Reptiles

In most modern reptiles, both features of simpler amphibians in structure and features of higher vertebrates are conditionally observed.

Veil

The outer skin of modern reptiles as a result of thickening and keratinization forms scales or scutes. In lizards, horny scales overlap, resembling shingles. In turtles, fused shields form a solid solid shell . Horn cover is changed by full or partial molting , which in many species occurs several times a year.

Along with this, ancient reptiles could also be covered with peculiar feathers (which are a specialized form of scales in structure) or fluff-like formations (progressive archosaurs ).

Dense and dry skin contains odorous glands . Mucous glands are absent - the skin of reptiles is dry, smooth scales give it a characteristic shine.

In the outer part of the inner layer of the skin there are often special cells - chromatophores . Pigments are secreted in these cells: melanins and carotenoids . Also able to reflect light guanine in chromatophores. Thanks to chromatophores, some reptiles are able to change the color of their bodies in a relatively short time. Chameleons are the most famous representatives with a similar property.

Skeleton

In the axial skeleton of reptiles, the division into departments is more noticeable than in amphibians . Five sections of the spine are clearly distinguishable: cervical ( lat. Pars cervicalis ), trunk (lumbar-thoracic, pars thoracolumbalis ), lumbar, sacral ( pars sacralis ) and caudal ( pars caudalis ).

Typical for reptiles is the following structure of the axial skeleton. The total number of vertebrae varies in different species (50–80, in snakes it rises to 140–435). From the vertebrae of the cervical region (from 7 to 10), two anterior ones ( atlas and epistrophy ) form a joint that allows the head not only to move in a vertical plane relative to the first cervical vertebra, but also to turn. In the trunk from 16 to 25 vertebrae, each with a pair of ribs. The first few pairs of ribs attach to the sternum, forming the rib cage (absent in snakes). In the sacral section there are only two vertebrae, to the wide transverse processes of which the pelvis is attached. The tail section consists of several tens (15-40) gradually decreasing in size of the vertebrae. The last caudal vertebrae are small rod-shaped bones.

In some reptile groups, the axial skeleton is different. In snakes, the spine is clearly divided only into the trunk and tail sections, the sternum is absent. In turtles, the vertebrae of the trunk join together with the dorsal shield of the carapace, as a result of which they are motionless.

The skull of reptiles is much more ossified than that of amphibians. Only a small amount of cartilage is contained in the olfactory capsule and auditory region. The axial and visceral parts of the skull are embryo-formed separately, but in adults they grow together into a single entity. The composition of the skull includes both cartilage (replacement, or primary), and numerous skin (integumentary, or secondary) bones .

The belt of the forelimbs is similar to the belt of amphibians, differing only in the stronger development of ossification. A pair of forelimbs of reptiles consists of a shoulder , forearm and hand . A pair of hind limbs - from the thigh , lower leg and foot . Claws are located on the phalanges of the limbs.

Muscular system

The muscular system of reptiles is represented by chewing, cervical muscles , muscles of the abdominal press , as well as muscles of flexors and extensors. There are intercostal muscles characteristic of amniotes , which play an important role in the act of breathing . The subcutaneous muscles allows you to change the position of the horny scales.

The energy supply of the arbitrary muscles of modern reptiles occurs mainly due to anaerobic decomposition of glucose - about 50 ... 75% of the muscle fibers in their muscles are adapted to work in anaerobic conditions (without oxygen). Such metabolism allows them to travel short distances as fast as warm-blooded animals, and provides even greater muscle contraction power, and the intensity of the reaction in many groups is weakly dependent on body temperature. However, after 1-2 minutes of intensive work of the muscles in anaerobic mode, lactic acid accumulates in it, which leads to the onset of a kind of muscle fatigue and a change in blood pH. As a result, after just a few quick runs, the reptile becomes practically incapable of active action for a period of several minutes to several hours, which is required for the breakdown of the lactic acid accumulated in the muscles. ^[7] Larger animals are able to tolerate the accumulation of lactic acid in the muscles for longer and thus are actually more resilient. Crocodiles have outstanding anaerobic abilities and are able to withstand a drop in blood pH to 6.42 or lower ^[8] . Some modern reptiles, in particular, monitor lizards and a leatherback turtle , however, are an exception to this rule: during activity, their metabolic rate can reach more than half of that of warm-blooded animals of comparable weight, and they rely heavily on aerobic metabolism. almost without problems with the accumulation of lactic acid. ^[9]

Among extinct ancient reptiles, highly mobile forms are known (such as archosaurs: terrestrial crocodilomorphs , dinosaurs and pterosaurs , as well as mosasaurs , ichthyosaurs and sauroperterigias ), whose body structure and expected lifestyle testify to the ability to maintain prolonged muscle activity without fatigue, which corresponds to a more intense, than modern reptiles, metabolism, and muscle work mainly by the aerobic mechanism, requiring an intensive supply of oxygen. This, in turn, should have been accompanied by a completely different physiology of the body (complete separation of the ventricles of the heart, increased breathing efficiency due to the separation of the airways from the oral cavity, the appearance of effective thermoregulation mechanisms, and so on). These changes are partly traceable to paleontological material in the reptile line leading to the birds. At present, the existence of warm-bloodedness ( endothermic thermoregulation system) has been reliably shown in at least some groups of dinosaurs and ancestors of modern crocodiles, as well as plesiosaurs, mosasaurs and ichthyosaurs. ^{[10] [7] [11]}

Nervous system

As with most chordates , the central nervous system of reptiles is represented by the brain (from 5 divisions) and the spinal cord.

The brain is located inside the skull. A number of important features distinguishes the brain of reptiles from the brain of amphibians. Often they talk about the so-called zavropsid type of the brain, which is also characteristic of birds, in contrast to the ichthyopsid type in fish and amphibians.

Five sections of the reptile brain are distinguished.

• The forebrain consists of two large hemispheres, from which the olfactory lobes depart. The surface of the cerebral hemispheres is absolutely smooth. In the cerebral vault of the hemispheres, the primary arch is distinguished - the archipallium , which occupies most of the roof of the hemispheres, and the rudiments of neopallium . The bottom of the forebrain consists mainly of striatum .
• The diencephalon is located between the forebrain and midbrain. In its upper part is the pineal gland , and on the lower side is the pituitary gland . Most lizards and hatteria (as well as many extinct forms) develop a parietal eye near the pineal gland, and crocodiles lose both of these organs. The bottom of the diencephalon is occupied by the optic nerves and their cross ( chiasm ).
• The midbrain is represented by two large front hills - visual lobes, as well as small rear hills. The visual cortex is more developed than that of amphibians.
• The cerebellum covers the front of the medulla oblongata. It is larger compared to the cerebellum of amphibians .
• The medulla oblongata forms a bend in the vertical plane, which is characteristic of all amniotes.

12 pairs of cranial nerves depart from the brain. In the spinal cord, the division into white and gray matter is more distinct than in amphibians. Segmental spinal nerves depart from the spinal cord, forming a typical brachial and pelvic plexus. The autonomic nervous system ( sympathetic and parasympathetic ) in the form of a chain of paired nerve ganglia is clearly expressed.

Sense organs

Reptiles have six major sensory organs , of which vision is critical.

• The organ of vision - the eyes , are more complex than amphibians : in the sclera there is a ring of thin bony plates; an outgrowth extends from the posterior wall of the eyeball - a scallop protruding into the vitreous body ; the striated muscles are developed in the ciliary body, which allows not only to move the lens , but also to change its shape, thus providing focusing during accommodation . The organs of vision have adaptations to work in the air. The lacrimal glands protect the eyes from drying out. The outer eyelids and the blinking membrane have a protective function. In snakes and some lizards, the eyelids grow together, forming a transparent shell. The retina can contain both rods and cones . Nocturnal species have no cones. In most daytime species, the range of color vision is shifted to the yellow-orange part of the spectrum. The pupil shape is most often round or in the form of a vertical slit (like a cat's), a horizontal slit-like pupil, which is very common in amphibians, is very rare among reptiles, for example, braided snakes . The parietal eye , preserved in some species, is important for orienting in space and synchronizing the circadian rhythms of the body with the cycle of day and night, although much of its functions are still unclear ^{[12] [13]} .
• The organ of smell is represented by the internal nostrils - the choanas and the vomeronasal organ . Compared to the structure of amphibians, choans are located closer to the pharynx, which makes it possible to breathe freely while the food is in the mouth. The sense of smell is better developed than that of amphibians, allowing many lizards to find food beneath the surface of the sand at a depth of 6-8 cm.
• The organ of taste is the taste bulbs, located mainly in the throat .
• The organ of thermal sensitivity is located on the facial fossa between the eye and nose on each side of the head. Especially developed in snakes. In pit snakes, radars can even determine the direction of the source of thermal radiation.
• The organ of hearing is close to the organ of hearing of frogs, it contains the inner and middle ear , equipped with an eardrum , an auditory ossicle - a stirrup and an Eustachian tube. The role of hearing in the life of reptiles is relatively small, hearing is especially weak in snakes that do not have a tympanic membrane and perceiving vibrations propagating on the ground or in water. Reptiles perceive sounds in the range of 20–6000 Hz , although most hear well only in the range of 60–200 Hz (for crocodiles, 100–3000 Hz).
• Touch is pronounced, especially in turtles, which can even feel a light touch on the shell.

Respiratory system

Reptiles are characterized by breathing of the suction type by expanding and narrowing the chest with the help of intercostal and abdominal muscles. Air entering the larynx enters the trachea - a long breathing tube that is divided into bronchi leading to the lungs at the end. Like amphibians, reptile lungs have a bag-like structure, although their internal structure is much more complicated. The inner walls of the lung bags have a folded cellular structure, which significantly increases the respiratory surface.

Since the body is covered with scales, reptiles have no skin breathing (the exception is soft-bodied turtles and sea ​​snakes ), and the lungs are the only respiratory organ.

Circulatory system

Like amphibians, most reptiles have a three-chamber heart , consisting of a ventricle and two atria . The ventricle is divided by an incomplete septum into two halves: the upper and lower, and can be conditionally divided into three departments. However, as you know, the three-chamber heart of reptiles has developed independently of that of amphibians, and differs in terms of structure (and sometimes functionality) in different modern groups ^{[14] [15]} .

With this design of the heart, a gradient (difference) in the amount of blood oxygen is established in the slit-like space around the incomplete septum of the ventricle. After atrial contraction, arterial blood from the left atrium appears in the upper half of the ventricle and displaces the venous blood that has poured from the right side of the ventricle into the lower half. In the right part of the ventricle is mixed blood. When the ventricle contracts, each portion of blood rushes to the nearest opening: arterial blood from the upper half to the right aortic arch, venous blood from the lower half to the pulmonary artery, and mixed blood from the right side of the ventricle to the left aortic arch. Since it is the right aortic arch that carries blood to the brain, the brain receives the most oxygen-rich blood.

Being archosaurs, crocodiles have a four-chamber heart ^[11] . The septum completely divides the ventricle into two halves: the right - venous and left - arterial, thus isolating a full four-chamber heart, like in mammals and birds. Only after the formation of complete partitions in crocodiles does the Pannica hole form during embryogenesis (see biogenetic law ), which allows for controlled mixing of arterial and venous blood, which is associated with a secondary decrease in metabolic rate in this group of animals.

In contrast to the common arterial trunk of amphibians, in reptiles there are three independent vessels: the pulmonary artery and the right and left aortic arches. Each aortic arch bends back around the esophagus, and converging with each other, they connect into an unpaired spinal aorta. The spinal aorta stretches back, sending along the path of the artery to all organs. From the right aortic arch, extending from the left arterial ventricle, the right and left carotid arteries branch out with a common trunk, and both subclavian arteries, carrying blood to the forelimbs, depart from the right arch.

A complete separation into two independent circles of blood circulation in reptiles does not occur, since venous and arterial blood mix in the spinal aorta.

Like fish and amphibians, the vast majority of modern reptiles are cold-blooded animals . Despite this, many reptiles can adjust the temperature by moving from the shadows to the sun and back, or changing color, becoming darker to keep warm, or lighter to cool.
More recently, facus lizards have been found to have optional endothermia - the ability to increase body temperature during the breeding season due to endothermic chemical reactions ^[16] . Lizards in the midst of food activity can also increase body temperature due to internal processes ^[17] . The skin turtle, in turn, has an insulating fat layer and due to intense muscle activity it can be about 18 degrees warmer than the surrounding water ^[18] .

Digestive system

Due to the variety of food available for nutrition, the digestive tract in reptiles is much more differentiated than in amphibians .

The digestive system begins with a mouth opening limited by jaws with usually conical, identical, firmly growing teeth (a homodontic system, although some extinct forms had a heterodontic). The tongue is free, muscular in front, mobile, by the end it is thinning and bifurcating. The oral cavity is delimited from the pharynx by a developing secondary bone palate in lizards and turtles, a fully developed bone palate in crocodiles, but there is no secondary bone palate in snakes and monitor lizards. Multicellular salivary glands contain digestive enzymes. The pharynx passes into the narrow esophagus , then into the muscular stomach and intestines . The stomach has thick muscle walls. On the border between the small and large intestine is the cecum , which amphibians do not have. The large reptile liver has a gall bladder . The pancreas in the form of a long dense body lies in the loop of the duodenum . The intestines end with cesspool .

Excretory system

The excretory system of reptiles is represented by the kidneys , ureters and urinary bladder .

The buds of reptiles are significantly different from the kidneys of fish and amphibians, which have to solve the problem of getting rid of a constant excess of water in the body. Instead of the trunk kidneys of amphibians ( mesonephros ), the kidneys of reptiles ( metanephros ) are located in the pelvic region from the ventral side of the cloaca and along its sides. The kidneys connect to the cesspool through the ureters.

Thin-walled stalked bladder connects to the cesspool thin neck on its abdominal side. In some reptiles, the bladder is underdeveloped (crocodiles, snakes, some lizards).

A new excretory organ, the pelvic kidney, also appears.

In terrestrial reptiles, the end product of nitrogen metabolism is uric acid .

The reproductive system

Reptiles - dioecious animals, bisexual reproduction.

The reproductive system of males consists of a pair of testes that are located on the sides of the lumbar spine. From each testis departs the seed canal , which flows into the wolf canal . With the appearance of the pelvic kidney in reptiles, the canal in males appears only as a vas deferens and is completely absent in females. The Wolf channel opens into the cesspool, forming a seminal vesicle .

The female reproductive system is represented by the ovaries , which are suspended on the mesentery to the dorsal side of the body cavity on the sides of the spine. Oviducts ( Müller channels ) are also suspended on the mesentery. In the front of the body cavity, the oviducts open with slit-like openings - funnels. The lower end of the oviduct opens into the lower part of the cloaca on its dorsal side.

Development

Fertilization is internal. The development of the embryo occurs in an egg with a leathery or calcareous membrane; along with this, an egg- bearing birth and (less often) a true live birth are found . Reptiles have direct postembryonic development . Many representatives are characterized by care for offspring, in particular, female crocodiles carry offspring from the place of masonry to ponds in the oral cavity, although in some cases they can eat a cub.

Nutrition

Most reptiles belong to carnivores (including carnivores and eating, carnivores , a number of lizards and most snakes are true predators among modern reptiles). For some (for example, agamas , iguanas ) mixed nutrition is characteristic. Sometimes there are almost exclusively herbivorous reptiles ( land turtles ).

Movement

Primitive groups of ancient amniotes (including the first reptiles) originally moved on four widely spaced extremities, which, when locomotion, moved apart medially and were not able to constantly support the body above the ground, hence the “creep”, dragging the abdomen along the ground, which gave the Russian name this entire group, which corresponded to their characteristic low level of metabolic rate and a relatively sedentary lifestyle associated with the alternation of short flashes actively sti and long rest lying on his stomach. Modern reptiles basically preserve the similar, evolutionarily basal nature of locomotion, with some exception only crocodiles, in which limbs can run almost under the torso when running. Moreover, in some extinct groups of the modern crocodile detachment, which led an exclusively land way of life, this position of the limbs was habitual, that is, it was maintained most of the time - in Australia such land crocodiles (for example, Quincan ) lived 40 thousand years ago, that is, at the same time with a man of a modern kind.

There are specialized crawling forms - snakes , legless lizards . Most reptiles swim well due to the "fish-like" bending of the body in the transverse plane. In some groups, adaptation to the aquatic environment reached a higher degree, and during the evolution process they developed various types of locomotion. So, ichthyosaurs , mosasaurs and, to a lesser extent, crocodiles preserved the nature of swimming due to transverse bends of the body. On the other hand, sea turtles and extinct plesiosaurs developed a new mechanism of movement in water, due to sweeps of limbs that turned into flippers . Many of these groups have almost completely lost their ability to travel on land. Several reptile genera are capable of planning flights - for example, flying dragons (Draco agamas) and tree flying snakes from the genus Chrysopelea . Actively flying reptiles are known only from fossil remains (see Pterosaurs ).

In ancient times, the development of some advanced groups of reptiles went in different directions - their limbs began to move directly under the body, occupying a more habitually vertical (straightened) position, which corresponded to a more mobile way of life associated with fast running and active pursuit of prey.

In the ancestors of the archosaurs, the pubic and ischial bones began to lengthen, the front legs began to shorten, and the heavy long tail, which was almost immobilized due to the fusion of the pelvic bones, turned into a balancer, balancing the mass of the elongated body. The hind limbs began to move in the parasagittal plane when walking, the ankle joint was able to spring when walking, which contributed to a more economical expenditure of forces, and the support moved to the middle (third) finger. This allowed many groups of tecodonts to switch to optional, or even habitual, bipedality, like modern running birds, specializing in running on two legs.

These changes should have been accompanied by a significant increase in metabolic rate, since the constant maintenance of the body above the ground and long locomotor activity required much greater energy consumption compared to the "creep". However, it is difficult to trace such changes on paleontological material. It is reliably known, however, that the descendants of this group of reptiles - birds - have an intensive metabolism and an endothermic system of thermoregulation (warm-bloodedness).

The immediate descendants of the tecodonts - the early dinosaurs , both lizardotazovy and poultisase - were active predators, moving at least part of the time on the hind limbs, which contributed to their rapid progress, especially after the extinction of most synapsids at the turn of the Permian and Triassic period. In the Jurassic period, almost all the more or less large land animals (over a meter in length) were dinosaurs.

Gradually, part of the dinosaurs switches to plant foods, occupying vacant ecological niches. Most herbivorous species again returns to movement on four limbs, while the evolution of predators continues to follow the “two-legged” path (for example, in the tyrannosaurus and tarbosaurus, the forelimbs turned out to be practically reduced, and in maniraptors , on the contrary, they developed into a specialized grasping form). For 140 million years, until the end of the Cretaceous, the main terrestrial predatory vertebrates were bipedal dinosaurs, some of whose forms are indistinguishable from birds in most signs.

As you can see, historically, for reptiles, it was mainly active movement on two or four straightened limbs that was characteristic, it was these running forms that occupied a dominant position in this class (paraphyletic group) of animals for most of its history. Bipedal predatory forms occasionally arose in birds - for example, fororakosa . В настоящее время подобные формы среди рептилий не возникают, поскольку экологические ниши, связанные с активным преследованием добычи, ныне заняты млекопитающими, и организм современных рептилий требует значительной перестройки для их освоения. Некоторое исключение составляет насекомоядная плащеносная ящерица , и некоторые другие агамовые, способные к бегу на двух ногах (при сохранении расположения конечностей по бокам от туловища). Такая особенность позволяет им обходить ограничение Карриера (невозможность бежать на четырёх ногах и дышать одновременно) и активно преследовать добычу или спасаться от хищников. Ящерица шлемоносный василиск во время бипедальной локомоции способна также бегать по поверхности воды. Тегу и вараны также научились обходить ограничение Карриера, но за счет модификации дыхательной системы, а не подъёма на задние конечности.

Большинство рептилий не имеет настоящего голосового аппарата и производят лишь самые примитивные звуки вроде шипения или свиста. Крокодилы рычат, издают лающие и рокочущие звуки, детеныши квакают. Черепахи в некоторых случаях (испуг, брачный сезон, боль) могут издавать писк или стон. Представители гекконовых ящериц издают самые разные звуки — писк, визг, щебет, щелчки, крики ^[19] .

Значение пресмыкающихся для человека сравнительно невелико. Кожа крокодилов, крупных змей и ящериц применяется в кожевенной промышленности для изготовления чемоданов, ремней, обуви и т. п., однако эти предметы носят эксклюзивный характер, являясь предметом роскоши. Мясо и яйца многих черепах употребляются в пищу. Также могут употребляться в пищу некоторые ящерицы и змеи. Змеиный яд находит применение в медицине. Многие змеи полезны истреблением грызунов, а ящерицы — насекомых. Некоторые виды пресмыкающихся держат в качестве домашних животных . Аллигаторы, кайманы и некоторые крокодилы иногда разводятся на специальных фермах, для получения мяса, яиц и кожи.

Большую опасность для людей представляют ядовитые змеи, особенно в тропических странах. Многие крокодилы опасны для человека, наносят значительный ущерб животноводству. Пресноводные черепахи вредят рыбному промыслу. Крупные вараны, питоны и удавы так же могут быть опасны, будучи способными травмировать или даже убить человека.

Первые представители пресмыкающихся — котилозавры — известны со среднего карбона . К концу периода появляются зверообразные , которые в пермском периоде расселяются практически по всей суше, становясь одной из господствующих групп и составляя конкуренцию пресмыкающимся. В мезозойской эре наступает расцвет пресмыкающихся, среди представителей наблюдается наибольшее многообразие. Происходит освоение морских и речных водоёмов, а также воздушного пространства. В мезозое происходит формирование всех современных групп пресмыкающихся. Последняя группа — змеи — сформировалась в меловом периоде .

В конце мелового периода происходит резкое сокращение количества видов пресмыкающихся. Однозначно указать причины вымирания современная наука пока не может.

В 2011 году был расшифрован геном пресмыкающегося — ящерицы анолис каролинский ^[20] . Таким образом, это пресмыкающееся вошло в круг модельных объектов генетики.

В классификации пресмыкающихся много неясного, во многом потому, что большая их часть вымерла.

Класс Пресмыкающиеся (Reptilia)

• Подкласс Анапсиды (Anapsida)
  • † ? Отряд Котилозавры (Cotylosauria)
  • † Отряд Captorhinida
  • † Отряд Мезозавры (Mesosauria = Proganosauria)
  • † Отряд Проколофономорфы (Procolophonomorpha)
• Подкласс Диапсиды (Diapsida)
  • † Отряд Ареосцелидии ( Araeoscelidia )
  • Группа Эозухии (Eosuchia)
    • † Группа Avicephala
    • Группа Neodiapsida
      • † Отряд Юнгинии ( Younginiformes )
      • † ? Отряд Hupehsuchia
      • † ? Отряд Thalattosauriformes
      • † ? Надотряд Ихтиоптеригии ( Ichthyopterygia )
        • † Отряд Ихтиозавры (Ichthyosauria)
      • † Хористодеры ( Choristodera )
      • Инфракласс Лепидозавроморфы (Lepidosauromorpha)
        • † ? Надотряд Зауроптеригии (Sauropterygia)
          • † Отряд Eosauropterygia
          • † Отряд Нотозавры (Nothosauria)
          • † Отряд Плакодонты (Placodontia)
          • † Отряд Плезиозавры (Plesiosauria)
        • Надотряд Лепидозавры (Lepidosauria)
          • Отряд Клювоголовые (Rhynchocephalia)
          • Отряд Чешуйчатые (Squamata): ящерицы , змеи и двуходки
      • Инфракласс Архозавроморфы (Archosauromorpha)
        • † Отряд Проторозавры (Protorosauria)
        • † Отряд Prolacertiformes
        • † Отряд Ринхозавры (Rhynchosauria)
        • Отряд Черепахи (Testudines или Chelonia) ^[21]
        • Группа Архозавры (Archosauria)
          • Группа Круротарзы (Crurotarsi) или Псевдозухии (Pseudosuchia)
            • † Отряд Фитозавры (Phytosauria)
            • † Отряд Rauisuchia
            • † Отряд Этозавры (Aetosauria)
            • Надотряд Крокодиломорфы (Crocodylomorpha)
              • Отряд Крокодилы (Crocodilia) — единственные выжившие современные представители
          • † Группа Avemetatarsalia
            • † Клада Aphanosauria
            • † Группа Орнитодиры (Ornithodira)
              • † Отряд Птерозавры или летающие ящеры (Pterosauria)
              • † Группа Dinosauriformes
                • † Семейство Silesauridae
                • † Надотряд Динозавры (Dinosauria)
                  • † Отряд Ящеротазовые (Saurichia) — вероятно дали начало птицам
                  • † Отряд Птицетазовые (Ornithischia)

• Пресмыкающиеся, описанные в 2010 году
• Пресмыкающиеся, описанные в 2009 году

• Наумов Н. П., Карташев Н. Н. Часть 2. Пресмыкающиеся, птицы, млекопитающие // Зоология позвоночных. — М. : Высшая школа, 1979. — С. 272.
• Карташев Н. Н., Соколов В. Е., Шилов И. А. Практикум по зоологии позвоночных . — М. : Высшая школа, 1981.
• Биологический энциклопедический словарь под редакцией М. С. Гилярова и др., М., изд. Советская Энциклопедия, 1989.
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