Agamidae
Encyclopedia
Agamids, lizards of the family
Agamidae, include more than 300 species in Africa
, Asia
, Australia
, and a few in Southern Europe
. Many species are commonly called dragons or dragon lizards. Phylogenetically
they may be sister to the Iguanidae
, and have a similar appearance. Agamids usually have well-developed, strong legs. Their tails cannot be shed and regenerated like those of geckoes, though a certain amount of regeneration is observed in some. Many agamid species are capable of limited change of their colours to regulate their body temperature. In some species, males are more brightly coloured than females and colours play a part in signaling and reproductive behaviours. Although agamids generally inhabit warm environments, ranging from hot desert
s to tropical rainforest
s, at least one species, the Mountain Dragon
, is found in cooler regions.
This group of lizards includes some more popularly known, such as the domesticated bearded dragon and the uromastyx
.
One of the key distinguishing features of the agamids is their teeth, which are borne on the outer rim of the mouth (acrodont
), rather than on the inner side of the jaws (pleurodont
). This feature is shared with the chameleon
s, but is otherwise unusual among lizards. Agamid lizards are generally diurnal, with good vision, and include a number of arboreal species, in addition to ground and rock-dwellers. They generally feed on insects and other arthropod
s (such as spiders), although some larger species may include small reptiles or mammals, nestling birds, flowers or other vegetable matter in their diets. The great majority of agamid species are oviparous.
.
The agamids show a curious distribution. They are found over much of the Old World
, including continental Africa
, Australia
, Southern Asia
and sparsely in warmer regions of Europe
. They are however absent from Madagascar
and from the New World
. The distribution is the opposite of that of the iguanids
, who are found in just these areas but absent in areas where agamids are found. A similar faunal divide is found in between the boas and pythons.
The chameleon
s of the sister family Chamaeleonidae are sometimes discussed as subfamily Chamaeleoninae and subfamily Agaminae (referring to Agamidae, not the Agaminae mentioned above).
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Agamidae, include more than 300 species in Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
, Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, and a few in Southern Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
. Many species are commonly called dragons or dragon lizards. Phylogenetically
Phylogenetics
In biology, phylogenetics is the study of evolutionary relatedness among groups of organisms , which is discovered through molecular sequencing data and morphological data matrices...
they may be sister to the Iguanidae
Iguanidae
Iguanidae is a family of lizards, composed of iguanas and related species.-Classification of Iguanidae:Two different classification schemes have been used to define the structure of this family. These are the "traditional" classification and the classification presented by Frost et al. .Frost et...
, and have a similar appearance. Agamids usually have well-developed, strong legs. Their tails cannot be shed and regenerated like those of geckoes, though a certain amount of regeneration is observed in some. Many agamid species are capable of limited change of their colours to regulate their body temperature. In some species, males are more brightly coloured than females and colours play a part in signaling and reproductive behaviours. Although agamids generally inhabit warm environments, ranging from hot desert
Desert
A desert is a landscape or region that receives an extremely low amount of precipitation, less than enough to support growth of most plants. Most deserts have an average annual precipitation of less than...
s to tropical rainforest
Rainforest
Rainforests are forests characterized by high rainfall, with definitions based on a minimum normal annual rainfall of 1750-2000 mm...
s, at least one species, the Mountain Dragon
Mountain dragon
The Mountain Dragon is an agamid, or dragon lizard, endemic to Australia. It occurs in the uplands of New South Wales and Victoria, as well as in Tasmania where it is the only native agamid. Mountain dragons are found in dry woodlands and heaths with access to open areas for sunning themselves...
, is found in cooler regions.
This group of lizards includes some more popularly known, such as the domesticated bearded dragon and the uromastyx
Uromastyx
The Uromastyx is a genus of lizard whose members are better-known as Spiny-tailed lizards, uromastyxes, mastigures, or dabb lizards. Uromastyx are primarily herbivorous, but occasionally eat insects, especially when young. They spend most of their waking hours basking in the sun, hiding in...
.
One of the key distinguishing features of the agamids is their teeth, which are borne on the outer rim of the mouth (acrodont
Acrodont
Acrodont is a formation of the teeth whereby the teeth are consolidated with the summit of the alveolar ridge of the jaw without sockets. The term also refers to species of reptiles that have such a formation. This formation is common in the order Squamata, with the only other teeth formation in...
), rather than on the inner side of the jaws (pleurodont
Pleurodont
Pleurodont is a formation of the teeth that are fused by their sides to the inner surface of the jaw bones.This formation is common in the order Squamata.-External links:* *...
). This feature is shared with the chameleon
Chameleon
Chameleons are a distinctive and highly specialized clade of lizards. They are distinguished by their parrot-like zygodactylous feet, their separately mobile and stereoscopic eyes, their very long, highly modified, and rapidly extrudable tongues, their swaying gait, the possession by many of a...
s, but is otherwise unusual among lizards. Agamid lizards are generally diurnal, with good vision, and include a number of arboreal species, in addition to ground and rock-dwellers. They generally feed on insects and other arthropod
Arthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
s (such as spiders), although some larger species may include small reptiles or mammals, nestling birds, flowers or other vegetable matter in their diets. The great majority of agamid species are oviparous.
Systematics and distribution
There have been very few studies of the Agamidae with the first comprehensive assessment by Moody (1980) followed by a more inclusive assessment by Frost and Etheridge (1989). Subsequent studies were based on mitochondrial DNA loci (using allozymes), and sampling across the Agamidae. Few other studies focused on clades within the family, but the Agamidae have not been as well investigated as the IguanidaeIguanidae
Iguanidae is a family of lizards, composed of iguanas and related species.-Classification of Iguanidae:Two different classification schemes have been used to define the structure of this family. These are the "traditional" classification and the classification presented by Frost et al. .Frost et...
.
The agamids show a curious distribution. They are found over much of the Old World
Old World
The Old World consists of those parts of the world known to classical antiquity and the European Middle Ages. It is used in the context of, and contrast with, the "New World" ....
, including continental Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, Southern Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
and sparsely in warmer regions of Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
. They are however absent from Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
and from the New World
New World
The New World is one of the names used for the Western Hemisphere, specifically America and sometimes Oceania . The term originated in the late 15th century, when America had been recently discovered by European explorers, expanding the geographical horizon of the people of the European middle...
. The distribution is the opposite of that of the iguanids
Iguanidae
Iguanidae is a family of lizards, composed of iguanas and related species.-Classification of Iguanidae:Two different classification schemes have been used to define the structure of this family. These are the "traditional" classification and the classification presented by Frost et al. .Frost et...
, who are found in just these areas but absent in areas where agamids are found. A similar faunal divide is found in between the boas and pythons.
Subfamilies
Among the Agamidae, six subfamilies are generally recognized:- AgaminaeAgaminaeAgaminae is a subfamily of reptiles in the family Agamidae.-Genera:Listed alphabetically:*Genus Acanthocercus*Genus Acanthosaura – mountain horned dragons*Genus Agama*Genus Amphibolurus*Genus Aphaniotis*Genus Brachysaura...
(Africa, Asia and Australia) - AmphibolurinaeAmphibolurinaeAmphibolurinae is a subfamily of reptiles in the family Agamidae. Members of this subfamily are found in Australia and New Guinea.-Genera:Genera within the subfamily Amphibolurinae include:* Amphibolurus* Arua...
(Australia and New Guinea) - DraconinaeDraconinaeDraconinae is a subfamily of reptiles in the family Agamidae found in southern Asia. Note, some taxonomies believe that these genera belong to the subfamily Agaminae.-Genera:* Acanthosaura – mountain horned dragons* Aphaniotis* Bronchocela...
(South and Southeast Asia) - Hydrosaurinae (Hydrosaurus, Papua New Guinea, Philippines, and Indonesia)
- Leiolepidinae (Leiolepis, Southeast Asia)
- UromasticinaeUromasticinaeUromasticinae is a subfamily of reptiles in the family Agamidae....
(Saara and Uromastyx, Africa and south Asia)
The chameleon
Chameleon
Chameleons are a distinctive and highly specialized clade of lizards. They are distinguished by their parrot-like zygodactylous feet, their separately mobile and stereoscopic eyes, their very long, highly modified, and rapidly extrudable tongues, their swaying gait, the possession by many of a...
s of the sister family Chamaeleonidae are sometimes discussed as subfamily Chamaeleoninae and subfamily Agaminae (referring to Agamidae, not the Agaminae mentioned above).
External links
- Agamidae (all species) at The Reptile Database