Ostriches are special beautiful and "important" birds. Their appearance surprises with its large size, strong muscles on the legs, the ability to run fast and the imperfection of the wings that are not adapted for flying, even for short distances.
Where did such a big and beautiful bird have such a flaw? A distinctive feature of the ostrich is the modified structure of the sternum.which looks like a flat surface instead of the shape of the keel, as it usually should be in birds. In addition, the muscles in the sternum are underdeveloped, which makes it impossible for the ostrich to flap its wings.
Note also that the ostriches are heavyweights among their relatives. The bone system of these birds is special. There are no air cavities in all bones, except those in the femoral part of the body.therefore they are very heavy. All flying birds have light bones with a large number of air cavities.
Scientists have proven that the ancestors of modern ostriches flew, but modern birds have lost this ability due to the constant search for new ways of survival. Great weight prevented quickly take off, even with any danger. In addition, the territory was needed for a large run. Therefore, it is precisely to run fast in an ostrich that turned out much better than to fly away. Thus, they survived, they had offspring that refused to fly, but they did very well to run. As a result, the wings of these birds have ceased to carry out their original function, but with the help of strong and muscular legs, ostriches can now run at a speed of up to 70 km / hour. Since the wings are now in an underdeveloped form and there are only steering and fly feathers that act as decorations, modern ostriches now do not know how to fly.
Why the ostrich does not fly: reasons
In the animal world, wild ostriches are distinguished by enviable survival. Living in African shrouds, they constantly undergo attacks from hungry predators and escape from them, thanks to their ability to run fast. In an hour, these birds can reach speeds of up to 70 kilometers, which is not possible for every four-legged mammal. For comparison, the sprint athletes during running competitions overcome only 30 kilometers per hour.
Chest bone structure
The first factor, which excludes the possibility of flights of these giant birds, is the physiological structure of their chest cells. When compared with other birds, the absence of a specific outgrowth called keel becomes apparent. Studying bird skeletons, botanists noted the plane of the ostrich breast. This means that the pectoral muscles have nothing to fasten.
The feature of the functional located in the thoracic bone keel is:
- strengthening the sternum,
- protecting vital organs,
- the possibility of fastening a muscular corset involved in movements of the forelimbs or wings,
- mobility of the thoracic skeleton, which affects the depth and frequency of breathing,
- ability to change the trajectory during the flight.
The second reason why ostriches are deprived of the ability to soar in the sky follows from the physiological features of their skeleton. Since there is no bone growth in the fastener that is actively involved in the movements of the muscles, the soft fibers present are very weak. Moreover, due to the nuances of the structure, they can no longer develop. And to guarantee the flight and good wingspan can only strong, strong muscles attached to the keel.
Moreover, on the underdeveloped ostrich wings, the plumage is characterized by a primitive structure. Feathers of this bird, including flywheels and helmsmen, differ in curliness and friability. They are more like fluff. Botanists explain this nuance by the lack of connections between the beards, which is an obstacle to the formation of dense plates-webs. Since the ostriches lack a keel, and with it the protection of vulnerable internal organs, a kind of thickened corn has formed on the surface of the sternum. It performs the function of support when the bird lies on the ground.
The third factor affecting the impossibility of flying ostriches is their heaviness. In the area, mature females with a growth of 2.7 meters weigh about 100 kg, and well-fed males - within 135–150 kg. Weights add feathered and massive two-fingered legs. They differ from other winged individuals not only by their excessive thickness, length, but also by their internal structure.
Scientists have discovered that the tubular bones of flying representatives of the fauna are very light, and their composition is saturated with lime salt. The ostriches are different. Their bone tissue is completely devoid of air cavities, with the exception of the hips. In the process of evolution, due to the underdevelopment of the wings, the load on the hind limbs increased. As a result, the end of the pubic bones grew together and formed a closed pelvis, which is uncharacteristic of flying birds. In addition, on one of the ostrich fingers there is a small “hoof” that functions as a support. Overgrown bones began to grow and develop.
Did ostriches fly before: bird evolution
Little is known about the origin of the giant flightless birds. Modern systematics ornithologists and evolutionists are pushing two radically different versions of their appearance. According to the first, all ostrich-like animals originate from the middle of Cenozoic, developing on different continents, regardless of their ancestors. And adherents of the second theory claim that the birds of this series have one ancestor, which existed along with dinosaurs during the Mesozoic period. Genetic studies also confirm this theory.
Scientists believe that this ancient ancestor of all species of ostriches is the now extinct bird (Lithornithiformes), which lived about 55 million years ago. Her petrified remains were found in Europe and North America. Consequently, ostriches originally possessed the ability to fly. In this way they spread to all continents of the globe.
A giant feathery needed a large takeoff run. That is why, according to evolutionists, the habitat of ancient ostrich-like birds narrowed. In addition, they did not know how to run fast and take off abruptly, as a result of which they became easy prey for predators. Therefore, winged heavyweights had to look for affordable methods of salvation.
As it turned out, the flight, if necessary, survival rescued much more often than flying. The new generation of chicks was given only by those who refused wings.
In the process of evolution, giant muscular legs began to develop in giant birds, and the wings ceased to fulfill their original purpose. This genetic trait was fixed with each new brood. As a result, the front limbs of modern ostriches are poorly developed. They are characterized by two fingers with claws at the ends and beautiful curly plumage.