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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
Clethrionomys rutilus

Clethrionomys rutilus

Clethrionomys rutilus,,Myodes rutilus,Northern Red-backed Vole,Clethrionomys rutilus

Rodents LC

Features:The ears are small, the front and hind limbs are short, the tail is densely haired, and the back hair is bright ochre brown or brown-red.

Red-backed voles belong to the subfamily Microtiinae. The species-level classification status is stable, and there are many subspecies differentiations. There are 2 subspecies in China. It is a typical cold-resistant species in the north. The population in meadows and wetlands in coniferous forests...

Clethrionomys rufocanus

Clethrionomys rufocanus

Clethrionomys rufocanus,Myodes rufocanus,Gray Red-backed Vole,Clethrionomys rufocanus,Hypudoeus rufocanus,Red-haired mouse

Rodents LC

Features:It has a stout body, large ears, short limbs, a reddish-brown back, grayish-yellow sides, and dirty white fur on the belly.

The brown-backed croaker belongs to the subfamily Arvicolinae. The species status is very stable, but the genus status is controversial. The species was named in 1846, and Miller (1900) established the subgenus <Craseomys> and regarded the brown-backed croaker as the only species of the subgen...

Alticola stoliczkanus

Alticola stoliczkanus

Alticola stoliczkanus (Blanford,1875)

Rodents LC

Features:The back of the body is gray-brown with a yellow-white spot behind the ear.

Alticola strachyi belongs to the Arvicolinae subfamily. The type specimen is found in Ladakh, India. There is no controversy about the classification itself, but the type locality of another species: Kumaung Alticola (<Alticola strachyi>) is also in Ladakh. The difference between the two class...

Alticola argentata

Alticola argentata

Alticola argentata,Gray Mountain

Rodents LC

Features:The top of the head and back of the body are light brown-gray, with dark gray base and light brown tips; the belly is grayish white, with gray base and white tips.

Belongs to the subfamily Arvicolinae. Its taxonomic status is controversial and is generally considered a synonym of Lowe's alpine croaker (<Alticola roylei>). The subspecies classification is also confusing. All species of the genus Alticola have a relatively limited distribution and hars...

Eospalax smithi

Eospalax smithi

Eospalax smithi,Myospalax smithii,Myospalax smithii Thomas

Rodents LC

Features:It is of medium size, with a short tail and dark gray-brown fur.

The Stevens's zokor belongs to the subfamily Myospalacinae. The Stevens's zokor is named after the specimen collected from Lintan, Gansu. There was controversy over whether it is an independent species. Sometimes it is regarded as a subspecies of the Qinling zokor (Eospalax rufescens). It ma...

Myospalax fontanieri

Myospalax fontanieri

Myospalax fontanieri,Common Chinese zokor,Eospalax fontanieri,Blind mouse, ground mouse, mole

Rodents LC

Features:The body shape is similar to that of the Northeastern zokor, but the front feet and front claws are thinner and shorter. The head is broad and flat, the nose is blunt, the back is obviously rusty red, and the hair base is gray-brown.

The Chinese zokor belongs to the subfamily Myospalacinae. There is much controversy over its classification. It was previously considered to belong to the family Myospalacinae. Since 1997, a number of molecular biological studies have shown that zokor and bamboo rats, as well as the northern Asian m...

Rhizomys sumatrensis

Rhizomys sumatrensis

Rhizomys sumatrensis,Indomalayan Bamboo Rat,Red-cheeked bamboo rat, Red bamboo rat

Rodents LC

Features:It is the largest species in the bamboo rat family.

The bamboo rat belongs to the subfamily Rhizomyinae, and the species is native to Malacca, Malaysia. It was recorded in China very early. The species-level classification status is stable, and there are 6 synonyms. There is some controversy as to whether these synonyms are independent species or sub...

Rhizomys sinensis Gray

Rhizomys sinensis Gray

Rhizomys sinensis Gray, bamboo rat, bamboo pig, bamboo civet, bamboo civet, bamboo weasel, reed rat, reed rat

Rodents LC

Features:It has a mole-like body, a stout appearance, similar to a zorrat, and dense, soft, brown-gray fur.

Like the silver-star bamboo rat, the Chinese bamboo rat is also a member of the subfamily Rhizomyinae. It lives underground for life and feeds on bamboo whips and bamboo shoots. It is distributed in Sichuan, Shaanxi and Gansu, and is co-existing with giant pandas. When the population is large, it wi...

Rhizomys pruinosus

Rhizomys pruinosus

Rhizomys pruinosus,Rhizomys latouchei, white bamboo rat, rough-haired bamboo rat, bamboo rat, Tulun

Rodents LC

Features:The body is stout and cylindrical, with rough fur and many long, white-tipped guard hairs scattered around, sticking out of the fur layer and shiny.

Silver-star bamboo rat belongs to the subfamily Rhizomyinae. In terms of classification, there is no dispute about the species-level classification unit, but the subspecies are more confusing. There are 3 subspecies in China, and whether they are established needs further research. They live undergr...

badius

badius

badius,Muscicapus, bamboo rat, winter rat, muscicapus, hog rat, bamboo civet, etc.

Rodents LC

Features:The eyes and ears are small, the limbs are short, and the claws are long and hard.

The bamboo rat belongs to the subfamily Rhizomyinae. There is only one species of the genus Rhizomyinae in the world. There is no dispute in its classification. Its distribution area in my country is narrow, its number is small, its specimens are very few, and its research is not in-depth. It lives...

Typhlomys macrourus Zheng

Typhlomys macrourus Zheng

Typhlomys macrourus Zheng,1993

Rodents LC

Features:The back of the body is dark gray, the tail is like a pig's tail, and there is a patch of white hair at the back.

The giant pig-tailed rat belongs to the Platacanthomyidae family, a very unique and ancient family. There are only 2 genera and 6 species, 4 of which are in China. The 4 species in China originally only had one pig-tailed rat (<Typhlomys cinereus>), the type locality is Fujian, of which there...

Sicista tianschanica

Sicista tianschanica

Sicista tianschanica,Sicista concolor,Rat

Rodents LC

Features:The body shape is similar to that of a house mouse, with a very long tail, about 1.5 times the body length. The tail is covered with short hair and does not form a hair bundle at the end.

Tianshan scissorium belongs to the subfamily Sicistinae, with only one genus - sicissorium (<Sicista>), with a total of 13 species, 4 of which are in China. This species is a rare species, with very few specimens and a very low rate of capture in the wild. It is distributed in mountain grassla...

Eozapus setchuanus

Eozapus setchuanus

Eozapus setchuanus,,Forest jerboa, forest jerboa, forest jerboa

Rodents LC

Features:It has a long tail, small eyes, long ears, and a wide longitudinal dark brown-yellow band on the central part of the back of the body.

The Sichuan forest jerboa belongs to the subfamily Zapodidae, which has only one species: the Sichuan forest jerboa. This species has 2 subspecies, the named subspecies was found in Kangding, Sichuan, with a "Y" shaped dark brown stripe in the middle of the abdomen; the Gansu subspecies wa...

Euchoreutes naso

Euchoreutes naso

Euchoreutes naso,Long-eared Jerboa,

Rodents LC

Features:It is small in size, with large and long ears; its tail is nearly twice as long as its body, and there is a spike of long hair at the end of its tail, which is black at the base and white at the tip.

The long-eared jerboa belongs to the subfamily Euchoreutinae, a single genus and a single species. There is no dispute about its taxonomic status, with 3 subspecies, 2 of which are in China. It inhabits deserts and sandy desert steppes. It is widely distributed, with a large population in sparse pop...

Dipus sagitta

Dipus sagitta

Dipus sagitta,Northern Three-toed Jerboa,Hairy-footed jerboa, gerbil, jumping rabbit, Yelaben (Mongolian)

Rodents LC

Features:It is of medium size, with a big head, big eyes, short ears, brown-gray fur on the back and pure white fur on the belly.

The three-toed jerboa belongs to the subfamily Dipodinae. This species is widely distributed in China, adapted to deserts, arid and semi-desert areas, with a large population, and is a common jerboa in my country.The three-toed jerboa is a sand-loving species. Although its habitat is diverse in term...

Salpingotus kozlovi

Salpingotus kozlovi

Salpingotus kozlovi,

Rodents LC

Features:It has a small body and a slender tail that is about twice its body length. The tail hair is sparse, the tail scales are visible, and the hair at the end of the tail is particularly long.

The three-toed cardiocraniinae belongs to the subfamily Cardiocraniinae. Although this species is widely distributed, its number is rare. There are very few specimens in the country. There is no dispute in classification, and there are 2 subspecies. There is very little information on ecology, and r...

Salpingotus crassicauda Vinogradov

Salpingotus crassicauda Vinogradov

Salpingotus crassicauda Vinogradov,Fat-tailed jerboa

Rodents LC

Features:Its body shape is similar to that of the three-toed heart-skulled jerboa, but its tail is shorter than that of the three-toed heart-skulled jerboa, its hind limbs are longer than its forelimbs, its hind feet have three toes, and there are brush-like pads of long hair under its feet.

The fat-tailed cardiocraniinae belongs to the subfamily Cardiocraniinae. There are 6 species in the genus Cardiocraniinae, 2 of which are in China. They are widely distributed, but very few in number. Their habitats include Haloxylon ammodendron deserts and abandoned farmland. The ecological researc...

Little gopher

Little gopher

Little gopher, hamsters, gophers

Rodents LC

Features:Smaller

The ground squirrel belongs to the Allactaginae subfamily. There are 3 species in the world, and only 1 in China. The number is relatively rare. It is a desert and semi-desert steppe species. The species status of this species is undisputed, and there are many subspecies. It is still unclear which s...

Allactaga elater

Allactaga elater

Allactaga elater,Jerboa, jumping rabbit, donkey jump, hard jump

Rodents LC

Features:Small in size and good at jumping

The small five-toed jerboa belongs to the subfamily Allactaginae. Jerboas are distributed in deserts and arid areas in North Africa, Arabia and northern Asia. They are one of the few mammals in this extreme environment. The species-level classification status of the small five-toed jerboa is stable...

Allactaga sibirica

Allactaga sibirica

Allactaga sibirica,Mongolian five-toed Jerboa,Five-toed jumping rabbit, jumping rabbit, jumping mouse

Rodents LC

Features:It is the largest species in the jerboa family, with a round head, big eyes, and big ears that can be folded forward to reach the tip of the nose. Its back is gray and its abdomen is pure white.

Five-toed jerboas belong to the Allactaginae subfamily. The species-level classification of five-toed jerboas is stable, and the subspecies differentiation is complex. There are more than 10 species, including 5 in my country, including the current Mongolian five-toed jerboas. But whether they are a...

Castor

Castor

Castor,Beaver, nutria

Rodents LC

Features:The body is obese, with no obvious difference between males and females. The head is short and blunt, the eyes are small, the neck is short, the limbs are short and wide, the forelimbs are short, and the tail is large and flat.

There are only two species of beavers in the world. The other is the American beaver, which is distributed in Canada and Alaska, USA. Beavers are highly adapted to aquatic life and can move underwater for a long time. They have the habit of building dams with branches and trunks and nesting next to...