Are Kangaroos Rodents


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Kangaroo rats, small rodents of genus Dipodomys, are native to western North America. The common name derives from their bipedal form. They hop in a manner similar to the much larger kangaroo, but developed this mode of locomotion independently, like several other clades of rodents (e.g. dipodids and hopping mice).

Kangaroo rats are four-toed heteromyid rodents with big hind legs, small front legs and relatively large heads. Adults typically weigh between 70 and 170 g.[2] The tails of kangaroo rats are longer than both their bodies and their heads. Another notable feature of kangaroo rats are their fur-lined cheek pouches, which are used for storing food. The coloration of kangaroo rats varies from cinnamon buff to dark gray, depending on the species.[3] There is also some variation in length with one of the largest species, the banner-tailed kangaroo rat being six inches in body length and a tail length of eight inches.[3] Sexual dimorphism exists in all species, with males being larger than females.


Australia's kangaroos are marsupials, a group of mammals defined by the way itsmembers reproduce. Most mammals bear live offspring that developinternally, within a uterus. Marsupials are also born live, but they arebarely past the embryonic state at birth and must complete theirmaturation in an external pouch that contains teats for the infant tonurse. Kangaroos are related to all other marsupials, albeit to variousdegrees.

Macropods

Thekangaroo's closest relatives are wallabies and wallaroos, which areessentially smaller versions of kangaroos. Together they comprise thegenus macropus, one of 11 genera in the taxonomic family macropodidae,which means "big feet" and references one of the universal features ofmarsupials in this category. Macropodidae encompasses a total of 54species, nearly all of which get around by hopping on their enlargedhind feet. An exception is the tree kangaroo, a macropod that climbsinstead of hops and therefore has bigger forelimbs and smaller hindlimbs. Macropods live in Australia, New Guinea and neighboring islands.

Diprotodonts

Atthe next highest level of classification, kangaroos and its fellowmacropods belong to the order diprotodontia, which encompasses 10families and 117 species found in Australia and its vicinity. Likekangaroos, marsupials in this order are overwhelmingly herbivorous andhave two distinguishing features: they are syndactylous, which means thesecond and third toes of their hind feet are fused together, anddiprotodont, meaning they have one pair of incisor teeth on their lowerjaws. The kangaroo's diprodont relatives include some of Australia'sbest known marsupials, such as koalas and wombats, as well as gliders,whose front and hind limbs are attached by a membrane with which they'reable to glide on air. Rat kangaroos, possums and cuscuses are alsodiprotodonts.

Australidelphian Marsupials

Forkangaroos, the next highest level of kinship correlates with geography.Diprodontotia is one of the five taxonomic orders in the superorderAustralidelphia, which encompasses 200 or so species of mammals found inAustralia and New Guinea. The sole exception is the monito del monte ofChile and Argentina, which seems to have more in common with kangaroosand other Australiasian marsupials than with any living species in SouthAmerica. Australidelphian marsupials include carnivorous species suchas the Tasmanian devil and marsupial moles which, like other moles, digunderground burrows.

Metherian Mammals

Some90 million years ago, during the Cretaceous period, mammals that givebirth to live young -- as opposed to the unusual egg-laying mammalspecies collectively known as monotremes -- split into what are nowconsidered two taxonomic infraclasses of mammals: marsupials, ormetherian, and placentals, or etherian. Kangaroos therefore share a deepevolutionary ancestry with all marsupials, including opposums, of theorder didelphimorphia, which are found in the Americas.

Source :

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