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Birds are amazing creatures. To most of them, nature has bestowed the ability to use all three elements — air, earth, and water. This ability is due to the characteristics of the structure of the skeleton and muscles of birds, the presence of feather coating.
How does the skeleton of birds differ from the skeletons of other living beings, what are its features?
Birds were the first warm-blooded animals on Earth. This species originated from reptiles; today there are 40 detachments in it, which, in turn, consist of more than 200 families.
The peculiarity in the structure of the skeleton of birds is that it is clearly expressed fitness to fly. It consists of thin, flat and spongy bones. Cavities in them are filled with either air or bone marrow, depending on what functions they perform.
During the archaeological excavations, scientists find the skeletons of representatives of this class of animals, which are perfectly preserved, and explain their strength and resistance to external destroyers by their very structure.
The skeleton of any bird is divided into several so-called belts, each of which performs certain functions and carries a certain load. Due to the fact that the load is distributed correctly, the birds are able to fly, and not just soar on the air flow. Many of them can fly against the wind, and quite strong.
In addition, the skeleton is responsible for the safety of the individual – its cervical section is extremely mobile, the head of most birds can instantly turn immediately by 180˚. This helps not only to track the space around and notice the danger in time, but also to hunt productively.
The birds take their origin in the branch of archosaurs, which today no longer exists, that is, they remain its sole representatives. Archosaurs were an intermediary between reptiles and birds. Shorter forelimbs and elongated hind limbs were characteristic of their skeleton, as in the modern representatives of the bird class. The main and only difference – the Archosaur still had a long tail. The forelimbs, analogs of the wings of birds, the archosaur, according to scientists, used to cling to tree branches when moving. This animal could not fly.
Not all stages of the evolution of birds, scientists have been able to track. There are hypotheses that other classes of animals originate in the same branch. This is confirmed by the facts – in some of the species, the skeleton structure is similar to the skeleton structure of birds, there are similar “knots” in the muscle tissues, undeveloped adaptations for flight and soaring. A striking example of this is the chameleon and other subspecies of lizards.
The evolution of birds is reflected even in the folklore of some ethnic groups. The transitional stage is represented by dragons, Slavic snake-gorynych and other characters. It is interesting that many scientific hypotheses of the evolution of birds and their skeleton confirm the fabulous scenarios.
The skeleton of birds is different from the skeletons of other living creatures and external and internal signs. External differences – the shape of the body and skeleton, the location of the sockets on the skull, the absence of the ear entrance (shell), increased finger tenacity on the lower limbs, wings.
The bird's skeleton consists of several belts:
- skull and neck belt
- front limb girdle,
- pelvic girdle.
The skull of modern birds is similar to the skull of their ancient relatives reptiles. It consists of the occipital part, the upper mandible, the lower mandible and the hyoid apparatus. The occipital part is formed by four bones – the main, two lateral and upper. The articulation of the skull with the spine provides the occipital condyle, which is located under the occipital foramen. The roof and sides of the brain box are closed with paired bones – the frontal, scaly, parietal and wedge-shaped lateral. The bottom of the skull is formed by the integumentary wedge-shaped bone.
The beak is considered to be a complex part of the skull of birds. It is formed by a multitude of small bones – the crest and nasal bones, the paired cheekbones and the zygomatic square, the lower arch, the anterior ear bones, the articular and dental parts, the sublingual elongated body.
The belt of the fore limbs of the bird's skeleton is a complex structure formed by the shoulder blade, the clavicle, the coracoid. The peculiarity of this section of the skeleton of birds, which allows to fly, is that the humerus is very large and powerful. This factor ensures the stability of the wing with loads characteristic of flight.
The pelvic girdle of the skeleton of the bird forms accrete sciatic, iliac and pubic bones. Hind limbs, underdeveloped in terms of size, but strong, consist of tubular bones. In the structure of the paws of birds there is a so-called bobbin, which is an additional lever that significantly increases the step. In most species of birds, the number of toes on their paws is 4, but in some subspecies, ornithologists note a reduction when their number changes under the influence of external factors. Vivid examples of ostriches – in some species there are 3 toes on paws, some of them have only 2.
Another unique feature of the skeletal structure of birds is the practically fused vertebrae at its base. The most mobile part of the spine of the bird is the cervical. The skull is able to turn instantly by 180˚. Sedentary thoracic vertebrae are connected to the sacral region, which is absolutely immobile and is responsible for the ability of the bird to walk. It is followed by the pigostil – the caudal region of the spine, which in the course of evolutionary changes turned into a single coccygeal bone.
The bird is an amazing creation of nature, during the evolution of which changes have taken place not only in the structure of the skeleton, but also in the structure of the musculature and the principles of its connection with the bone base.
The most developed muscle group in birds is the pectoral region. Muscle tissues tightly attached to the bone-based individuals due to the so-called keel, bone growth in the sternum. The pectoral muscles in some species make up 1/5 of the total body mass. They are responsible for the ability to lower and raise the wings, that is, for the ability to fly.
The second place in terms of development and degree of attachment on the skeleton is the muscles of the hind limbs of the bird. This area of the muscular system is characterized by the presence of strong, but movable tendons, with the help of which individuals are fixed on branches, wires and can be held on them for a long time. The grasping function is one of the most important functions of the muscular system of the lower limbs of birds. In some species of this class of animals, the muscles of the paws (legs) are better developed than the muscles of the fore limbs, which are responsible for flight. The strength of such species – legs, and they, as a rule, do not fly. The most famous representative of the group is the ostrich.
For the ability to fly is responsible not only the skeleton with a special structure and the muscles of the bird, but also the pen system. It is formed by downy and contour feathers. Downy are responsible for heat transfer, and contour ones are responsible for movement and protection.
Birds fly with contour feathers. Most of them are located on the wings, they are on the tail of individuals. Tail contour feathers perform the role of a kind of steering, directing when hovering.
The structure of the flight contour feathers of birds is no less complex than the structure of their skeleton. They are formed by horn beards of the first and second row. The mount between them is carried out with hooks, which can only be viewed under a microscope. It is surprising how durable these mounts are.
Birds are one of the most amazing creatures. With serious evolutionary changes, they retained most of the features of their ancestor relatives.
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