''Polydaedalus'', commonly referred as African monitors, is one of the 11

subgenera In biology, a subgenus (plural: subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between t ...

of the genus '' Varanus''. Its species are native to

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

and

West Asia Western Asia, West Asia, or Southwest Asia, is the westernmost subregion of the larger geographical region of Asia, as defined by some academics, UN bodies and other institutions. It is almost entirely a part of the Middle East, and includes Ana ...

, among which are some of the World's largest

lizards Lizards are a widespread group of squamate reptiles, with over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic since it excludes the snakes and Amphisbaenia althou ...

Description

African monitors are typically medium-sized monitor lizards, with males being larger than females. Nile monitors usually measure in length and weighs around , with exceptionally large specimens exceeding in length and in mass, making it the World's fourth largest lizard after the

Komodo dragon The Komodo dragon (''Varanus komodoensis''), also known as the Komodo monitor, is a member of the monitor lizard family Varanidae that is endemic to the Indonesian islands of Komodo, Rinca, Flores, and Gili Motang. It is the largest extant ...

Asian water monitor The Asian water monitor (''Varanus salvator'') is a large varanid lizard native to South and Southeast Asia. It is one of the most common monitor lizards in Asia, ranging from coastal northeast India, Bangladesh, Sri Lanka, mainland Southeast A ...

and

Crocodile monitor ''Varanus salvadorii'', also known as the crocodile monitor, Papuan monitor and Salvadori's monitor, is a species of monitor lizard endemic to New Guinea. It is the largest monitor lizard known from New Guinea, and is one of the longest lizard ...

. The

Rock monitor The rock monitor (''Varanus albigularis'') is a species of monitor lizard in the family Varanidae. The species is endemic to Central, East, and southern Africa. It is the second-longest lizard found on the continent, and the heaviest-bodied; lo ...

is much bulkier and is larger on average, but has a slightly smaller maximum size of just more than long but still weighing over , rivalling the

Perentie The perentie (''Varanus giganteus'') is the largest monitor lizard or goanna native to Australia. It is one of the largest living lizards on earth, after the Komodo dragon, Asian water monitor, crocodile monitor, and intersecting by size with Ni ...

as the fifth in size. African monitors are characterized by their tall heads and nostrils positioned close to their eyes. Their jaws are short and equipped with round, thick teeth. African have long, muscular tails like all monitors.

Evolution and ecology

The genus '' Varanus'' is believed to have originated in

South Asia South Asia is the southern subregion of Asia, which is defined in both geographical and ethno-cultural terms. The region consists of the countries of Afghanistan, Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan, and Sri Lanka.;;;;;;;; ...

, and the anatomy of its earliest members are thought to resemble modern members of '' Empagusia'', such as the

Bengal monitor The Bengal monitor (''Varanus bengalensis''), also called the common Indian monitor, is a monitor lizard distributed widely in the Indian Subcontinent, as well as parts of Southeast Asia and West Asia. This large lizard is mainly a terrestrial a ...

. Other monitors spread across the

Old World The "Old World" is a term for Afro-Eurasia that originated in Europe , after Europeans became aware of the existence of the Americas. It is used to contrast the continents of Africa, Europe, and Asia, which were previously thought of by the ...

in two directions: true monitors (subgenus '' Varanus''), tree monitors (subgenus ''

Hapturosaurus The subgenus ''Hapturosaurus,'' sometimes known as the tree monitors, consists of slender-bodied arboreal monitor lizards mostly found in the tropical rainforests of Indonesia and Papua New Guinea. Taxonomy The type species is the green tree ...

'') and dwarf monitors (subgenus ''

Odatria The subgenus ''Odatria'', sometimes known as the dwarf monitor lizards, consists of small monitor lizards found in Australia and Indonesia. Species in this subgenus include the smallest monitor species in the world, the tiny 16 gram Dampier Peni ...

'') moved east towards

Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical United Nations geoscheme for Asia#South-eastern Asia, south-eastern region of Asia, consistin ...

and

Oceania Oceania (, , ) is a region, geographical region that includes Australasia, Melanesia, Micronesia, and Polynesia. Spanning the Eastern Hemisphere, Eastern and Western Hemisphere, Western hemispheres, Oceania is estimated to have a land area of ...

, quickly diversifying into different niches. Meanwhile, desert monitors (subgenus '' Psammosaurus'') and african monitors (subgenus ''Polydaedalus'') moved west towards

Central Asia Central Asia, also known as Middle Asia, is a subregion, region of Asia that stretches from the Caspian Sea in the west to western China and Mongolia in the east, and from Afghanistan and Iran in the south to Russia in the north. It includes t ...

, the

Middle East The Middle East ( ar, الشرق الأوسط, ISO 233: ) is a geopolitical region commonly encompassing Arabian Peninsula, Arabia (including the Arabian Peninsula and Bahrain), Anatolia, Asia Minor (Asian part of Turkey except Hatay Pro ...

and

, developing a corporal built that is suited for a diet in a dry region: tall skulls and round teeth can crush shells of

invertebrates Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

easily, and caudally positioned nostrils can help them avoid breathing sand particles in the air while travelling through dry and dusty areas, such as

deserts A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to denudation. About one ...

. Despite so, the Nile monitor, living in the

Nile Basin The Nile Basin is the part of Africa drained by the Nile River and its tributaries. Besides being the second largest hydrographic basin in Africa, the Nile Basin is effectively the most notable drainage basin on the continent. It covers approxim ...

with a rich resource of freshwater, has adapted a

piscivorous A piscivore () is a carnivorous animal that eats primarily fish. The name ''piscivore'' is derived . Piscivore is equivalent to the Greek-derived word ichthyophage, both of which mean "fish eater". Fish were the diet of early tetrapod evoluti ...

diet, feeding mostly on fish. The Rock monitor, being large and able to swallow large prey, often seek chances to eat turtles, which contributes most of its vertebrate food. African monitors thrive throughout the African continent. Nile monitors are the largest lizards in Africa, having a population of over 4 million widely distribued across

Sub-Sahara Sub-Saharan Africa is, geographically, the area and regions of the continent of Africa that lies south of the Sahara. These include West Africa, East Africa, Central Africa, and Southern Africa. Geopolitically, in addition to the African co ...

in all habitats but

. Rock monitors are also abundant, having 4 subspecies and a combined population in the millions.

References

{{taxonbar, from=Q21439243 Animal subgenera Monitor lizards