Small and medium-sized mammals (the size of the mouse to a porcupine), is very different in body shape. Limbs five, less than four-and three-fingered, the last phalanx usually armed with claws. The coat is developed, often differentiated into hair and beard undercoat, guard hairs may be modified in the needle. Clavicle usually present. Small and tibia fused in their lower part, or free.
The front section of the skull is shorter than cerebral. Orbit without bone behind the arc open, highly inflated auditory bulla. Very mobile articulation of the lower jaw (the adaptation to chewing and chafing plant food). Developed chewing muscles. Greatly lengthened intestine developed cecum.
Teeth differentiated into incisors and indigenous. Canines not. Indigenous separated from incisors large gap, devoid of teeth — diastema. Large molars have no sharp prominent peaks. Chewing surface provided with their crests or blunt tubercles, and some representatives — flat. A well defined indigenous roots or roots are reduced. Incisors always without roots. These teeth are constantly growing and self-sharpening for nibbling.
Hemispheres of the brain are small, do not cover the cerebellum, usually with a smooth surface. Bicornuate uterus. Penile bone (os penis) present or absent.
Rodents — mostly land animals that are adapted to transfer rapidly changing conditions of existence, rapidly recovering strength. Ability to proliferate in a wide variety of conditions determines they have a rapid rate of evolution than in other units: rodents — a group that flourished in the present geological epoch. Adapt to different lifestyles are very diverse: from ground (mice, rats) to entirely underground (mole rats, zokor) and semi (some hamsters, voles) and the run (gerbil) and jump (jerboa, Strider) to Laza (squirrels, mice -baby), there are forms that are adapted to a gliding (flying squirrels).
Currently, rodents spread across the globe to the extreme terrestrial life.
The number of species of rodents in the USSR is about half of all mammal species of its fauna. In Kazakhstan, there are about 70 species of rodents, consisting of nine families: squirrel, letyazhih, selevinii, porcupines, dormice, tushkanchikovyh, after-pysheobraznyh, Cricetidae and mouse.
Of the 70 species known from Kazakhstan, four — endemic: battle-lychnaya dormouse (Seleuinia betpakdalensis), tolstohvosty jerboa (Pygerethmus platyurus), jerboa Zhitkova (P. zhitkovi), Vinogradov's Jerboa (P. vinogradovi).
Rodents have diversified economic value. Are a significant source of furs. Many species — pests of agriculture, carriers and holders of certain infections and infestations.
Key to the families of rodents, represented in Kazakhstan
1 (14). In the lower jaw to three indigenous ….. 2
2 (3). The molar teeth are small and very rudimentary. They barely protruding from the gums.
In the upper jaw, their is up to five. The upper incisors are very large relative to the deep groove on the front surface
Selevinii — Seleviniidae.
3 (2). Molars develop normally. In the upper jaw of a maximum of four
The upper incisors of normal size or no furrows or with weakly developed grooves. 4.
4 (5). Hind legs are very long, about three or four times longer than the front, adapted to jumping. Rear foot or with two lateral toes, do not reach their ends to the base of the three middle fingers, or with only three fingers. The skull is wide and short. Infraorbital holes are very big ….
Tushkanchikovye — Dipodidae.
5 (4). Hind limbs do not differ in length from the front or no more than two times higher than them. Hind foot with five toes always, and, at least, the outer toe always reaches its grounds kontsomdo three middle fingers. The skull is elongated. Infraorbital small holes .. 6.
6 (7). Molars 4 / s ….Tushkanchikovye — Dipodidae.
7 (6). Molars 3/3 .8.
8(9). No eyes (the skin is not cut for the eyes, eyeball minor
values, hidden under the skin). Occipital area of skull very large Shai, obliquely sloping from front to back
Slepysheobraznye — Spalacidae.
9 (8). The eyes are always visible from the outside. Occipital area of skull relatively
small and has a more or less vertical polozhenie.10.
10 (11). Forelimbs are armed with huge sickle claws.
11 (10). The claws on the front legs of normal size and have a crescent shape …. 12.
12 (13). Occlusal surface of the first and second upper molars pok-
ryta enamel tubercles, which are arranged in three longitudinal rows. Muridae — Muridae.
13 (12). Occlusal surface of the first and second upper molar teeth covered by enamel tubercles arranged in two longitudinal rows, or completely flat, formed by alternating or facing each other enamel loops
Cricetidae — Cricetidae.
14 (1). In the lower jaw more than three molars . . . 15.
15 (18). Molars bU. Supraorbital processes are well developed . 16.
16 (17). Between the front and rear is covered with fur warehouse
ka kozhiLetyagi — Pteromyidae.
17 (16). Between the front and rear folds of skin is not ..
Squirrel — Sciuridae.
18 (15). Molars 4, V Supraorbital processes are absent or are in the form
weak zachatkrv .. 19.
19 (21). The upper part of the body is covered with long needles. The length of the nasal bones
is about'' / "total length of the skull
.. Porcupines — Hystricidae.
20 (19). The upper part of the body is covered with hair. The length of the nasal bones less half
the total length of the skull 21.
21 (26). Body length of adult animals at least 50 see The tail is flattened on top
down, shovel-shaped, covered with large cheshuyamn.
Beavers — Castoridae.
22 (21). Body length of less than 25 adult animals see Tail neuploschenny, lishenkrupnyh flakes and covered with fur. Sony — Myoxidae.