Lizard

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For other uses, see Lizard (disambiguation).
Lizards
Fossil range: Early JurassicHolocene, 199–0 Ma
Possible Late Triassic record
Central bearded dragon, Pogona vitticeps
Central bearded dragon, Pogona vitticeps
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Superclass: Tetrapoda
Class: Reptilia
Order: Squamata
Suborder: Lacertilia*
Günther, 1867
Included groups
Anguimorpha
Gekkota
Iguania
Lacertoidea
Scincomorpha
Excluded groups
Serpentes
Synonyms

Sauria Macartney, 1802

Lizards are a widespread group of squamate reptiles, with over 6,000 species,[1] ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic as it excludes the snakes which are also squamates.

Biology

Morphology

Lizards typically have four legs feet and external ears, though some are legless, while snakes lack both of these characteristics. Lizards and snakes share a movable quadrate bone, distinguishing them from the sphenodonts, which have more primitive and solid diapsid skulls.

Lizards form about 60% of all the species of extant non-avian reptiles.

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 to nearly 3 m (9.8 ft) in the case of the largest living varanid lizard, the Komodo dragon. Some extinct varanids reached great size: The giant monitor Megalania is estimated to have reached up to 7 m (23 ft) long; while the extinct aquatic mosasaurs reached 17 m (56 ft).

Signalling

A Green Anole (Anolis carolinensis) signalling with its extended dewlap
Further information: Signalling theory

Vision, including color vision, is particularly well developed in most lizards. Most lizards communicate using body language, using specific postures, gestures, and movements to define territory, resolve disputes, and entice mates. Some species of lizards also use pheromones or bright colors, such as the iridescent patches on the belly of Sceloporus. These colors are highly visible to predators, so are often hidden on the underside or between scales and only revealed when necessary. The particular innovation in this respect is the dewlap, a brightly colored patch of skin on the throat, usually hidden between scales. When a display is needed, a lizard can erect the hyoid bone of its throat, resulting in a large vertical flap of brightly colored skin beneath the head which can be then used for communication. Anoles are particularly famous for this display, with each species having specific colors, including patterns only visible under ultraviolet (UV) light, as many lizards can see UV light.[2]

Shedding and regenerating tails

Lizard tail autotomy

Lizard tails are often a different and dramatically more vivid color than the rest of the body so as to encourage potential predators to strike for the tail first. Many lizards, including geckos and skinks, are capable of shedding part of their tails through a process called autotomy. This is an example of the pars pro toto principle, sacrificing "a part for the whole", and is employed by lizards to allow them to escape from predators. The detached tail writhes and wiggles, creating a deceptive sense of continued struggle, distracting the predator's attention from the fleeing prey animal. The lizard partially regenerates its tail over a period of weeks. A 2014 research identified 326 genes involved in the regeneration of lizard tails.[3] The new section contains cartilage rather than bone, and the skin may be discolored compared to the rest of the body.

Reproduction

Most lizards are oviparous (egg laying), though in some species the eggs are retained until the live young emerge (ovoviviparity). Parthenogenesis (reproduction from unfertilised eggs) occurs in at least 50 species and may be much more widespread in the group.[4][5]

Sexual selection in lizards shows evidence of female mate choice, favouring males display fitness indicators, such as fewer ectoparasites.[6]

Evolution

Fossil history

The earliest known fossil remains of a lizard belong to the iguanian species Tikiguania estesi, found in the Tiki Formation of India, which dates to the Carnian stage of the Triassic period, about 220 million years ago.[7] However, doubt has been raised over the age of Tikiguania because it is almost indistinguishable from modern agamid lizards. The Tikiguania remains may instead be late Tertiary or Quaternary in age, having been washed into much older Triassic sediments.[8] Lizards are most closely related to the Rhynchocephalia, which appeared in the Late Triassic, so the earliest lizards probably appeared at that time.[8] Mitochondrial phylogenetics suggest that the first lizards evolved in the late Permian. It had been thought on the basis of morphological data that iguanid lizards diverged from other squamates very early on, but molecular evidence contradicts this.[9]

Phylogeny

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.[10] The cladogram is based on genomic analysis by Wiens and colleagues in 2012 and 2016.[11][12]


Squamata
Dibamia

Dibamidae


Bifurcata
Gekkota
Pygopodomorpha

Diplodactylidae Hoplodactylus pomarii white background.jpg




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



Carphodactylidae




Gekkomorpha

Eublepharidae


Gekkonoidea

Sphaerodactylidae




Phyllodactylidae Phyllodactylus gerrhopygus 1847 - white background.jpg



Gekkonidae






Unidentata
Scinciformata
Scincomorpha

ScincidaeBilder-Atlas zur wissenschaftlich-populären Naturgeschichte der Wirbelthiere (Plate (24)) Tribolonotus novaeguineae.jpg


Cordylomorpha

Xantusiidae




GerrhosauridaeGerrhosaurus ocellatus flipped.jpg



CordylidaeIllustrations of the zoology of South Africa (Smaug giganteus).jpg





Episquamata
Laterata
Teiformata

Gymnophthalmidae PZSL1851PlateReptilia06 Cercosaura ocellata.png



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



Lacertibaenia
Lacertiformata

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



AMPHISBAENIA (worm lizards, not usually considered "true lizards") Amphisbaena microcephalum 1847 - white background.jpg




Toxicofera

Anguimorpha
Palaeoanguimorpha
Shinisauria

Shinisauridae


Varanoidea

Lanthanotidae



VaranidaeZoology of Egypt (1898) (Varanus griseus).png




Neoanguimorpha
Helodermatoidea

Helodermatidae Gila monster ncd 2012 white background.jpg



Xenosauroidea

Xenosauridae


Anguioidea

Diploglossidae




Anniellidae



Anguidae







Iguania
Acrodonta

ChamaeleonidaeZoology of Egypt (1898) (Chamaeleo calyptratus).jpg



Agamidae Haeckel Lacertilia (Chlamydosaurus kingii).jpg



Pleurodonta

Leiocephalidae




IguanidaeStamps of Germany (Berlin) 1977, Cyclura cornuta.jpg





Hoplocercidae




Crotaphytidae



Corytophanidae






Tropiduridae





Phrynosomatidae




Dactyloidae



Polychrotidae






Liolaemidae




Leiosauridae



Opluridae












SERPENTES (snakes, not considered to be lizards) Python natalensis Smith 1840 white background.jpg








Taxonomy

The name Sauria was coined by James Macartney (1802);[13] 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,[14] 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.[15] 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.[16] However, neither of these uses have gained wide acceptance among researchers specializing in lizards.

Suborder Lacertilia (Sauria) – (lizards)

Relationship with humans

Green iguanas (Iguana iguana), are popular pets.

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 (365 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.[17]

Numerous species of lizard are kept as pets, including bearded dragons, iguanas, anoles, and geckos (such as the popular leopard gecko).[citation needed]

Lizard symbolism plays a role in some cultures (e.g., Tarrotarro in Australian Aboriginal mythology). The Moche people of ancient Peru worshipped animals and often depicted lizards in their art.[18] According to a popular legend in Maharashtra, a common Indian monitor, with ropes attached, was used to scale the walls of the Sinhagad fort in the Battle of Sinhagad.[19]

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,[20] and 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.[21]

References

  1. ^ Reptile Database. Retrieved on 2012-04-22
  2. ^ "Reptile Lighting Information". reptilesmagazine. Retrieved 31 August 2015. 
  3. ^ Scientists discover how lizards regrow tails, The Independent, August 20, 2014
  4. ^ Macculloch, Ross; Robert Murphy; Larissa Kupriyanova; Ilya Darevsky (January 1997). "The Caucasian rock lizard Lacerta rostombekovi: a monoclonal parthenogenetic vertebrate". Biochemical Systematics and Ecology. 25 (1): 33–37. doi:10.1016/S0305-1978(96)00085-3. Retrieved 19 April 2014. 
  5. ^ Vitt, Laurie J., and Janalee P. Caldwell. Herpetology: an introductory biology of amphibians and reptiles. Academic Press, 2013.
  6. ^ Charles, G.; Ord, T. (2012). "Factors Leading to the Evolution Maintenance of a Male Ornament in Territorial Species". Behavioral Ecology and Sociobiology. 11: 127–31. 
  7. ^ Datta, P.M. & Ray, S. (2006). "Earliest lizards from the Late Triassic (Carnian) of India". Journal of Vertebrate Paleontology. 26 (4): 95–800. doi:10.1671/0272-4634(2006)26[795:ELFTLT]2.0.CO;2. 
  8. ^ a b Hutchinson, M.N.; Skinner, A.; Lee, M.S.Y. (2012). "Tikiguania and the antiquity of squamate reptiles (lizards and snakes)". Biology Letters. 8 (4): 665–9. doi:10.1098/rsbl.2011.1216. PMC 3391445Freely accessible. PMID 22279152. 
  9. ^ Kumazawa, Yoshinori (2007). "Mitochondrial genomes from major lizard families suggest their phylogenetic relationships and ancient radiations". Gene. 388 (1–2): 19–26. doi:10.1016/j.gene.2006.09.026. PMID 17118581. 
  10. ^ 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. doi:10.1371/journal.pone.0118199. PMC 4372529Freely accessible. PMID 25803280. 
  11. ^ 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 3497141Freely accessible. PMID 22993238. 
  12. ^ 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: 537–547. doi:10.1016/j.ympev.2015.10.009. 
  13. ^ James Macartney: Table III in: George Cuvier (1802) "Lectures on Comparative Anatomy" (translated by William Ross under the inspection of James Macartney). Vol I. London, Oriental Press, Wilson and Co.
  14. ^ Alexandre Brongniart (1800) "Essai d’une classification naturelle des reptiles. 1ère partie: Etablissement des ordres." Bulletin de la Science. Société Philomathique de Paris 2 (35): 81-82
  15. ^ Gauthier, J. A.; Kluge, A. G.; Rowe, T. (June 1988). "Amniote phylogeny and the importance of fossils". Cladistics. John Wiley & Sons. 4 (2): 105–209. doi:10.1111/j.1096-0031.1988.tb00514.x. 
  16. ^ Debraga, M. & Rieppel, O. (1997). "Reptile phylogeny and the interrelationships of turtles". Zoological Journal of the Linnean Society. 120 (3): 281–354. doi:10.1111/j.1096-3642.1997.tb01280.x. 
  17. ^ Komodo dragon kills boy in Indonesia – World news – Asia-Pacific – msnbc.com. MSNBC. Retrieved on 2011-11-07.
  18. ^ Berrin, Katherine & Larco Museum. The Spirit of Ancient Peru:Treasures from the Museo Arqueológico Rafael Larco Herrera. New York: Thames and Hudson, 1997.
  19. ^ Auffenberg, Walter (1994). The Bengal Monitor. University Press of Florida. p. 494. ISBN 0-8130-1295-3. 
  20. ^ Referencias culturales - todo iguanas verdes
  21. ^ Grzimek, Bernhard. Grzimek’s Animal Life Encyclopedia (Second Edition) Vol 7 – Reptiles. (2003) Thomson – Gale. Farmington Hills, Minnesota. Vol Editor – Neil Schlager. ISBN 0-7876-5783-2 (for vol.7). p. 48

Sources

External links