Sauria


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Sauria

[′sȯr·ē·ə]
(vertebrate zoology)
The lizards, a suborder of the Squamata, characterized generally by two or four limbs but sometimes none, movable eyelids, external ear openings, and a pectoral girdle.

Sauria

 

(lizards), a suborder (or order) of reptiles of the order (or subclass) Squamata. The body length varies from 3.5 cm to 3 m (Komodo dragon).

The trunk of saurians is spindle-shaped, flattened, laterally compressed, or cylindrical. Some have well-developed extremities with five digits; others lack extremities, in which case the trunk is snakelike. In the majority, the eyelids are movable; in some, they are fixed and transparent or hidden beneath the skin. The teeth have one or several cusps and are attached to the inner surface of the jaws (pleurodont) or to the edges (acrodont); the former are not replaced when they wear out, while the latter are. In the Helodermatidae (poisonous lizards), the curved conical teeth have longitudinal grooves, along which the poison flows into the bite wound. The vertebrae in most are procoelous; in a number of gekkonids they are amphicoelous. In gekkonids and agamids the tongue is broad and fleshy. In the varanids it is long and partially forked and can be retracted into a special sheath. In chameleons, it is very long and thickened at the tip. Many saurians have a parietal foramen. The skin is covered with ceratinous scales, and often there are horny outgrowths, nodules, and spines. Some saurians are capable of autotomy of the tail.

There are about 3,500 extant species, which are grouped into 20 families, including Gekkonidae, Pygopodidae, Iguanidae, Agamidae, Chamaeleontidae, Scincidae, Lacertidae, Cordylidae, and Helodermatidae (seeGECKOS; PYGOPODIDAE; IGUANIDAE; AGAMA; CHAMAELEONTIDAE; SCINCIDAE; CORDYLIDAE; and HELODER MATIDAE). They are distributed throughout the world, except the frigid zones. A number of species are found in mountains as far as the snow line. There are 77 species in the USSR.

The majority of saurians are terrestrial, sometimes climbing shrubs or trees or burrowing into the sand (Phrynocephalus and others). Some live in trees and are capable of gliding flight. A number of gekkonids and agamids can climb up vertical surfaces, such as cliffs. Some saurians live in the soil, in which case the eyes are usually absent and the body is elongated. The marine iguana lives along the coast and often enters the water. Some saurians are diurnal, while others are nocturnal; the latter have slitlike pupils. The majority feed mainly on insects and their larvae, as well as on spiders, mollusks, worms, and other invertebrates; occasionally they feed even on small vertebrates.

Most saurians are oviparous; some are ovoviviparous and some even viviparous. Saurians usually lay one to 35 eggs, which are enclosed in a soft, leathery, parchment-like shell; only in gekkonids, except a few ovoviviparous species, are they covered with a hard calcareous shell. Some species lay eggs three or four times a year. Embryos of oviparous species develop an egg tooth. Saurians lay their eggs in the sand, under rocks, and in other such places. In ovoviviparous species the young develop by feeding on the nutrient matter of the egg in the mother’s body and emerge from the egg after it is laid. In viviparous species, such as some skinks, the embryo is nourished by the mother’s body through a false placenta. Parthenogenesis is observed in a number of species, and in such species males are usually unknown. Sexual maturity is usually achieved the year after hatching; in some species it is achieved later (for example, in the Komodo dragon in the fifth year).

In the narrower sense of the word, only members of the family Lacertidae (true lizards), which includes 30 genera with 170 species, should be called lizards. They are distributed in Europe, Africa (except Madagascar), and Asia. The genus Lacerta, which includes about 40 species, belongs to the family; the USSR has 12 species.

Saurians are useful animals, since they eat insects that are harmful to agriculture. The flesh of large lizards is used as food by the local inhabitants, and the skins are used to make various products.

REFERENCES

Zhizn’ zhivotnykh, vol. 4, part 2. Moscow, 1969.
Prytkaia iashcheritsa. Moscow, 1976.
Opredelitel’ zemnovodnykh i presmykaiushchikhsia fauny SSSR. Moscow, 1977.
Smith, H. M. Handbook of Lizards. Ithaca-New York, 1946.
Bellairs, A. The Life of Reptiles, vols. 1–2. New York, 1970.

I. S. DAREVSKII

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Especies Comunidad Vegetal Pinus Pinus Pseudotsuga ayacahuite pseudostrobus menziesii Amphibia: anura Spea multiplicata X Amphibia: caudata Chiropterotriton priscus X X X Squamata: Sauria Barisia ciliaris X X Sceloporus grammicus X X disparilis Sceloporus minor X X Plestiodon brevirostris X X pineus Squamata: Serpentes Crotalus pricei miquihuanus Especies Comunidad Vegetal Pinus Pinus Pinus hartwegii strobiformis culminicola Amphibia: anura Spea multiplicata Amphibia: caudata Chiropterotriton priscus X X Squamata: Sauria Barisia ciliaris X X Sceloporus grammicus X X disparilis Sceloporus minor X X Plestiodon brevirostris X pineus Squamata: Serpentes Crotalus pricei X miquihuanus Cuadro 2.
oaxacae (Mertens 1930) Pr E REPTILIA SQUAMATA SAURIA Anguidae Abronia ochoterenai (Martin del Campo 1939) Pr E X A.