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Rodents

Rodents are an order of mammals. They have only one pair of incisors in the upper and lower jaws and like to gnaw on hard objects. Rodents are generally small, most of them are active at night or at dawn and dusk, and many species have strong reproductive capacity. Rodents account for about 40% to 50% of mammals. They can be said to be the most successful branch in the evolution of vertebrates. The number of individuals far exceeds the total number of all other groups. They are almost everywhere in the world except Antarctica and a few islands.


I. Introduction to Rodentia

1. General Characteristics:

  • Specialized Incisors: Rodents are characterized by a single pair of continuously growing, chisel-shaped incisors in both the upper and lower jaws. The enamel is typically only present on the front surface, keeping the edge sharp through the animal’s gnawing activities.

  • Reduced Dentition: Between the incisors and cheek teeth (premolars and molars), there is a conspicuous toothless gap (diastema). No canine teeth are present.

  • Dietary Diversity: Most rodents are herbivorous or omnivorous, feeding on seeds, nuts, fruits, leaves, and sometimes insects.

  • Global Distribution: Rodents are found almost everywhere on Earth except Antarctica, inhabiting a broad range of environments—from cold tundra to tropical rainforests, deserts, and grasslands.

2. Diversity and Abundance:

  • Rodentia is the largest order of mammals, comprising about 40% of all mammalian species. Over 2,500 rodent species have been described, illustrating their remarkable evolutionary success and adaptive radiation.


II. Evolutionary History

1. Origins and Fossil Record:

  • Rodents likely originated in the late Paleocene to early Eocene (approximately 56 million years ago). Early fossil rodents appear around the same time as early primates.

  • The Eocene saw the initial diversification and geographic spread of rodents.

2. Geographic Radiation:

  • Rodents dispersed across continents via land bridges and continental drift. Over millions of years, they adapted to diverse habitats, leading to remarkable variety: from burrowing naked mole-rats in Africa to tree-dwelling squirrels, semi-aquatic beavers, and jumping jerboas in arid regions.

3. Paleogene and Neogene Proliferation:

  • By the Oligocene and Miocene, many modern rodent families had emerged, setting the stage for today’s global distribution and immense diversity.


III. Classification Overview

The taxonomy of Rodentia is complex and continually refined. The traditional classification relies heavily on jaw and skull morphology and muscular arrangements. Below is a commonly referenced framework, which may differ slightly from more recent molecular-based classifications. It includes major suborders and families, with some representative genera or species.

Order Rodentia

SuborderSuperfamilyFamilyRepresentative Genera/Species
Sciuromorpha-Aplodontiidae (Sewellel)Mountain beaver (Aplodontia rufa)

-Sciuridae (Squirrels)Squirrels (Sciurus), Chipmunks (Tamias), Marmots (Marmota)

-Gliridae/Myoxidae (Dormice)Garden dormouse (Eliomys), Forest dormouse (Dryomys)
Castorimorpha-Castoridae (Beavers)North American beaver (Castor canadensis), Eurasian beaver (Castor fiber)

-Geomyidae (Pocket gophers)Geomys, Thomomys

-Heteromyidae (Kangaroo rats & relatives)Kangaroo rats (Dipodomys), Pocket mice (Perognathus)
Anomaluromorpha-Anomaluridae (Scaly-tailed squirrels)Scaly-tailed flying squirrels (Anomalurus)

-Pedetidae (Springhares)Springhare (Pedetes capensis)
MyomorphaDipodoidea (Jerboas & allies)Dipodidae (Jerboas)Jerboas (Jaculus), Birch mice (Sicista)

Muroidea (Mice, Rats, Hamsters, Voles)Platacanthomyidae (Spiny dormice)Spiny dormice (Platacanthomys)


Spalacidae (Mole-rats, Bamboo rats)Blind mole-rats (Spalax), Bamboo rats (Rhizomys)


Calomyscidae (Mouse-like hamsters)Mouse-like hamsters (Calomyscus)


Nesomyidae (African rodents)African giant pouched rats (Cricetomys), Rock mice (Petromyscus)


Cricetidae (Hamsters, New World voles & mice)Golden hamster (Mesocricetus auratus), Deer mouse (Peromyscus), Vole (Microtus)


Muridae (True mice, rats, gerbils)House mouse (Mus musculus), Brown rat (Rattus norvegicus)
Hystricomorpha-Ctenodactylidae (Gundis)Gundi (Ctenodactylus)

-Diatomyidae (Laotian rock rat)Laotian rock rat (Laonastes aenigmamus)

-Bathyergidae (African mole-rats)Naked mole-rat (Heterocephalus glaber)

-Hystricidae (Old World porcupines)African porcupine (Hystrix), Indian porcupine (Hystrix indica)

-Petromuridae (Dassie rat)Dassie rat (Petromus)

-Thryonomyidae (Cane rats)Cane rat (Thryonomys swinderianus)

-Erethizontidae (New World porcupines)North American porcupine (Erethizon dorsatum)

-Chinchillidae (Chinchillas & viscachas)Chinchilla (Chinchilla), Viscacha (Lagidium)

-Dinomyidae (Pacarana)Pacarana (Dinomys branickii)

-Caviidae (Guinea pigs, Capybaras)Guinea pig (Cavia), Capybara (Hydrochoerus hydrochaeris)

-Dasyproctidae (Agoutis)Agouti (Dasyprocta)

-Cuniculidae (Pacas)Paca (Cuniculus paca)

-Ctenomyidae (Tuco-tucos)Tuco-tucos (Ctenomys)

-Octodontidae (Degus and allies)Degu (Octodon), Coruro (Spalacopus)

-Abrocomidae (Chinchilla rats)Abrocoma (Chinchilla rat)

-Echimyidae (Spiny rats)Spiny rats (Echimys), Spiny mice (Proechimys)

-Myocastoridae (Nutria)Nutria (Myocastor coypus)

-Capromyidae (Hutias)Hutias (Capromys, Geocapromys)

IV. Summary

Rodents exemplify one of the most successful mammalian radiations, showcasing extensive ecological and morphological diversity. Originating in the Paleocene-Eocene, they spread worldwide, occupying niches from subterranean habitats (mole-rats) to arboreal canopies (squirrels), from aquatic environments (beavers) to grassland ecosystems (marmots, prairie dogs). Their unparalleled adaptability, prolific reproduction, and dental specialization have secured their dominant position as the most species-rich order of mammals.

Carnivora Primates Rodents Chiroptera Eulipotyphla Ungulata Cetacea Lagoiformes Pangolins Proboscidea Monotremata
Meriones meridianus

Meriones meridianus

Meriones meridianus,Yellow rat, noon gerbil, midday gerbil

Rodents LC

Features:The color of the body hair varies greatly, ranging from sandy yellow to dark brown. The tail hair is brownish yellow above and below, with long black or dark brown hair near the tail tip.

Merionis meridianus is a gerbil unique to my country, belonging to the Gerbillinae subfamily. The species-level classification status is stable, with many subspecies, 15 in total. At least 7 subspecies have been described in China, but whether they are all valid needs further study. It mainly lives...

Meriones erythrourus

Meriones erythrourus

Meriones erythrourus,,Meriones libycus,Red-tailed gerbil

Rodents LC

Features:It has a large and sturdy body, a gray-brown back, a gray hair base, a tail that is nearly the same length as the body, and the color of the tail is obviously different from the back color, being brown-yellow.

Red-tailed gerbils belong to the Gerbillinae subfamily. The species-level classification status is stable, and there are many subspecies, up to 15. Xinjiang is the eastern edge of the distribution of red-tailed gerbils. It is a common species in desert oases, often cohabiting with giant gerbils (<...

Brachiones przewalskii

Brachiones przewalskii

Brachiones przewalskii,Short—eared gerbil,Short-eared mouse

Rodents LC

Features:The ears are small, the back of the body is light sandy brown, and the base of the hair is gray.

Short-eared gerbils belong to the Gerbillinae subfamily. This genus has only one species, which is only distributed in China. The species-level taxonomic unit is stable, with 3 subspecies. It is an important member of the desert ecosystem, but the number is small, there is little research on it, and...

Phodopus roborovskii

Phodopus roborovskii

Phodopus roborovskii,Roborovsky hamster, desert hairy rat, bean rat, and mother-in-law rat

Rodents LC

Features:It is the smallest species in the hamster subfamily and has a characteristic short tail.

Phodopus roborovskii is a species of the genus Phodopus in the subfamily Cricetinae. The origin of the species is Nanshan in Inner Mongolia, China. The species-level classification status is stable, with 3 synonyms, one of which (<P. r. przewalskii>) is sometimes listed as a species, and somet...

Phodopus campbelli

Phodopus campbelli

Phodopus campbelli,Campbell's desert hamster,Campbell hamster, first-line hamster

Rodents LC

Features:The hairy-footed hamster is the smallest group in the subfamily of hamsters, and its main identifying feature is its very short tail.

Campbell's hairy-footed mouse belongs to the subfamily Cricetinae. Hairy-footed mouse is the smallest group in the subfamily Cricetinae. Its main identification feature is that its tail is very short, less than 14mm, and the soles of its feet are covered with dense hair. The tail length of other...

Cricetulus migratorius

Cricetulus migratorius

Cricetulus migratorius,Grey hamster,Hamster, moving

Rodents LC

Features:The body is relatively stout. The tail is long, which is longer than the hind legs and is about 30% of the body length. The snout is blunt and the ears are round.

The gray hamster belongs to the subfamily Cricetinae. The taxonomic status of this species is stable, and there are many subspecies, 15 of which are described, 3 of which are in China. It is a species with strong adaptability. According to records (Luo Zexun et al., 2000), this species is distribute...

Cricetulus kamensis

Cricetulus kamensis

Cricetulus kamensis,Tibetan hamster,Kangzang hamster, Tibetan hamster, short-tailed Tibetan hamster, Ladakh hamster

Rodents LC

Features:It has small eyes, large, round ears, a long tail, and a dark gray-brown back. The base of the dorsal hair is light gray-black, gradually darkening from front to back.

Kangzang hamster belongs to the subfamily Cricetinae. Its former Chinese name was Tibetan hamster. Its taxonomic status is stable, but there are many subspecies. It was later revised by Wang Song and Zheng Changlin (1973) to have 4 subspecies in China. It is a plateau species, living in alpine shrub...

Cricetulus barabensis

Cricetulus barabensis

Cricetulus barabensis,Spotted hamster, patterned hamster, moving hamster, cheeked hamster, Chinese hamster

Rodents LC

Features:Small in size, stout and short in appearance, with a relatively round head, a short and blunt snout, and short and round ears with white edges.

The black-lined hamster belongs to the subfamily Cricetinae. The taxonomic status of this species is stable, but the subspecies are relatively confusing. There are as many as 6 subspecies in my country. Whether they are all valid needs further study. It is a common species in the arid and semi-arid...

Ondatra zibethicus

Ondatra zibethicus

Ondatra zibethicus,Muskrat, Ondatra,Castor zibethicus Linnaeus,Blue-rooted marten, muskrat, water rat, water rat

Rodents LC

Features:It is the largest in the subfamily of voles. The male secretes muskrat scent through the muskrat glands in its reproductive system, which has a strong aroma. Muskrat scent can replace musk as a precious Chinese medicinal material and is also a raw material for making high-end perfumes.

Muskrat is commonly known as blue-rooted marten or muskrat. It is named because the glands in its perineum can produce musk-like secretions. Because they live in water and are good at swimming, they are also called water rats or water mice. Muskrat is native to North America and was introduced to th...

Proedromys liangshanensis

Proedromys liangshanensis

Proedromys liangshanensis,Neodon nyalamensis,Vole, Microtus gross

Rodents LC

Features:Its body shape is similar to that of a vole, but it is slightly larger than an ordinary vole, and its ears are smaller and hidden in the fur.

Liangshan Grooved Vole belongs to the subfamily Arvicoliniae. It is a new species published by Liu Shaoying et al. (2007). There was only one species in the genus Proedromys: Proedromys bedfordi, and it was rare. Except for the Sichuan Academy of Forestry, there are only three specimens in the world...

Ellobius talpinus

Ellobius talpinus

Ellobius tancrei,Ellobius talpinus,Flip rat, ground rat, blind rat, arch rat

Rodents LC

Features:It is a species highly adapted to underground life.

Mole voles belong to the subfamily Arvicolinae. There are 5 species in the world and only 1 species in China. The species-level classification status is stable, and the subspecies are very differentiated. China has 3 subspecies recorded. It is a typical grassland underground rodent. It hardly moves...

Eolagurus luteus

Eolagurus luteus

Eolagurus luteus,Lagurus luteus,Yellow Steppe Lemming,Yellow prairie lemming,

Rodents LC

Features:They are large, stocky, and resemble lemmings.

The yellow rabbit-tailed rat is a typical semi-desert steppe species and is cold-resistant. It was once classified as the genus <Lagurus>. Gromov & Polyakov (1992) separated the two from the morphology, making <Eolagurus> an independent genus, but whether the independent genus status...

Microtus oeconomus

Microtus oeconomus

Microtus oeconomus,Root Vole

Rodents LC

Features:The ears are short, the tail is very short, the body hair is fluffy, and the body hair is dark gray-brown or even black-brown.

Root voles are very tolerant of moisture, and their population is large in very humid valley wetlands that are submerged even with a slight rise in water. They are harmful to grassland and wetland ecosystems. In terms of classification, they have long been confused with the Qaidam root vole (Microtu...

Alexandromys limnophilus

Alexandromys limnophilus

Alexandromys limnophilus,Microtus,Root Vole subspecies qaidam,Microtus oeconomus limnophilus

Rodents LC

Features:The body hair is fluffy, and the hair on the back is dark gray-brown or even black-brown.

Qaidam root voles live in caves, which are relatively simple and mostly have a single entrance. They build their nests under haystacks, grass roots, and tree roots. Some individuals build outer nests. They feed on the green parts of plants, and in winter they dig up roots, tuber sprouts, and seeds o...

Lasiopodomys (Stenocranius) gregalis

Lasiopodomys (Stenocranius) gregalis

Lasiopodomys (Stenocranius) gregalis,Lasiopodomys gregalis,Social Vole

Rodents LC

Features:The tail is short, the ears are short, and the back hair comes in various colors such as gray sandy yellow, black brown, brown, and light brown.

Narrow-headed voles live in groups. They are active mainly during the day, but also at night. They are often dispersed in summer, but gather on sunny slopes and leeward places in autumn and winter. The range of activity is generally no more than 150m. The intensity of activity is related to the temp...

Microtus fortis

Microtus fortis

Microtus fortis,Reed Vole,Swamp vole, Far Eastern vole, Giant vole

Rodents LC

Features:The individual is large and is one of the largest individuals in the genus vole.

The oriental vole is a typical burrowing type. It does not hibernate and moves out of its burrows day and night. Due to its frequent activities and frequent trips between several groups of burrows, very obvious runways are often formed on the ground. Especially in moss and reed fields, the runways a...

Garrulax formosus

Garrulax formosus

Garrulax formosus,Red-winged Laughingthrush

Rodents LC

Features:The snout is short and blunt, the ears are short and small, and the tail is very short.

Common voles belong to the subfamily Arvicolinae. There is no dispute about their taxonomic status. However, there are many subspecies, more than 20, which is quite confusing. The one distributed in my country may belong to the Altai subspecies (<M. arvalis obscurus>). It is harmful to farmlan...

Phaiomys leucurus

Phaiomys leucurus

Phaiomys leucurus,Pitymys leucurus,Brandt's pine vole, Pine vole, Pine vole、Blyth's vole

Rodents LC

Features:It has a very short tail, very short ears, and short limbs. It is a species of the genus M. suspensor that is good at digging.

The white-tailed pine vole belongs to the subfamily of voles (Arvicolinae). The previous classification status was very confusing, but Liu Shaoying et al. (2012, 2017) confirmed that it belongs to the genus Arvicolinae through molecular systematic research. This species is distributed at high altitu...

Neodon irene

Neodon irene

Neodon irene

Rodents LC

Features:The fur on the back is gray, and it is the smallest individual in the genus Pine Vole.

Plateau pine voles belong to the subfamily Arvicolinae. The classification status is stable, and it previously included two subspecies: the nominate subspecies (<N. irene irene>) and the Yunnan subspecies (<N. irene forresti>). In-depth research has found that the Yunnan subspecies of pi...

Eothenomys miletus

Eothenomys miletus

Eothenomys miletus,Eothenomys miletus confinii,Eothenomys miletus miletus,Asiatic velvet mouse

Rodents LC

Features:It is small, short and thick, with short limbs and tail. The back of the body is dark reddish brown, and the belly is blue-gray or gray.

The large woolly rat belongs to the subfamily Arvicolinae. Its classification and identification have long been confusing, and the black-bellied woolly rat (Eothenomys melanogaster) is often included as a subspecies. The identification characteristics are also confusing due to tooth variation. It wa...

Eothenomys eva

Eothenomys eva

Eothenomys eva(Thomas,1911),Taozhou woolly rat

Rodents LC

Features:The tail is more than half the length of the body, and the back hair is dense and gray.

Gansu woolly rat belongs to the subfamily Arvicolinae. Gansu woolly rat and another species Caryomys inez are both members of the genus Caryomys. In molecular systematics, Caryomys and Eothenomys are closely related. Previously, Caryomys was always a subgenus of Eothenomys. Liu Shaoying et al. (2012...