Earless lizards are two genera of small lizards native to the semiarid and grassland habitats of the Southwestern United States and Mexico. The genus Cophosaurus and the genus Holbrookia are both characterized by having no external ear openings, presumably to prevent sand from entering their bodies as they dig.
Earless lizards typically vary from 3 to 7 in (76 to 178 mm) long. Males tend to be larger than females. The male has two heavy black strips ahead of its hind legs (pictured). The female differs in that she has a black stripe behind each thigh. A pink throat and flanks indicate pregnancy. [1] Earless lizards have two throat folds, large eyes, and 27 or fewer femoral pores. They are also described as having shorter fore legs compared to their hind legs and also rather long toes. [2] Although they are called earless lizards, they are still completely capable of hearing, but their ears do not have an external opening. This feature is useful when they burrow underground without getting soil in their ears. [3]
Earless lizards are most active during daylight; they hibernate during the winter and fall. When approached by a predator, their defense mechanism is raising and wagging their tails. To claim their territory, a combination of lateral body compression, head bobbing, and push-ups is done. Earless lizards are capable of homeostasis to a certain extent. As a feedback to temperature change, they acquire heat by conduction, convection, and radiation. In cooler temperatures, they raise their body temperature by turning their bodies broadside to the sun to absorb heat (infrared radiation). [4] They can also align their bodies to the sun to reduced absorption to reduce body temperature. In warmer temperatures, they decreases their body temperature by conduction, such as climbing a tree to avoid elevated temperature from the ground. [5]
The diet of earless lizards consists of arthropods, such as butterflies, moths, beetles, grasshoppers, insects, and spiders. [6]
The earless lizard has a peculiar defense mechanism coupled to its cold-blooded metabolism. It has a small opening on the top of its head called a "blood sinus", which helps it gain heat quickly during the daytime. However, the blood can also be channeled to the eyes of the lizard when a predator approaches, efficiently spraying [7] the blood onto the predator, giving it enough time to escape.
Mating takes place in spring. Earless lizards lay their eggs between March and August, and about fifty days are needed for them to hatch. They tend to lay one to three clutches of eggs. Clutch sizes range from one to 10 eggs. When hatched, the hatchlings are about 2 in (5 cm) long.
No major existential threat has been identified in the US or Mexico, but habitat loss and degradation would result in a decline of this species. [8]
Earless lizards are found from the Southwestern and Central United States, in Texas, Arizona, New Mexico, Utah, Colorado, Kansas, Oklahoma, and as far north as Nebraska, South Dakota, and Wyoming. They are also found in Mexico, in the states of Sonora, Chihuahua, Coahuila, Sinaloa, Durango, Zacatecas, San Luis Potosí, Nuevo León, Tamaulipas, and Veracruz.
Lizard is the common name used for all squamate reptiles other than snakes, encompassing over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The grouping is paraphyletic as some lizards are more closely related to snakes than they are to other lizards. Lizards range in size from chameleons and geckos a few centimeters long to the 3-meter-long Komodo dragon.
The emu is a species of flightless bird endemic to Australia, where it is the tallest native bird. It is the only extant member of the genus Dromaius and the third-tallest living bird after its African ratite relatives, the common ostrich and Somali ostrich. The emu's native ranges cover most of the Australian mainland. The Tasmanian, Kangaroo Island and King Island subspecies became extinct after the European settlement of Australia in 1788.
The Phrynosomatidae are a diverse family of lizards, sometimes classified as a subfamily (Phrynosomatinae), found from Panama to the extreme south of Canada. Many members of the group are adapted to life in hot, sandy deserts, although the spiny lizards prefer rocky deserts or even relatively moist forest edges, and the short-horned lizard lives in prairie or sagebrush environments. The group includes both egg-laying and viviparous species, with the latter being more common in species living at high elevations.
The earless monitor lizard is a semiaquatic, brown lizard native to the Southeast Asian island of Borneo. It is the only living species in the family Lanthanotidae and it is related to the true monitor lizards.
The greater earless lizard is the only species in the monotypic genus Cophosaurus. It is closely related to the smaller, lesser earless lizards and other species in the genus Holbrookia, and in fact was placed in that genus and referred to Holbrookia texana from 1852 into the 1970s. Earless lizards lack external ear openings, an adaptation to burrowing in the sand, as are the recessed lower jaw and flared upper labial scales. Greater earless lizards are sexually dimorphic, males grow larger and are more colorful than females, exhibiting pink and green colors that are particularly bright in the breeding season. Two bold black bars mark the lateral region of males but are greatly reduced and vague, or occasionally entirely absent in females.
Phrynosoma, whose members are known as the horned lizards, horny toads, or horntoads, is a genus of North American lizards and the type genus of the family Phrynosomatidae. Their common names refer directly to their horns or to their flattened, rounded bodies, and blunt snouts.
Iphisa is a genus of the lizard family Gymnophthalmidae. The genus is monotypic, meaning that it has only one species, Iphisa elegans, and its common name is the glossy shade lizard. I. elegans is native to the Amazon and is typically found in regions of South America, centrally located in the Amazon Basin. The average body length of the glossy shade lizard is 55 mm. Relatively small, these lizards rely on running as their primary form of movement and, interestingly, exhibit death-feigning behavior, which aids in protection from potential predators.
Holbrookia is a genus of earless lizards, known commonly as the lesser earless lizards, in the family Phrynosomatidae. The genus contains six recognized species, which are found throughout the Southwestern and Central United States and northern Mexico. They are characterized by having no external ear openings, presumably to prevent soil from entering their bodies when they are digging.
The greater short-horned lizard, also commonly known as the mountain short-horned lizard or Hernández's short-horned lizard, is a species of lizard in the family Phrynosomatidae. The species is endemic to western North America. Like other horned lizards, it is often called a "horned toad" or "horny toad", but it is not a toad at all. It is a reptile, not an amphibian. It is one of seven native species of lizards in Canada.
The viviparous lizard, or common lizard, is a Eurasian lizard. It lives farther north than any other species of non-marine reptile, and is named for the fact that it is viviparous, meaning it gives birth to live young. Both "Zootoca" and "vivipara" mean "live birth", in (Latinized) Greek and Latin respectively. It was called Lacerta vivipara until the genus Lacerta was split into nine genera in 2007 by Arnold, Arribas & Carranza.
Xenosaurus grandis, commonly known as the knob-scaled lizard, is a species of diurnal, terrestrial lizard endemic to Mexico and Guatemala. It primarily inhabits tropical rainforests. It dwells in rock crevices and eats insects.
The mountain plover is a medium-sized ground bird in the plover family (Charadriidae). It is misnamed, as it lives on level land. Unlike most plovers, it is usually not found near bodies of water or even on wet soil; it prefers dry habitat with short grass and bare ground. Its height is in the range of 5-9 inches, and length in the range of 8-10 inches ; and it weighs around 102 grams.
Holbrookia maculata, commonly known as the lesser earless lizard, is a species of lizard in the family Phrynosomatidae. The species is native to the southwestern and central United States and northern Mexico. There are eight recognized subspecies.
The Mexican mole lizard, also commonly known as the five-toed worm lizard, or simply as Bipes, is a species of amphisbaenian in the family Bipedidae. The species is endemic to the Baja California Peninsula. It is one of three species of amphisbaenians that have legs.
The western banded gecko is a species of lizard in the family Eublepharidae. The species is native to the southwestern United States and adjacent northwestern Mexico. Five subspecies are recognized.
The regal horned lizard is a horned lizard species native to Mexico and the Southwest United States.
The gibber earless dragon also known as the smooth-snouted earless dragon, is a species of agamid lizard endemic to Australia. It is one of a documented species of the genus Tympanocryptis, a group of small terrestrial lizards that feed off invertebrates and are characterised by the absence of an external ear structure.
The barred wedge-snout ctenotus is a species of skink found in Australia.[2]
Anolis gundlachi, also commonly known as the yellow-chinned anole, Gundlach's anole, and the yellow-beard anole, is an oviparous, sexually dimorphic species of lizard in the family Dactyloidae. The species is endemic to Puerto Rico and lives in mountainous forests at high elevations. The diet of A. gundlachi consists mostly of insects. This species is also known for signaling other lizards through a modulated head bob display, with varying bobbing amplitudes and patterns based on an individual's distance from other lizards.