From Wikipedia, the free encyclopedia

Temporal range:
Late Triassic–present [1]
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Superorder: Lepidosauria
Order: Squamata
Oppel, 1811
Subgroups [2]

Squamata ( /skwæˈmtə/, Latin squamatus, 'scaly, having scales') is the largest order of reptiles, comprising lizards, snakes, and amphisbaenians (worm lizards), which are collectively known as squamates or scaled reptiles. With over 10,900 species, [3] it is also the second-largest order of extant (living) vertebrates, after the perciform fish. Members of the order are distinguished by their skins, which bear horny scales or shields, and must periodically engage in molting. They also possess movable quadrate bones, making possible movement of the upper jaw relative to the neurocranium. This is particularly visible in snakes, which are able to open their mouths very wide to accommodate comparatively large prey. Squamata is the most variably sized order of reptiles, ranging from the 16 mm (0.63 in) dwarf gecko (Sphaerodactylus ariasae) to the 6.5 m (21 ft) Reticulated python (Malayopython reticulatus) and the now- extinct mosasaurs, which reached lengths over 14 m (46 ft).

Among other reptiles, squamates are most closely related to the tuatara, the last surviving member of the once diverse Rhynchocephalia, with both groups being placed in the clade Lepidosauria.


Slavoia darevskii, a fossil squamate

Squamates are a monophyletic sister group to the rhynchocephalians, members of the order Rhynchocephalia. The only surviving member of the Rhynchocephalia is the tuatara. Squamata and Rhynchocephalia form the subclass Lepidosauria, which is the sister group to the Archosauria, the clade that contains crocodiles and birds, and their extinct relatives. Fossils of rhynchocephalians first appear in the Early Triassic, meaning that the lineage leading to squamates must have also existed at the time. [4] [5] Scientists believe crown group squamates probably originated in the Early Jurassic based on the fossil record, [4] The first fossils of geckos, skinks, and snakes appear in the Middle Jurassic. [6] and their overall diversity was established during the mid-Jurassic, with further diversity expansions being mostly the result of added species. [7] Other groups like iguanians and varanoids appeared in the Cretaceous. Polyglyphanodontia, an extinct clade of lizards, and mosasaurs, a group of predatory marine lizards that grew to enormous sizes, also appeared in the Cretaceous. [8] Squamates suffered a mass extinction at the Cretaceous–Paleogene (K–PG) boundary, which wiped out polyglyphanodontians, mosasaurs, and many other distinct lineages. [9]

The relationships of squamates is debatable. Although many of the groups originally recognized on the basis of morphology are still accepted, understanding of their relationships to each other has changed radically as a result of studying their genomes. Iguanians were long thought to be the earliest crown group squamates based on morphological data, [8] but genetic data suggest that geckoes are the earliest crown group squamates. [10] Iguanians are now united with snakes and anguimorphs in a clade called Toxicofera. Genetic data also suggest that the various limbless groups - snakes, amphisbaenians, and dibamids - are unrelated, and instead arose independently from lizards.

A study in 2018 found that Megachirella, an extinct genus of lepidosaurs that lived about 240 million years ago during the Middle Triassic, was a stem-squamate, making it the oldest known squamate. The phylogenetic analysis was conducted by performing high-resolution microfocus X-ray computed tomography (micro-CT) scans on the fossil specimen of Megachirella to gather detailed data about its anatomy. These data were then compared with a phylogenetic dataset combining the morphological and molecular data of 129 extant and extinct reptilian taxa. The comparison revealed Megachirella had certain features that are unique to squamates. The study also found that geckos are the earliest crown group squamates, not iguanians. [11] [12]

In 2022, the extinct genus Cryptovaranoides was described from the Late Triassic of England. Cryptovaranoides appears to be a highly derived squamate belonging to the group Anguimorpha, which contains many extant lineages such as monitor lizards, beaded lizards and anguids. The presence of an essentially modern crown group squamate so far back in time indicates that the diversification of squamate lineages, which was previously thought to have occurred during the Jurassic and Cretaceous, occurred much earlier than previously theorized. The Triassic squamate diversification is thought to be linked to the Carnian Pluvial Episode, which was responsible for the diversification of many other groups of insects, plants, and vertebrates. [1]


Trachylepis maculilabris skinks mating

The male members of the group Squamata have hemipenes, which are usually held inverted within their bodies, and are everted for reproduction via erectile tissue like that in the mammalian penis. [13] Only one is used at a time, and some evidence indicates that males alternate use between copulations. The hemipenis has a variety of shapes, depending on the species. Often it bears spines or hooks, to anchor the male within the female. Some species even have forked hemipenes (each hemipenis has two tips). Due to being everted and inverted, hemipenes do not have a completely enclosed channel for the conduction of sperm, but rather a seminal groove that seals as the erectile tissue expands. This is also the only reptile group in which both viviparous and ovoviviparous species are found, as well as the usual oviparous reptiles. Some species, such as the Komodo dragon, can reproduce asexually through parthenogenesis. [14]

The Japanese striped snake has been studied in sexual selection.

Studies have been conducted on how sexual selection manifests itself in snakes and lizards. Snakes use a variety of tactics in acquiring mates. [15][ dubious ] Ritual combat between males for the females with which they want to mate includes topping, a behavior exhibited by most viperids, in which one male twists around the vertically elevated fore body of his opponent and forcing it downward. Neck biting commonly occurs while the snakes are entwined. [16]

Facultative parthenogenesis

The effects of central fusion and terminal fusion on heterozygosity

Parthenogenesis is a natural form of reproduction in which the growth and development of embryos occur without fertilization. Agkistrodon contortrix (copperhead snake) and Agkistrodon piscivorus (cottonmouth snake) can reproduce by facultative parthenogenesis; they are capable of switching from a sexual mode of reproduction to an asexual mode. [17] The type of parthenogenesis that likely occurs is automixis with terminal fusion (see figure), a process in which two terminal products from the same meiosis fuse to form a diploid zygote. This process leads to genome-wide homozygosity, expression of deleterious recessive alleles, and often to developmental abnormalities. Both captive-born and wild-born A. contortrix and A. piscivorus appear to be capable of this form of parthenogenesis. [17]

Reproduction in squamate reptiles is ordinarily sexual, with males having a ZZ pair of sex-determining chromosomes, and females a ZW pair. However, the Colombian rainbow boa, Epicrates maurus, can also reproduce by facultative parthenogenesis, resulting in production of WW female progeny. [18] The WW females are likely produced by terminal automixis.

Inbreeding avoidance

When female sand lizards mate with two or more males, sperm competition within the female's reproductive tract may occur. Active selection of sperm by females appears to occur in a manner that enhances female fitness. [19] On the basis of this selective process, the sperm of males that are more distantly related to the female are preferentially used for fertilization, rather than the sperm of close relatives. [19] This preference may enhance the fitness of progeny by reducing inbreeding depression.

Evolution of venom

Recent research suggests that the evolutionary origin of venom may exist deep in the squamate phylogeny, with 60% of squamates placed in this hypothetical group called Toxicofera. Venom has been known in the clades Caenophidia, Anguimorpha, and Iguania, and has been shown to have evolved a single time along these lineages before the three groups diverged, because all lineages share nine common toxins. [20] The fossil record shows the divergence between anguimorphs, iguanians, and advanced snakes dates back roughly 200 million years ago (Mya) to the Late Triassic/ Early Jurassic, [20] but the only good fossil evidence is from the Middle Jurassic. [21]

Snake venom has been shown to have evolved via a process by which a gene encoding for a normal body protein, typically one involved in key regulatory processes or bioactivity, is duplicated, and the copy is selectively expressed in the venom gland. [22] Previous literature hypothesized that venoms were modifications of salivary or pancreatic proteins, [23] but different toxins have been found to have been recruited from numerous different protein bodies and are as diverse as their functions. [24]

Natural selection has driven the origination and diversification of the toxins to counter the defenses of their prey. Once toxins have been recruited into the venom proteome, they form large, multigene families and evolve via the birth-and-death model of protein evolution, [25] which leads to a diversification of toxins that allows the ambush predators the ability to attack a wide range of prey. [26] The rapid evolution and diversification is thought to be the result of a predator–prey evolutionary arms race, where both are adapting to counter the other. [27]

Humans and squamates

Bites and fatalities

Map showing the global distribution of venomous snakebites

An estimated 125,000 people a year die from venomous snake bites. [28] In the US alone, more than 8,000 venomous snake bites are reported each year, but only one in 50 million people (five or six fatalities per year in the USA) will die from venomous snake bites. [29] [30]

Lizard bites, unlike venomous snake bites, are usually not fatal. The Komodo dragon has been known to kill people due to its size, and recent studies show it may have a passive envenomation system. Recent studies also show that the close relatives of the Komodo, the monitor lizards, all have a similar envenomation system, but the toxicity of the bites is relatively low to humans. [31] The Gila monster and beaded lizards of North and Central America are venomous, but not deadly to humans.


Though they survived the Cretaceous–Paleogene extinction event, many squamate species are now endangered due to habitat loss, hunting and poaching, illegal wildlife trading, alien species being introduced to their habitats (which puts native creatures at risk through competition, disease, and predation), and other anthropogenic causes. Because of this, some squamate species have recently become extinct, with Africa having the most extinct species. Breeding programs and wildlife parks, though, are trying to save many endangered reptiles from extinction. Zoos, private hobbyists, and breeders help educate people about the importance of snakes and lizards.

Classification and phylogeny

Desert iguana from Amboy Crater, Mojave Desert, California

Historically, the order Squamata has been divided into three suborders:

Of these, the lizards form a paraphyletic group, [32] since "lizards" excludes the subclades of snakes and amphisbaenians. Studies of squamate relationships using molecular biology have found several distinct lineages, though the specific details of their interrelationships vary from one study to the next. One example of a modern classification of the squamates is [2] [33]




Diplodactylidae Underwood 1954 Hoplodactylus pomarii white background.jpg

Pygopodidae Boulenger 1884 The zoology of the voyage of the H.M.S. Erebus and Terror (Lialis burtonis).jpg





Sphaerodactylidae Underwood 1954

Phyllodactylidae Phyllodactylus gerrhopygus 1847 - white background.jpg



Scincidae Natural history of Victoria (Egernia cunninghami).jpg



Gerrhosauridae Gerrhosaurus ocellatus flipped.jpg

Cordylidae Illustrations of the zoology of South Africa (Smaug giganteus).jpg


Gymnophthalmidae Merrem 1820 PZSL1851PlateReptilia06 Cercosaura ocellata.png

Teiidae Gray 1827 Bilder-Atlas zur wissenschaftlich-populären Naturgeschichte der Wirbelthiere (Tupinambis teguixin).jpg


Lacertidae Brockhaus' Konversations-Lexikon (1892) (Lacerta agilis).jpg


Rhineuridae Vanzolini 1951

Bipedidae Taylor 1951 Bilder-Atlas zur wissenschaftlich-populären Naturgeschichte der Wirbelthiere (Bipes canaliculatus).jpg

Blanidae Kearney & Stuart 2004 Blanus cinereus flipped.jpg

Cadeidae Vidal & Hedges 2008

Trogonophidae Gray 1865

Amphisbaenidae Gray 1865 Amphisbaena microcephalum 1847 - white background.jpg


Shinisauridae Ahl 1930 sensu Conrad 2006



Varanidae Zoology of Egypt (1898) (Varanus exanthematicus).png


Helodermatidae Gray 1837 Gila monster ncd 2012 white background.jpg






Anguidae Gray 1825


Chamaeleonidae Zoology of Egypt (1898) (Chamaeleo calyptratus).jpg

Agamidae Gray 1827 Haeckel Lacertilia (Chlamydosaurus kingii).jpg



Iguanidae Stamps of Germany (Berlin) 1977, Cyclura cornuta.jpg

Hoplocercidae Frost & Etheridge 1989











Leptotyphlopidae Stejneger 1892 Epictia tenella 1847 -white background.jpg

Gerrhopilidae Vidal et al. 2010

Xenotyphlopidae Vidal et al. 2010

Typhlopidae Merrem 1820 Typhlops vermicularis3 white background.jpg




Tropidophiidae Brongersma 1951


Uropeltidae Uropeltis ceylanica (2) flipped.jpg


Cylindrophiidae Cylind resplendens Wagler white background.JPG

Xenopeltidae Bonaparte 1845


Pythonidae Fitzinger 1826 Python natalensis Smith 1840 white background.jpg

Boidae Boa constrictor - 1800-1839 - Print - Iconographia Zoologica - (white background).jpg


Bolyeriidae Hoffstetter 1946


Acrochordidae Bonaparte 1831




Viperidae Illustrations of the zoology of South Africa (Bitis caudalis).jpg



Colubridae Xenochrophis piscator 1 Hardwicke white background.jpg


Elapidae Bilder-Atlas zur wissenschaftlich-populären Naturgeschichte der Wirbelthiere (Naja naja).jpg

All recent molecular studies [20] suggest that several groups form a venom clade, which encompasses a majority (nearly 60%) of squamate species. Named Toxicofera, it combines the groups Serpentes (snakes), Iguania (agamids, chameleons, iguanids, etc.), and Anguimorpha (monitor lizards, Gila monster, glass lizards, etc.). [20]

List of extant families

The over 10,900 extant squamates are divided into 60 families.

Family Common names Example species Example photo
Gray, 1865
Tropical worm lizards Darwin's worm lizard ( Amphisbaena darwinii) Amphisbaenidae - Amphisbaena darwinii.JPG
Taylor, 1951
Bipes worm lizards Mexican mole lizard (Bipes biporus) Bipes biporus.jpg
Kearney, 2003
Mediterranean worm lizards Mediterranean worm lizard ( Blanus cinereus) Culebra Ciega - panoramio.jpg
Vidal & Hedges, 2007 [34]
Cuban worm lizards Cadea blanoides Cadea palirostrata Dickerson 1916.jpg
Vanzolini, 1951
North American worm lizards North American worm lizard (Rhineura floridana) Amphisbaenia 1.jpg
Gray, 1865
Palearctic worm lizards Checkerboard worm lizard (Trogonophis wiegmanni) Trogonophis wiegmanni imported from iNaturalist photo 24355639 on 14 January 2020.jpg
Gekkota (geckos, incl. Dibamia)
Family Common names Example species Example photo
Kluge, 1967
Southern padless geckos Thick-tailed gecko (Underwoodisaurus milii) Thick-tailed Gecko (Underwoodisaurus milii) (8636512143).jpg
Boulenger, 1884
Blind lizards Dibamus nicobaricum Anelytropsis.jpg
Underwood, 1954
Australasian geckos Golden-tailed gecko (Strophurus taenicauda) Golden Tailed Gecko.jpg
Boulenger, 1883
Eyelid geckos Common leopard gecko (Eublepharis macularius) Eublepharis macularius1.jpg
Gray, 1825
Geckos Madagascar giant day gecko (Phelsuma grandis) Madagascar giant day gecko (Phelsuma grandis) Nosy Komba.jpg
Gamble et al., 2008
Geckos Moorish gecko (Tarentola mauritanica) Konstantinos Kalaentzis Tarentola mauritanica (A1).jpg
Boulenger, 1884
Flap-footed lizards Burton's snake lizard (Lialis burtonis) Lialis burtonis.jpg
Underwood, 1954
Geckos Fantastic least gecko (Sphaerodactylus fantasticus) Sphaerodactylus fantasticus fantasticus (51113243252).jpg
Family Common names Example species Example photo
Gray, 1827
Agamas Eastern bearded dragon (Pogona barbata) Bearded dragon04.jpg
Rafinesque, 1815
Chameleons Veiled chameleon (Chamaeleo calyptratus) Chamaelio calyptratus.jpg
Fitzinger, 1843
Casquehead lizards Plumed basilisk (Basiliscus plumifrons) Plumedbasiliskcele4 edit.jpg
H.M. Smith & Brodie, 1982
Collared and leopard lizards Common collared lizard (Crotaphytus collaris) Collared lizard in Zion National Park.jpg
Fitzinger, 1843
Anoles Carolina anole (Anolis carolinensis) Anolis carolinensis.jpg
Frost & Etheridge, 1989
Wood lizards or clubtails Enyalioides binzayedi Holotype of Enyalioides binzayedi - ZooKeys-277-069-g007-top.jpg
Oppel, 1811
Iguanas Marine iguana (Amblyrhynchus cristatus) Marineiguana03.jpg
Frost & Etheridge, 1989
Curly-tailed lizards Hispaniolan masked curly-tailed lizard (Leiocephalus personatus) Leiocephalus-personatus-maskenleguan.jpg
Frost et al., 2001
Leiosaurid lizards Enyalius bilineatus Enyalius bilineatus no Parque Estadual de Caparao por Lucas Rosado (08).jpg
Frost & Etheridge, 1989
Tree iguanas, snow swifts Shining tree iguana (Liolaemus nitidus) Atacama lizard1.jpg
Titus & Frost, 1996
Malagasy iguanas Chalarodon madagascariensis Chalarodon madagascariensis male.jpg
Fitzinger, 1843
Earless, spiny, tree, side-blotched and horned lizards Greater earless lizard (Cophosaurus texanus) Reptile tx usa.jpg
Frost & Etheridge, 1989
Bush anoles Brazilian bush anole (Polychrus acutirostris) Polychrus acutirostris.JPG
Bell, 1843
Neotropical ground lizards Microlophus peruvianus Mperuvianus.jpg
Lacertoidea (excl. Amphisbaenia)
Family Common Names Example Species Example Photo
Goicoechea, Frost, De la Riva, Pellegrino, Sites Jr., Rodrigues, & Padial, 2016
Alopoglossid lizards Alopoglossus vallensis Ptychoglossus vallensis.jpg
Fitzinger, 1826
Spectacled lizards Bachia bicolor Bachia bicolor.jpg
Oppel, 1811
Wall lizards Ocellated lizard (Lacerta lepida) Perleidechse-20.jpg
Gray, 1827
Tegus and whiptails Gold tegu (Tupinambis teguixin) Goldteju Tupinambis teguixin.jpg
Family Common names Example species Example photo
Gray, 1825
Glass lizards, alligator lizards and slowworms Slowworm ( Anguis fragilis) Anguidae.jpg
Boulenger, 1885
American legless lizards California legless lizard (Anniella pulchra) Anniella pulchra.jpg
Bocourt, 1873
galliwasps, legless lizards Jamaican giant galliwasp (Celestus occiduus) Celestus occiduus museum specimen.jpeg-
Gray, 1837
Beaded lizards Gila monster (Heloderma suspectum)
Steindachner, 1877
Earless monitor Earless monitor (Lanthanotus borneensis) Real Lanthanotus borneensis.jpg
Ahl, 1930
Chinese crocodile lizard Chinese crocodile lizard (Shinisaurus crocodilurus) Chin-krokodilschwanzechse-01.jpg
Merrem, 1820
Monitor lizards Perentie (Varanus giganteus) Perentie Lizard Perth Zoo SMC Spet 2005.jpg
Cope, 1866
Knob-scaled lizards Mexican knob-scaled lizard (Xenosaurus grandis) Xenosaurus grandis.jpg
Family Common Names Example Species Example Photo
Fitzinger, 1826
Girdled lizards Girdle-tailed lizard (Cordylus warreni) Cordylus breyeri1.jpg
Fitzinger, 1843
Plated lizards Sudan plated lizard (Gerrhosaurus major) Gerrhosaurus major.jpg
Oppel, 1811
Skinks Western blue-tongued skink (Tiliqua occipitalis) Tiliqua occipitalis.jpg
Baird, 1858
Night lizards Granite night lizard (Xantusia henshawi) Xantusia henshawi.jpg
Family Common names Example species Example photo
Bonaparte, 1831 [35]
File snakes Marine file snake (Acrochordus granulatus) Wart snake 1.jpg
Stejneger, 1907 [36]
Coral pipe snakes Burrowing false coral (Anilius scytale) False Coral Snake (Anilius scytale) close-up (13929278050).jpg
Cundall, Wallach and Rossman, 1993. [37]
Dwarf pipe snakes Leonard's pipe snake, (Anomochilus leonardi) Anomochilus weberi.jpg
Gray, 1825 [35] (incl. Calabariidae)
Boas Amazon tree boa (Corallus hortulanus) Corallushortulanus.png
Hoffstetter, 1946
Round Island boas Round Island burrowing boa (Bolyeria multocarinata) Round Island Boa.jpeg
Oppel, 1811 [35] sensu lato (incl. Dipsadidae, Natricidae, Pseudoxenodontidae)
Colubrids Grass snake (Natrix natrix) Natrix natrix (Marek Szczepanek).jpg
Fitzinger, 1843
Asian pipe snakes Red-tailed pipe snake (Cylindrophis ruffus) Cylindrophis rufus.jpg
Boie, 1827 [35]
Cobras, coral snakes, mambas, kraits, sea snakes, sea kraits, Australian elapids King cobra (Ophiophagus hannah) Ophiophagus hannah2.jpg
Bonaparte, 1845
Indo-Australian water snakes, mudsnakes, bockadams New Guinea bockadam (Cerberus rynchops) HerpetonTentaculatumFord.jpg
Fitzinger, 1843 [38]
Lamprophiid snakes Bibron's burrowing asp (Atractaspis bibroni) Lamprophis fuliginosus02.jpg
Cope, 1861
Mexican burrowing snakes Mexican burrowing snake (Loxocemus bicolor) Loxocemus bicolor.jpg
Romer, 1956
Pareid snakes Perrotet's mountain snake (Xylophis perroteti) Xylophis sp. Munnar.jpg
Fitzinger, 1826
Pythons Ball python (Python regius) Ball python lucy.JPG
Brongersma, 1951
Dwarf boas Northern eyelash boa (Trachyboa boulengeri) Cuban Giant Trope (Tropidophis melanurus) (8577519420).jpg
Müller, 1832
Shield-tailed snakes, short-tailed snakes Cuvier's shieldtail (Uropeltis ceylanica) Silybura shortii.jpg
Oppel, 1811 [35]
Vipers, pitvipers, rattlesnakes European asp (Vipera aspis) Vipera aspis aspis, Lorraine, France.jpg
Fitzinger, 1826
Odd-scaled snakes and relatives Khase earth snake (Stoliczkia khasiensis) Achalinus formosanus formosanus full body shot.jpg
Gray, 1849
Sunbeam snakes Sunbeam snake (Xenopeltis unicolor) XenopeltisUnicolorRooij.jpg
Scolecophidia (incl. Anomalepidae)
Family Common names Example species Example photo
Taylor, 1939 [35]
Dawn blind snakes Dawn blind snake (Liotyphlops beui) Liotyphlops beui.jpg
Vidal et al., 2010 [34]
Indo-Malayan blindsnakes Andaman worm snake (Gerrhopilus andamanensis)
Stejneger, 1892 [35]
Slender blind snakes Texas blind snake (Leptotyphlops dulcis) Leptotyphlops dulcis.jpg
Merrem, 1820 [39]
Blind snakes European blind snake (Typhlops vermicularis) Typhlops vermicularis.jpg
Vidal et al., 2010 [34]
Malagasy blind snakes Xenotyphlops grandidieri


  1. ^ a b Whiteside, David I.; Chambi-Trowell, Sofía A. V.; Benton, Michael J. (2 December 2022). "A Triassic crown squamate". Science Advances. 8 (48): eabq8274. doi: 10.1126/sciadv.abq8274. ISSN  2375-2548. PMID  36459546. S2CID  254180027.
  2. ^ a b Wiens, J. J.; Hutter, C. R.; Mulcahy, D. G.; Noonan, B. P.; Townsend, T. M.; Sites, J. W.; Reeder, T. W. (2012). "Resolving the phylogeny of lizards and snakes (Squamata) with extensive sampling of genes and species". Biology Letters. 8 (6): 1043–1046. doi: 10.1098/rsbl.2012.0703. PMC  3497141. PMID  22993238. {{ cite journal}}: Check |author1-link= value ( help); Check |author3-link= value ( help); Check |author4-link= value ( help)
  3. ^ "Species Numbers (as of May 2021)". Retrieved 28 July 2021.{{ cite web}}: CS1 maint: url-status ( link)
  4. ^ a b Jones, Marc E.; Anderson, Cajsa Lipsa; Hipsley, Christy A.; Müller, Johannes; Evans, Susan E.; Schoch, Rainer R. (25 September 2013). "Integration of molecules and new fossils supports a Triassic origin for Lepidosauria (lizards, snakes, and tuatara)". BMC Evolutionary Biology. 13: 208. doi: 10.1186/1471-2148-13-208. PMC  4016551. PMID  24063680.
  5. ^ Bolet, Arnau; Stubbs, Thomas L.; Herrera-Flores, Jorge A.; Benton, Michael J. (2022). "The Jurassic rise of squamates as supported by lepidosaur disparity and evolutionary rates". eLife. 11. doi: 10.7554/eLife.66511. PMC  9064307. PMID  35502582.
  6. ^ Caldwell, M. W.; Nydam, R. L.; Palci, A.; Apesteguía, S. N. [in Spanish] (27 January 2015). "The oldest known snakes from the Middle Jurassic-Lower Cretaceous provide insights on snake evolution". Nature Communications. 6: 5996. Bibcode: 2015NatCo...6.5996C. doi: 10.1038/ncomms6996. ISSN  2041-1723. PMID  25625704. {{ cite journal}}: Check |author1-link= value ( help); Check |author2-link= value ( help)
  7. ^ Bolet, Arnau; Stubbs, Thomas L.; Herrera-Flores, Jorge A.; Benton, Michael J. (2022). "The Jurassic rise of squamates as supported by lepidosaur disparity and evolutionary rates". eLife. 11 (10): 532–534. doi: 10.7554/eLife.66511. PMC  9064307. PMID  3550582.
  8. ^ a b Gauthier, Jacques; Kearney, Maureen; Maisano, Jessica Anderson; Rieppel, Olivier; Behlke, Adam D. B. (April 2012). "Assembling the squamate tree of life: perspectives from the phenotype and the fossil record". Bulletin of the Peabody Museum of Natural History. 53: 3–308. doi: 10.3374/014.053.0101. S2CID  86355757.
  9. ^ Longrich, Nicholas R.; Bhullar, Bhart-Anjan S.; Gauthier, Jacques (10 December 2012). "Mass extinction of lizards and snakes at the Cretaceous-Paleogene boundary". Proceedings of the National Academy of Sciences. 109 (52): 21396–21401. Bibcode: 2012PNAS..10921396L. doi: 10.1073/pnas.1211526110. PMC  3535637. PMID  23236177. {{ cite journal}}: Check |author1-link= value ( help)
  10. ^ Pyron, R. Alexander; Burbrink, Frank T.; Wiens, John J. (29 April 2013). "A phylogeny and revised classification of Squamata, including 4161 species of lizards and snakes". BMC Evolutionary Biology. 13: 93. doi: 10.1186/1471-2148-13-93. PMC  3682911. PMID  23627680. {{ cite journal}}: Check |author1-link= value ( help); Check |author2-link= value ( help); Check |author3-link= value ( help)
  11. ^ Simōes, Tiago R.; Caldwell, Michael W.; Talanda, Mateusz; Bernardi, Massimo; Palci, Alessandro; Vernygora, Oksana; Bernardini, Federico; Mancini, Lucia; Nydam, Randall L. (30 May 2018). "The origin of squamates revealed by a Middle Triassic lizard from the Italian Alps". Nature. 557 (7707): 706–709. Bibcode: 2018Natur.557..706S. doi: 10.1038/s41586-018-0093-3. PMID  29849156. S2CID  44108416. {{ cite journal}}: Check |author2-link= value ( help); Check |author9-link= value ( help)
  12. ^ Weisberger, Mindy (30 May 2018). "This 240-Million-Year-Old Reptile Is the 'Mother of All Lizards'". Live Science. Purch Group. Retrieved 2 June 2018.
  13. ^ "Iguana Anatomy".
  14. ^ Morales, Alex (20 December 2006). "Komodo Dragons, World's Largest Lizards, Have Virgin Births". Bloomberg Television. Retrieved 28 March 2008.
  15. ^ Shine, Richard; Langkilde, Tracy; Mason, Robert T (2004). "Courtship tactics in garter snakes: How do a male's morphology and behaviour influence his mating success?". Animal Behaviour. 67 (3): 477–83. doi: 10.1016/j.anbehav.2003.05.007. S2CID  4830666.
  16. ^ Blouin-Demers, Gabriel; Gibbs, H. Lisle; Weatherhead, Patrick J. (2005). "Genetic evidence for sexual selection in black ratsnakes, Elaphe obsoleta". Animal Behaviour. 69 (1): 225–34. doi: 10.1016/j.anbehav.2004.03.012. S2CID  3907523.
  17. ^ a b Booth W, Smith CF, Eskridge PH, Hoss SK, Mendelson JR, Schuett GW (2012). "Facultative parthenogenesis discovered in wild vertebrates". Biology Letters. 8 (6): 983–5. doi: 10.1098/rsbl.2012.0666. PMC  3497136. PMID  22977071.
  18. ^ Booth W, Million L, Reynolds RG, Burghardt GM, Vargo EL, Schal C, Tzika AC, Schuett GW (2011). "Consecutive virgin births in the new world boid snake, the Colombian rainbow Boa, Epicrates maurus". Journal of Heredity. 102 (6): 759–63. doi: 10.1093/jhered/esr080. PMID  21868391.
  19. ^ a b Olsson M, Shine R, Madsen T, Gullberg A, Tegelström H (1997). "Sperm choice by females". Trends in Ecology & Evolution. 12 (11): 445–6. doi: 10.1016/s0169-5347(97)85751-5. PMID  21238151.
  20. ^ a b c d Fry, Brian G.; Vidal, Nicolas; Norman, Janette A.; Vonk, Freek J.; Scheib, Holger; Ramjan, S.F. Ryan; et al. (February 2006). "Early evolution of the venom system in lizards and snakes". Nature. 439 (7076): 584–588. Bibcode: 2006Natur.439..584F. doi: 10.1038/nature04328. PMID  16292255. S2CID  4386245.
  21. ^ Hutchinson, M. N.; Skinner, A.; Lee, M. S. Y. (2012). "Tikiguania and the antiquity of squamate reptiles (lizards and snakes)". Biology Letters. 8 (4): 665–669. doi: 10.1098/rsbl.2011.1216. PMC  3391445. PMID  22279152.
  22. ^ Fry, B. G.; Vidal, N.; Kochva, E.; Renjifo, C. (2009). "Evolution and diversification of the toxicofera reptile venom system". Journal of Proteomics. 72 (2): 127–136. doi: 10.1016/j.jprot.2009.01.009. PMID  19457354.
  23. ^ Kochva, E (1987). "The origin of snakes and evolution of the venom apparatus". Toxicon. 25 (1): 65–106. doi: 10.1016/0041-0101(87)90150-4. PMID  3564066.
  24. ^ Fry, B. G. (2005). "From genome to "Venome": Molecular origin and evolution of the snake venom proteome inferred from phylogenetic analysis of toxin sequences and related body proteins". Genome Research. 15 (3): 403–420. doi: 10.1101/gr.3228405. PMC  551567. PMID  15741511.
  25. ^ Fry, B. G.; Scheib, H.; Young, B.; McNaughtan, J.; Ramjan, S. F. R.; Vidal, N. (2008). "Evolution of an arsenal". Molecular & Cellular Proteomics. 7 (2): 215–246. doi: 10.1074/mcp.m700094-mcp200. PMID  17855442.
  26. ^ Calvete, J. J.; Sanz, L.; Angulo, Y.; Lomonte, B.; Gutierrez, J. M. (2009). "Venoms, venomics, antivenomics". FEBS Letters. 583 (11): 1736–1743. doi: 10.1016/j.febslet.2009.03.029. PMID  19303875. S2CID  904161.
  27. ^ Barlow, A.; Pook, C. E.; Harrison, R. A.; Wuster, W. (2009). "Coevolution of diet and prey-specific venom activity supports the role of selection in snake venom evolution". Proceedings of the Royal Society B: Biological Sciences. 276 (1666): 2443–2449. doi: 10.1098/rspb.2009.0048. PMC  2690460. PMID  19364745.
  28. ^ "Snake-bites: appraisal of the global situation" (PDF). World Health Organization. Retrieved 30 December 2007.
  29. ^ "Venomous Snake FAQs". University of Florida. Retrieved 17 September 2019.
  30. ^ "First Aid Snake Bites". University of Maryland Medical Center. Retrieved 30 December 2007.
  31. ^ "Komodo dragon kills boy, 8, in Indonesia". NBC News. Retrieved 30 December 2007.
  32. ^ Reeder, Tod W.; Townsend, Ted M.; Mulcahy, Daniel G.; Noonan, Brice P.; Wood, Perry L.; Sites, Jack W.; Wiens, John J. (2015). "Integrated Analyses Resolve Conflicts over Squamate Reptile Phylogeny and Reveal Unexpected Placements for Fossil Taxa". PLOS One. 10 (3): e0118199. Bibcode: 2015PLoSO..1018199R. doi: 10.1371/journal.pone.0118199. PMC  4372529. PMID  25803280. {{ cite journal}}: Check |author3-link= value ( help); Check |author4-link= value ( help); Check |author7-link= value ( help)
  33. ^ Zheng, Yuchi; Wiens, John J. (2016). "Combining phylogenomic and supermatrix approaches, and a time-calibrated phylogeny for squamate reptiles (lizards and snakes) based on 52 genes and 4162 species". Molecular Phylogenetics and Evolution. 94 (Part B): 537–547. doi: 10.1016/j.ympev.2015.10.009. PMID  26475614. {{ cite journal}}: Check |author2-link= value ( help)
  34. ^ a b c S. Blair Hedges. "Families described". Hedges Lab | Evolutionary Biology.
  35. ^ a b c d e f g Cogger(1991), p.23
  36. ^ "Aniliidae". Integrated Taxonomic Information System. Retrieved 12 December 2007.
  37. ^ "Anomochilidae". Integrated Taxonomic Information System. Retrieved 13 December 2007.
  38. ^ "Atractaspididae". Integrated Taxonomic Information System. Retrieved 13 December 2007.
  39. ^ "Typhlopidae". Integrated Taxonomic Information System. Retrieved 13 December 2007.

Further reading

External links