Birds are the feathered friends of man. Their role in nature is invaluable. Read about their origin, meaning and protection in the article.
Birds: general characteristics
Birds are highly organized warm-blooded animals. In nature, there are nine thousand species of modern birds. Characteristic features of the class are the following features:
- Feathers.
- Hard beak from the cornea.
- No teeth.
- A pair of forelimbs turned into wings.
- The chest, pelvic girdle and the second pair of limbs have a special structure.
- The heart consists of four chambers.
- There is an air bag.
- Bird hatching eggs.
Birds, the general characteristics of which are presented above, thanks to the listed features are able to fly. This is what distinguishes them from other classes of vertebrate animals.
Appearance on earth
The origin of the birds is explained by severaltheories. According to one of them is supposed to live feathered trees. At first they jumped from branch to branch. Then they slid, then made small flights within the same tree, and finally learned to fly in open space.
Another theory suggests that the originbirds associated with ancestors of birds, which were reptiles with four legs. As the scales evolved, they became feathers, which allowed reptiles to jump, flying a short distance. Later, the animals learned to fly.
The origin of birds from reptiles
Опираясь на эту теорию, можно сказать, что the ancestors of birds were also creeping reptiles. At first their nests were on the ground. This attracted predators, which constantly destroyed nests together with chicks. Taking care of their offspring, reptiles settled in the thick of tree branches. At the same time, a hard shell began to form on the eggs. Before that, they were covered with film. Instead of scales appeared feathers, which served as a source of heat for eggs. The limbs are longer and covered with plumage.
The origin of birds from ancient reptilesobviously, as scientists believe. Ancestors of birds begin to take care of their offspring: they feed the chicks in the nest. To do this, solid food was crushed into small pieces and put it in the beak of kids. Possessing the ability to fly, the primitive birds of the ancient time period could better defend themselves against the attack of their enemies.
Ancestors - waterfowl
The origin of birds, according to another theory,associated with their aquatic counterparts. This version owes its existence to the remains of ancient birds that were found in China. According to scientists, they were waterfowl and lived more than a hundred million years ago.
According to theory, birds and dinosaurs lived togethersixty million years. Among the finds were feathers, muscles, membranes. Exploring the remains, paleontologists made the following conclusion: the ancestors of ancient birds swam. To get food from the water, they dived.
What do birds and reptiles look like?
If you study the origin of birds, the similarities betweenIt is not difficult to find them and representatives of other classes. Plumage is the most noticeable feature of the appearance of birds. Other animals do not have feathers. This is the difference of birds from other animals. Signs of similarity are as follows:
- Пальцы ног и цевка у многих птиц покрыты scales from the cornea and shields, like reptiles. So the scales on the legs can replace feathers. Characteristically, the rudiments of feathers in birds and reptiles do not differ. Only birds then develop feathers, and reptiles develop scales.
- Exploring the origin of birds, features inthe resemblances to which are incredible with reptiles, scientists have determined that the jaw apparatus is more prominent. Only in birds it turned into a beak, while in reptiles it remained the same as in turtles.
- Another sign of the similarity of birds and reptiles -skeletal structure. The skull and spine are articulated with only one tubercle located in the occipital region. Whereas in mammals and amphibians two bumps are involved in this process.
- The location of the pelvic girdle of birds and dinosaursthe same. This is seen in the fossil skeleton. This arrangement is due to the load on the pelvic bones when walking, since only the hind limbs are involved in holding the body.
- Birds and reptiles have a four-chamber heart.In some reptiles, the septum of the chambers is incomplete, and then the arterial and venous blood are mixed. Such reptiles are called cold-blooded. Birds have a higher organization, compared to reptiles, they are warm-blooded. This is achieved by removing the vessel that carries blood from the vein into the aorta. In birds, it does not mix with the arterial.
- Another similar feature is egg hatching. This is typical of pythons. They lay about fifteen eggs. Snakes curl up over them, forming a kind of canopy.
- Most birds look like reptilesembryos, which in the first stage of their development are similar to fish-like creatures with tails and gills. This makes the future chick look like other vertebrates in early stages of development.
Differences of birds from reptiles
When paleontologists study the origin of birds, they compare the facts and findings collected bit by bit, and find out how birds are similar to reptiles.
What are their differences, read below:
- When the birds appeared first wing, they began to fly.
- The body temperature of the birds does not depend on external conditions, it is always constant and high, while the reptiles fall asleep during cold weather.
- In birds, many bones are spliced, they are characterized by the presence of a bobbin.
- Birds have air bags.
- Birds build nests, hatch eggs and feed chicks.
Pervoptitsy
Currently found fossilsancient birds. After careful research, scientists have concluded that they all belong to the same species that lived a hundred and fifty million years ago. These are Archeopteryxes, which means “ancient fin”. Their difference from today's birds is so obvious that Archeopteryx was allocated in a separate subclass - lizardbirds.
Little studied ancient birds.The general characteristic is reduced to the definition of the appearance and some features of the internal skeleton. Pervoptitsa different small size, about as modern forty. Her forelimbs had wings, the ends of which ended in three long fingers with claws. The weight of the bones is large, so the ancient bird did not fly, but only crawled.
Habitat - coastal areas of marinelagoon with dense vegetation. Jaws had teeth, and tail - vertebrae. There are no links between Archeopteryx and modern birds. The first bird were not the direct ancestors of our birds.
Value and protection of birds
The origin of the birds is of utmost importance inbiogeocenoses. Birds are an integral part of the biological chain and participate in the circulation of living matter. The food of herbivorous birds is fruits, seeds, green vegetation.
Different birds play different roles.Grain - eating seeds and fruits, some species - store them, carrying over long distances. On the way to the place of storage, the seeds are lost. So is the resettlement of plants. Some birds have the ability to pollinate them.
Great role in the nature of insectivorous birds. They control the number of insect populations by eating them. If there were no birds, the destructive activity of insects would be irreparable.
Человек, по мере своей возможности, охраняет птиц and helps them survive the harsh winters. People everywhere hang temporary nests. In them tits, flycatchers, azures live. Winter periods are characterized by the absence of natural fodder for birds. Therefore, birds should be fed, filling the nesting place with small fruits, seeds, bread crumbs. Some birds belong to commercial species: geese, ducks, grouse, wood-grouse, and black grouse. Their value to man is great. Sports interest are woodcocks, sandpipers, snipe.
Interesting Facts
Из глубины веков:The body and legs of Archeopteryx were covered with long feathers, three and a half centimeters. It can be assumed that the bird did not swing its legs. Feathers were inherited from ancestors who lived in more ancient times and used all four wings when flying.
Today: filling the nesting of birds with food, you need to make sure that the salt does not get there. It is a white poison for birds.
