Lacertilia

The lacertilians or lizards (Lacertilia) are a paraphyletic group of squamates that includes most of the extant squamates, such as monitor lizards, iguanas, coritophanids, chameleons, lizards, and geckos, as well as some very notable fossil forms, such as Upper Cretaceous mosasaurs. The lacertilians comprise almost 5000 species.

Previously, the suborder formed by lacertilians and snakes was called saurians (Sauria), but since it has turned out to be paraphyletic, the name Sauria is now applied to a largest clade of reptiles that includes most of the diapsids. Formerly they were classified as an independent suborder of snakes and aphisbenians that turned out to be paraphyletic.

Features

They usually have four legs, an externally opening ear, and movable eyelids. The length ranges from a few centimeters in some Caribbean geckos to about 3 meters in the Komodo dragon.

Some species of lizards, called glass snakes or lutions, do not have functional legs, despite having traces of skeletal legs. They are distinguished from true snakes by the presence of tympanic openings and eyelids. Its body is elongated and with a well-developed tail. Lizards in the Scincomorpha family often have bright, iridescent colors that appear wet. But like all other lizards, they have dry skin, generally preferring to avoid water (although all lizards can swim if necessary).

All lizards can change color in response to their environment or in times of danger. The most typical example is the chameleon, but more subtle color changes can also occur in other lizard species.

Some species are capable of breaking off their tail when threatened or captured by a predator; this ability is called autotomy and is due to the presence of special rupture planes of the caudal vertebrae. After autotomy, the tail regenerates, but the new tail is not identical to the lost one; indeed, the vertebrae cannot regenerate and are replaced by a non-segmented cartilaginous tube.

Biology and ecology

Lizards generally feed on invertebrates, terrestrial arthropods are their main diet, and sometimes (depending on the species) on small vertebrates such as certain rodents or insectivores, including other lizard species. A few species are omnivorous and can eat plants. Historically, only one genus, Heloderma, has been considered venomous, which includes the Gila monster (H. suspectum) and the beaded lizard (H. horridum). These species inhabit western Mexico and southern Texas, and have two venom glands in their jaws. However, in 2009 it was discovered that the Komodo dragon (Varanus komodoensis) is possibly also venomous, following the discovery of a pair of venom glands in the lower jaw. However, it is found in Discussion of the real effect it can have after a bite.

Most lizards lay eggs, although a few species retain them inside and give birth directly (ovoviviparous).

Phylogeny

Genetic analyzes have shown that lizards are a paraphyletic taxon representing the early grade of squamous, since snakes (Serpentes) and blind shingles (Amphisbaenia) would originate from different types of lizards. These analyzes have shown that venomous lizards share an ancestor with snakes, a grouping that has been called Toxicofera. Its phylogeny is as follows:

Taxonomy

The following suborders were classified as part of Lacertilia:

Suborden Dibamia

Dibamidae Family

Suborden Iguania

Arretosauridae Family †

Euposauridae Family †

Family Priscagamidae †

Family Isodontosauridae †

Agamidae Gray Family, 1827

Family Chamaeleonidae Rafinesque, 1815

Family Corytophanidae Fitzinger, 1843

Crotaphytidae Smith & Brodie Family, 1982

Family Dactyloidae Fitzinger, 1843

Hoplocercidae Frost & Etheridge, 1989

Family Iguanidae Oppel, 1811

Leiocephalidae Frost & Etheridge, 1989

Leiosauridae Frost & Etheridge, 2001

Liolaemidae Frost & Etheridge, 1989

Family Opluridae Moody, 1983

Family Phrynosomatidae Fitzinger, 1843

Family Polychrotidae Fitzinger, 1843

Tropiduridae Bell Family, 1843

Suborden Gekkota Cuvier, 1817

Family Carphodactylidae Kluge, 1987

Diplodactylidae Underwood, 1954

Eublepharidae Boulenger Family, 1883

Gekkonidae Oppel family, 1811

Phyllodactylidae Gamble, Bauer, Greenbaum & Jackman, 2008

Pygopodidae Boulenger Family, 1884

Sphaerodactylidae Underwood, 1954

Family Bavarisauridae †

Suborden Scincomorpha Camp, 1923

Family Paramacellodidae †

Family Slavoiidae †

Scincidae Gray Family, 1825

Family Cordylidae Mertens, 1937

Family Gerrhosauridae Fitzinger, 1843

Xantusiidae Baird Family, 1858

Mongolochamopidae Family †

Family Adamisauridae †

Subord Laterata

Lacertidae Gray Family, 1825

Teiidae Gray Family, 1827

Gymnophthalmidae Merrem, 1820

Suborden Anguimorpha Cope, 1864

Anguidae Gray, 1825

Family Anniellidae Boulenger, 1885

Diploglossidae Bocourt, 1873

Xenosauridae Cope Family, 1866

Varanidae Hardwicke & Gray, 1827

Lanthanotidae Steindachner, 1877

Helodermatidae Gray, 1837

Mosasauridae Family †

Shinisauridae Ahl family, 1930

Additional bibliography

• Behler, John L.; King, F. Wayne (1979). The Audubon Society Field Guide to Reptiles and Amphibians of North America (in English). New York: Alfred A. Knopf. p. 581. ISBN 978-0-394-50824-5.
• Capula, Massimo; Behler, John L. (1989). Simon & Schuster's Guide to Reptiles and Amphibians of the World (in English). New York: Simon & Schuster. ISBN 978-0-671-69098-4.
• Cogger, Harold; Zweifel, Richard (1992). Reptiles & Amphibians (in English). Sydney: Weldon Owen. ISBN 978-0-8317-2786-4.
• Conant, Roger; Collins, Joseph (1991). A Field Guide to Reptiles and Amphibians Eastern/Central North America (in English). Boston, Massachusetts: Houghton Mifflin Company. ISBN 978-0-395-58389-0. (requires registration).
• Ditmars, Raymond L (1933). Reptiles of the World: The Crocodilians, Lizards, Snakes, Turtles and Tortoises of the Eastern and Western Hemispheres (in English). New York: Macmillan. p. 321.
• Freiberg, Marcos; Walls, Jerry (1984). The World of Venomous Animals (in English). New Jersey: TFH Publications. ISBN 978-0-87666-567-1.
• Gibbons, J. Whitfield (1983). Their Blood Runs Cold: Adventures With Reptiles and Amphibians (in English). Alabama: University of Alabama Press. p. 164. ISBN 978-0-8173-0135-4. (requires registration).
• Greenberg, Daniel A. (2004). Lizards (in English). Marshall Cavendish. ISBN 9780761415800.
• Rosenfeld, Arthur (1987). Exotic Pets (in English). New York: Simon & Schuster. p. 293. ISBN 978-0671636906.