like glass lizards have reduced limbs). Snakes have lost limbs entirely and move by lateral undulation or other specialized methods. Amphisbaenians (worm lizards) also lack visible limbs, with segmented bodies adapted to burrowing.

  • Lifestyle Diversity

    • Diet: Ranges from strict herbivory (e.g., iguanas) and insectivory to carnivory (e.g., large constrictors, venomous snakes) or specialized feeding.

    • Reproduction: Most are oviparous (egg-laying), though some exhibit ovoviviparity or viviparity (e.g., some vipers and skinks).

2. Ecological and Human Relevance

  • Role in Food Webs
    Many lizards and snakes act as medium-level predators, controlling insect or rodent populations, and serving as prey for birds or larger carnivores. Herbivorous lizards may help in seed dispersal and plant community dynamics.

  • Economic and Cultural Value

    • Pest Control and Balance: Snakes can significantly reduce rodent populations in agricultural areas.

    • Medicinal and Ornamental: Some snakes (e.g., cobras, pit vipers) are used in traditional medicine, while various lizards (e.g., green iguana) and snakes (e.g., ball pythons, kingsnakes) are popular in the pet trade.

    • Negative Impacts: A few venomous species pose safety risks; some introduced lizards (e.g., green iguanas) can become invasive in non-native regions.


II. Evolutionary History

  1. Origins and Early Evolution

  • Squamates trace back to Jurassic–Cretaceous ancestors (~150–100 million years ago). They derived from older diapsid reptiles, diversifying widely through the Mesozoic era.

  • Snakes (Serpentes) evolved from a particular lineage of limbless or limb-reduced lizards, though whether this occurred primarily in a burrowing terrestrial environment or a marine environment was long debated. Current evidence favors a terrestrial or fossorial (burrowing) origin.

  1. Modern Diversification and Global Spread

  • Geological and climatic changes (e.g., continental drifts, sea-level changes) from the Cretaceous onward allowed lizards and snakes to expand nearly worldwide, except the coldest polar areas.

  • Different groups have successfully adapted to terrestrial, arboreal, fossorial, freshwater, or even marine environments (such as marine iguanas or sea snakes).


III. Major Classification Table of Squamata

Traditionally, lizards (Lacertilia / Sauria), snakes (Serpentes), and amphisbaenians (Amphisbaenia) are recognized as three major lineages. Below is a concise list of prominent families and representative genera. Please note that molecular research continues to refine family-level boundaries.

A. Lizards (Broadly, “Lacertilia/Sauria”)

FamilyRepresentative GeneraExample SpeciesDistribution & Notes
Gekkonidae (Geckos)Gekko (Tokay gecko), Hemidactylus (House gecko), etc.Tokay gecko (Gekko gecko), Common house gecko (Hemidactylus frenatus), etc.Typically small, nocturnal lizards with adhesive toe pads for climbing walls and ceilings.
Scincidae (Skinks)Eumeces (Skinks), Scincus (Sand skinks), etc.Blue-tailed skink (Plestiodon/ Eumeces laticeps), etc.Many have cylindrical bodies and smooth scales; some exhibit limb reduction or viviparity.
Agamidae (Agamas)Pogona (Bearded dragons), Draco (Flying dragons), etc.Central bearded dragon (Pogona vitticeps), Flying lizard (Draco volans), etc.Found in Africa, Asia, and Australia; popular as pets (bearded dragons); Draco can glide among trees.
Chamaeleonidae (Chameleons)Chamaeleo, Furcifer, Calumma, etc.Panther chameleon (Furcifer pardalis), Veiled chameleon (Chamaeleo calyptratus), etc.Africa & Madagascar primarily; famous for projectile tongues, independently rotating eyes, vivid coloration.
Iguanidae (Iguanas)Iguana, Amblyrhynchus (Marine iguana), etc.Green iguana (Iguana iguana), Galápagos marine iguana (Amblyrhynchus cristatus), etc.Mostly New World; some species herbivorous (e.g., green iguana), others specialized (marine iguana dives for algae).
Helodermatidae (Beaded lizards)Heloderma (Gila monster, Beaded lizard)Gila monster (Heloderma suspectum), Mexican beaded lizard (H. horridum)North American desert dwellers; possess venomous glands, injecting toxin via grooved teeth.
Varanidae (Monitor lizards)Varanus (Monitors)Komodo dragon (Varanus komodoensis), Asian water monitor (Varanus salvator), etc.Africa, Asia, Oceania distribution; often large-bodied; Komodo dragon is among the world’s largest lizards.

B. Snakes (Serpentes)

FamilyRepresentative GeneraExample SpeciesDistribution & Notes
Pythonidae (Pythons)Python, Morelia, Liasis, etc.Burmese python (Python bivittatus), Reticulated python (Malayopython reticulatus), etc.Old World distribution, typically large constrictors; some can exceed 6 meters in length.
Boidae (Boas & Anacondas)Boa, Eunectes, etc.Boa constrictor (Boa constrictor), Green anaconda (Eunectes murinus), etc.New World distribution, parallel to pythons in function (constrictors); anacondas among the heaviest snakes.
Colubridae (Typical snakes)Natrix (Grass/Water snakes), Elaphe (Ratsnakes), Pantherophis, etc.Grass snake (Natrix natrix), King ratsnake (Elaphe carinata), etc.The largest snake family worldwide; most are non-venomous or only mildly venomous; highly diverse ecologically.
Elapidae (Cobras, Kraits, Mambas, Coral snakes, etc.)Naja (Cobra), Ophiophagus (King cobra), Micrurus (Coral snakes), etc.King cobra (Ophiophagus hannah), Indian cobra (Naja naja), etc.Possess potent neurotoxic venom, found in Africa, Asia, Australia, and the Americas (e.g., coral snakes).
Viperidae (Vipers & Pit vipers)Vipera, Crotalus (Rattlesnakes), Bothrops (Lanceheads), etc.Timber rattlesnake (Crotalus horridus), Gaboon viper (Bitis gabonica), etc.Venomous snakes with cytotoxic or hemotoxic venom; common morphological traits include triangular heads and vertical pupils.
(Sea Snakes: Subfamily Hydrophiinae under Elapidae)Hydrophis, Laticauda, etc.Banded sea krait (Laticauda colubrina), Short-headed sea snake (Hydrophis curtus), etc.Fully or partially marine, primarily in Indo-Pacific warm seas; often highly venomous.

C. Amphisbaenians (Worm Lizards)

FamilyRepresentative GeneraExample SpeciesDistribution & Notes
AmphisbaenidaeAmphisbaena, Zygaspis, etc.Various “worm lizards” (Amphisbaena alba, etc.)Africa and the Americas; elongate and limbless, adapted for fossorial (burrowing) life with a reinforced skull.
TrogonophidaeTrogonophis, Parea, etc.Moroccan worm lizard (Trogonophis wiegmanni), etc.Found in North Africa/Middle East; ringed body segments, head-tail similarity for burrowing.
BipedidaeBipes (Two-legged worm lizards)Mexican mole lizard (Bipes biporus), etc.Endemic to arid regions of Mexico, unique among amphisbaenians in retaining forelimbs but no hind limbs.

(Note: The amphisbaenian suborder is less commonly encountered but evolutionarily significant.)


IV. Conclusion

  1. Multiple Adaptations and Global Distribution

  • Squamata represents over 95% of extant reptile species. Fossil and molecular data indicate they underwent major diversification from the Late Jurassic to the Cretaceous, dispersing via land bridges and sea-level changes to inhabit most warm regions worldwide.

  1. Ecological and Human Interactions

  • Squamates often occupy mid-level trophic positions, helping maintain ecological balance (e.g., snakes controlling rodents).

  • Some species are harvested for food or traditional medicine, while others are valuable in the pet trade. However, invasive species introductions, potential venomous risks, and habitat encroachment are ongoing concerns.

  1. Conservation Challenges

  • Habitat loss, pollution, overharvesting, and climate change imperil many squamate species (e.g., island-endemic lizards, rare vipers).

  • Legislation, education, regulated pet trade, and habitat conservation are crucial for preserving squamate diversity and ecological stability.


Summary

This overview provides a brief introduction to the history of the order Squamata, its major classifications, and its role in ecology and human society. For more in-depth species-level or regional information, refer to professional herpetology books, field manuals, and the latest molecular systematics papers. I hope that this "Squamata Classification" will provide you with detailed and easy-to-understand scientific information to help readers understand the fascinating world of the three major groups of reptiles: lizards, snakes, and caecilians.

Testudines Squamata Crocodilia Lizardia
Dopasia

Dopasia

Dopasia,Hart's glass lizard,Golden snake, Venus ground eel, broken snake, snake lizard, earth dragon

Features:The cloaca emits a special odor

The English name of the brittle lizard is Hart's glass lizard, and there is no subspecies.In mid-to-late October, when the temperature drops to around 13℃, the brittle lizards gradually enter hibernation. When the temperature drops below 8℃, they enter deep sleep. Females and young lizards hib...

Ophisaurus hainanensis

Ophisaurus hainanensis

Ophisaurus hainanensis,Hainan glass lizard

Features:The ear holes are extremely small and needle-like

Foreign name Hainan glass lizard, a species endemic to China. Listed in the "National List of Terrestrial Wildlife with Important Economic and Scientific Research Values Protected by the State" issued by the State Forestry Administration of China on August 1, 2000.Listed in the 2013 Red Li...

Ophisaurus gracilis

Ophisaurus gracilis

Ophisaurus gracilis,Ground eel, tin snake, thin snake lizard, Yunnan snake lizard

Features:A limbless lizard that resembles a snake

Burmeseglass snake (Daniel) is a lizard without limbs and looks like a snake. The significant differences in appearance from snakes include: the abdominal scales are not wide and short scales, but have multiple rows of scales similar to the dorsal scales.The brittle snake lizard often goes out to fo...

Physignathus cocincinus

Physignathus cocincinus

Physignathus cocincinus,Long rock agama,Water Dragon

Features:Good at swimming and tree climbing

Long rock agama, no subspecies.Long rock agama lives on bamboo branches near rivers and ditches with trees and rocks, in the forest or on sandy land. They are good at climbing trees, and live mostly on the trunks of old and large trees, in the cool grass near water, between trees, and in the cracks...

Phrynocephalus mystaceus

Phrynocephalus mystaceus

Phrynocephalus mystaceus,Toad-headed Agama

Features:The largest species of lizard

The big-eared sand lizard is called Toad-headed Agama in English, and there are 2 subspecies.The big-eared sand lizard runs very fast, and when it encounters danger, it quickly burrows into the sand dunes and disappears. When being chased, it often keeps its body swaying close to the ground, digging...

Phrynocephalus guinanensis

Phrynocephalus guinanensis

Phrynocephalus guinanensis,Guinan Toad-headed Lizard

Features:Often lie down at the entrance of the cave to bask in the sun at noon

Guinan Toad-headed Lizard is an ovoviviparous lizard.Guinan Toad-headed Lizard lives in caves, usually on the slopes of hardened gravel, sand dunes and earth ridges, and some are under gravel. The cross-section of the cave entrance and tunnel is half-moon-shaped, and the size varies with the size of...

Leiolepis reevesi

Leiolepis reevesi

Leiolepis reevesi,Reeves' butterflylizard,Mountain horse, salon, Polon

Features:They live in groups, one lizard per cave

The foreign name of the wax lizard is Reeves' butterflylizard, and there is no subspecies.The species name of the waxy lizard is reevesii, named after the naturalist and collector John Reeves (1774-1856), who sent specimens of the waxy lizard back to England. Reeves was employed by the East Indi...

Diploderma makii

Diploderma makii

Diploderma makii,Makijapalure,Mu's climbing lizard

Features:Tail length about twice as long as head and body

The Xitou dragon lizard is called Makijapalure in foreign language, and has no subspecies.The Xitou dragon lizard is a tree-dwelling creature, diurnal, often active in the open space at the edge of the forest during the day, and often on the leaves facing the light in the bushes. It is highly territ...

Diploderma batangense

Diploderma batangense

Diploderma batangense,Jpalura batangensis,Batang climbing lizard, fast-walking lizard

Features:Ability to run quickly and change direction quickly,It lives on the rocks on the hillsides at an altitude of 2500 to 3400 meters. It is active during the day and feeds mainly on small spiders and insects.

The foreign name of the Batang dragon lizard is Jpalura batangensis. It mainly chooses to overwinter in places such as rock crevices and dead branches and leaves.The Batang dragon lizard feeds on insects and some rodents, and occasionally poultry. Its teeth are sharp and have three cusps. Herbivores...

Goniurosaurus zhoui

Goniurosaurus zhoui

Goniurosauruszhoui,Zhou’s Leopard Gecko

Features:This is the third species of the genus Gecko found in Hainan.

Zhou’s Leopard Gecko is the third species of gecko found in Hainan. It is also the first species of gecko found independently by a Chinese on Hainan Island. The discoverer is Zhou Runbang of the Hainan Provincial Forestry Department.Zhou’s Leopard Gecko was found in the central part of Hainan Isla...

Goniurosaurus luii

Goniurosaurus luii

Goniurosaurus luii

Features:It is a beautifully colored reptile.

Pingxiang eyelid gecko was discovered in 1999 and is native to Guangxi.Pingxiang eyelid gecko is a nocturnal animal. It hides in the cracks of rocks during the day. When the sun sets, it comes out to move around, wandering among the rocks, and preying on insects and other small invertebrates.The pop...

Goniurosaurus kwangsiensis

Goniurosaurus kwangsiensis

Goniurosaurus kwangsiensis,aekezrin(噁呃碄),

Features:A new species of gecko discovered in recent years

Guangxi eyelid gecko, scientific name Goniurosaurus kwangsiensis, is a newly discovered eyelid gecko in China in recent years.In June 2015, Kadoorie Conservation China published a new species of Guangxi eyelid gecko in the international animal taxonomy journal "ZOOTAXA". Since this is a ne...

Goniurosaurus bawanglingensis

Goniurosaurus bawanglingensis

Goniurosaurus bawanglingensis,Bawangling Leopard Gecko,Chinese Tiger Gecko,

Features:It is a species unique to Hainan, China.

Bawangling Leopard Gecko is a species unique to Hainan.At around 9 p.m. on July 5, 2001, specimen collectors were waiting for nocturnal animals in the jungle of Bawangling. The flashlight illuminated a 10-centimeter-long gecko (Gecko), which was very different from the geckos they had seen in the pa...

Goniurosaurus yingdeensis

Goniurosaurus yingdeensis

Goniurosaurus yingdeensis,Yingde Leopard Gecko,Eyelid gecko,Goniurosaurus yingdeensis WANG, YANG & CUI

Features:Endemic to China

Yingde Leopard Gecko is a species endemic to my country.In the stone-covered karst jungle of Yingde City, Guangdong Province, a small gecko-like reptile attracts many reptile enthusiasts and researchers because of its bright surface. This is the "colorful version of the gecko", but in fact...

Teratoscincus roborowskii

Teratoscincus roborowskii

Teratoscincus roborowskii,Chinese wonder gecko,Frog-eyed Gecko

Features:It was originally a subspecies of the Ili Sand Tiger, but was later separated

The foreign name of Turpan sand tiger is Chinese wonder gecko, and it has no subspecies.The feeding habits of Turpan sand tigers were studied using feces analysis. The results show that: from April to May, Turpan sand tigers feed on animal food, mainly small arthropods; from June to September, they...

Teratoscincus scincus

Teratoscincus scincus

Teratoscincus scincus,Common Wonder Gecko,Frog-eyed gecko, large (small) species of fine-scale frog eyes, Kashiwa sand tiger

Features:It is a typical nocturnal gecko.

Foreign name Common Wonder Gecko, no subspecies.The Ili Sand Tiger lives in the desert and desert steppe areas on the edge of the oasis. Ili sand tigers are typical nocturnal geckos. They usually do not come out to move during the day. They often hide in the burrows they dug in advance, which are ab...

Cobra

Cobra

Ophiophagus hannah,King Cobra

Features:The world's largest front-fanged venomous snake, one of the most dangerous snakes in the world, and the longest of all venomous snakes.

King cobra is different from real cobra. It is not a member of the genus Cobra, but belongs to the independent genus Cobra. Compared with other cobras, it is more ferocious, extremely quick to react, flexible in turning its head and neck, and has a large amount of venom. It is one of the most danger...

Chlamydosaurus kingii

Chlamydosaurus kingii

Frilled lizard, cloaked lizard, frilled lizard, Australian cloaked lizard, pleated lizard, wrinkled lizard

Features:When meeting an enemy, hold up an umbrella to intimidate them. If they fail to scare them, stand upright and run away.

伞蜥来自新几内亚南部和澳大利亚北部沿海地区,是一种知名度极高的中大型蜥蜴,在鬣蜥科属于第二大蜥蜴(最大的是斑帆蜥)。两种不同产地的伞蜥,体型颜色上会有明显区别,原产于澳洲的伞蜥体型更大,颜色偏棕红。而产于印尼的伞蜥体型稍小,颜色偏灰白。市面上常见的是来自印尼个体。大部分时间在树上,也会到地面上捕食。...

Varanus salvator

Varanus salvator

Water monitor, marsh monitor, five-clawed golden dragon, four-legged snake, round-nosed monitor

Features:The second largest lizard in the world.

Speaking of the nickname of the water monitor lizard, everyone is familiar with it, that is - the five-clawed golden dragon.Although the water monitor lizard looks unfriendly, it is actually very docile and very friendly to people. It is said to be a non-aggressive animal, and no cases of biting peo...

Chamaeleo calyptratus

Chamaeleo calyptratus

Veiled chameleon

Features:The easiest chameleon species to breed.

The veiled chameleon is native to Central Asia, such as Saudi Arabia and Yemen, so they have another name - Yemen chameleon. They are a relatively large chameleon and are also the most suitable chameleon for beginners to raise.When the mood is beautiful, the iridophore crystals are closely arranged,...

Morelia bredli

Morelia bredli

carpet python, felt python, central python

Features:The carpet python gets its name from its unique pattern that resembles a carpet.

All pythons are non-venomous, and carpet pythons are no exception.Carpet pythons strangle their prey by constricting their bodies. The species is usually active during the day and at night, with some subspecies being primarily nocturnal. Carpet pythons like to live in trees, although they usually ba...