• WordNet 3.6
    • n Rodentia small gnawing animals: porcupines; rats; mice; squirrels; marmots; beavers; gophers; voles; hamsters; guinea pigs; agoutis
    • ***
Webster's Revised Unabridged Dictionary
    • n. pl Rodentia (Zoöl) An order of mammals having two (rarely four) large incisor teeth in each jaw, distant from the molar teeth. The rats, squirrels, rabbits, marmots, and beavers belong to this order.☞ The incisor teeth are long, curved, and strongly enameled on the outside, so as to keep a cutting edge. They have a persistent pulp and grow continuously.
    • ***
Century Dictionary and Cyclopedia
    • rodentia An order of ineducabilian placental diphyodont Mammalia; the gnawers. The brain has a relatively small cerebrum, leaving much of the cerebellum and olfactory lobes exposed, and the corpus callosum has no well-defined rostrum in front. The placentation is discoidal-deciduate. The limbs are ambulatorial, variously modified for running, leaping, climbing, or swimming. The condyle of the lower jaw has its long axis longitudinal, and is not confined in a special socket, but glides back and forth, so that the lower jaw can be put forward and backward as well as moved up and down. The molar teeth are typically ridged on their crowns in various patterns; they are nearly always 3 in nnmber above and below on each side. The premolars are small or few, often none. There are no canines. The incisors are large, strong, heavily enameled on their front surface, scalpriform or beveled to a sharp edge, and grow continually from persistently open pulps; their roots traverse much or nearly all of the bones of either jaw, in the arc of a circle. The typical number of incisors is 2 above and below, or one pair of upper and under front teeth; exceptionally, as in the rabbit tribe, there are small supplementary upper incisors, crowded together and concealed behind the functional pair. In some groups, as Arvicolinæ, the molar teeth are perennial, like the incisors. There being no canines, and the premolars being few and small, if any, there is a great gap between the front and the back teeth. The typical number of teeth is 16, which obtains with few exceptions throughout the murine series of rodents; in one genus there are only 12. In the hystricine series there are normally 20 teeth, in one genus 16. In the sciurine series the teeth are always either 20 or 22; in the leporine series there are 26 or 28. This order is by far the largest one among mammals, and of world-wide distribution; its numerous members are adapted to every kind of life. They are mostly of small size, a rabbit being far above the average; the beaver, porcupine, or coypou is a very large rodent, and the capibara is a giant. The order is divisible into 3 suborders: Hebetidentata, enormal or blunt-toothed rodents, exceptional in having 4 lower incisors, and extinct; Duplicidentata, subnormal or double-toothed rodents, with 4 upper incisors: these are the hares, rabbits, and pikas; and Simplicidentata, normal or simple-toothed rodents, with only 2 incisors above and below. The last fall in 3 series: Hystricomorpha, the hystricine series, including the porcupines and very numerous related forms, chiefly South American, as the capibara, coypou, cavies, viscachas, chinchillas, octodonts, etc. (see cuts nnder capibara, coypou, rabbit-squirrel, porcupine, and Plagiodon); Myomorpha, the murine series, including rats and mice of all kinds (see cuts under mouse, Muridæ, and rice-field); and Sciuromorpha, the sciurine series, or the squirrels, spermophiles, marmots, beaver, etc. (see cuts under Arctomys, beaver, and prairie-dog). In addition, the duplicident rodents are Lagomorpha, the leporine series, the same as the suborder Duplicidentata, (See cut under Lagomys.) Many fossils of all these groups are known. There are 20 or 21 families of living rodents, and 100 genera. The order corresponds to the Linnean Glires, and is still often called by that name. Also called Rosores. See cuts under castor, Leporidæ, and scalpriform.
    • ***
Chambers's Twentieth Century Dictionary
    • Rodentia an order of mammals including squirrels, beavers, rats, rabbits, &c
    • ***


Webster's Revised Unabridged Dictionary
NL. See Rodent (a.)
Chambers's Twentieth Century Dictionary
L. rodĕre, to gnaw.


In literature:

The order Rodentia is here very numerous in species: of mice alone I obtained no less than eight kinds.
"A Naturalist's Voyage Round the World" by Charles Darwin
The field mouse and rabbits are rodentia, the deer ungulata, the kangaroos marsupialia.
"Concerning Animals and Other Matters" by E.H. Aitken, (AKA Edward Hamilton)
Apparently singular as is the elephant in its anatomy, it bears traces of affinity to both Rodentia and Ungulata.
"Natural History of the Mammalia of India and Ceylon" by Robert A. Sterndale
Squirrels are some of the most beautiful of the Rodentia, and chiefly live in trees.
"Anecdotes of the Habits and Instinct of Animals" by R. Lee
The fossil toxodon resembled the Rodentia in its dentition, and, at the same time, was nearly related to the elephant.
"The Western World" by W.H.G. Kingston
Thirdly, the relation of the living Edentata and Rodentia to the extinct species.
"Life of Charles Darwin" by G. T. (George Thomas) Bettany
They are perfectly harmless, and live on small animals, chiefly the rodentia.
"The World and Its People: Book VII" by Anna B. Badlam
The finest and closest wools are possessed by the amphibious Carnivora and Rodentia, viz.
"Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 3" by Various
Nagetiere (Mammalia, Rodentia) aus El Salvador.
"Speciation and Evolution of the Pygmy Mice, Genus Baiomys" by Robert L. Packard
Canine teeth are present in the majority of mammals, but are absent without a single exception from the jaws of the Rodentia.
"The Cambridge Natural History, Vol X., Mammalia" by Frank Evers Beddard

In news:

Chordata Class: Mammalia Order: Rodentia Family: Sciuridae Genus: Cynomys.