Birds are man's feathered friends. Their role in nature is invaluable. Read about their origin, meaning and protection in the article.
Birds: general characteristics
Feathers are highly organized warm-blooded animals. In nature, there are nine thousand species of modern birds. The characteristic features of the class are the following features:
- Feathers.
- Hard corneal beak.
- No teeth.
- Pair of forelimbs transformed into wings.
- The chest, pelvic girdle and the second pair of limbs have a special structure.
- The heart has four chambers.
- Air bag included.
- The bird incubates the eggs.
Birds, the general characteristics of which are presented above, due to the listed features are able to fly. This is what distinguishes them from other classes of vertebrate animals.
Appearing on earth
The origin of birds is explained by several theories. According to one of them, birds are supposed to live on trees. First they jumped from branch to branch. Then they glided, then made small flights within the same tree andfinally learned to fly in open space.
Another theory suggests that the origin of birds is connected with the ancestors of birds, which were reptiles with four legs. Evolving, the scales became feathers, which allowed the reptiles to jump, flying a short distance. Later, the animals learned to fly.
The origin of birds from reptiles
Based on this theory, we can say that the ancestors of birds were also crawling reptiles. At first their nests were on the ground. This attracted predators, who constantly destroyed the nests along with the chicks. Taking care of their offspring, the reptiles settled in the thick of tree branches. At the same time, hard shells began to form on the eggs. Before that, they were covered with a film. Instead of scales, feathers appeared, which served as a source of heat for the eggs. The limbs became longer and covered with plumage.
The origin of birds from ancient reptiles is obvious, according to scientists. The 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 into the beaks of babies. With the ability to fly, the primitive birds of the ancient period of time could better defend themselves against the attack of their enemies.
Ancestral waterfowl
The origin of birds, according to another theory, is associated with their waterfowl counterparts. This version owes its existence to the remains of ancient birds that werefound in China. According to scientists, they were waterfowl and lived more than a hundred million years ago.
According to the theory, birds and dinosaurs lived together for sixty million years. Among the finds were feathers, muscles, membranes. Examining the remains, paleontologists made the following conclusion: the ancestors of ancient birds swam. To get food from the water, they dived.
How are birds and reptiles alike?
If you study the origin of birds, it is not difficult to find similarities between 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 between birds and other animals. Similarities are as follows:
- The toes and tarsus of many birds are covered with corneal scales and scutes, like those of reptiles. So the scales on the legs can replace feathers. It is characteristic that 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, the features of which are incredible in resemblance to reptiles, scientists have determined that the jaw apparatus is more noticeable. Only in birds it turned into a beak, while in reptiles it remained the same, like in turtles.
- Another sign of the similarity of birds and reptiles is the skeletal structure. The skull and spine are articulated by only one tubercle located in the occipital region. Whereas in mammals and amphibians, two tubercles are involved in this process.
- The location of the pelvic girdle of birds and dinosaurs is the same. This isseen from the skeleton of the fossil. This arrangement is associated with 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-chambered heart. In some reptiles, the septum of the chambers is incomplete, and then arterial and venous blood mix. Such reptiles are called cold-blooded. Birds have a higher organization than reptiles, they are warm-blooded. This is achieved by eliminating the vessel that carries blood from the vein to the aorta. In birds, it does not mix with arterial.
- Another similar feature is incubation of eggs. This is typical for pythons. They lay about fifteen eggs. The snakes curl up above them, forming a kind of canopy.
- Most of all, birds are similar to reptile embryos, which in the first stage of their development look like fish-like creatures with tails and gills. This makes the future chick look like other vertebrates in the early stages of development.
Differences between birds and reptiles
When paleontologists study the origins of birds, they compare facts and findings piece by piece to find out how birds are similar to reptiles.
What are their differences, read below:
- When birds got their first wings, they started to fly.
- The body temperature of birds does not depend on external conditions, it is always constant and high, while reptiles fall asleep during the cold season.
- In birds, many bones are fused, they are distinguished by the presence of a tarsus.
- Feathers have air sacs.
- Birds build nests, incubate eggs and feed chicks.
Firstbirds
Currently found fossil remains of ancient birds. After a thorough study, scientists came to the conclusion that they all belong to the same species that lived one hundred and fifty million years ago. These are Archeopteryx, which means "ancient feathers" in translation. Their difference from today's birds is so obvious that Archeopteryx was singled out in a separate subclass - lizard-tailed birds.
Ancient birds are little studied. The general characteristic is reduced to the definition of the appearance and some features of the internal skeleton. The first bird was distinguished by its small size, approximately like a modern magpie. Forelimbs she 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 marine lagoons with dense vegetation. The jaws had teeth, and the tail had vertebrae. No links have been established between Archeopteryx and modern birds. The first birds were not the direct ancestors of our birds.
Meaning and conservation of birds
The origin of birds is of great importance in biogeocenoses. Birds are an integral part of the biological chain and participate in the circulation of living matter. Herbivorous birds feed on fruits, seeds, green vegetation.
Different birds play different roles. Grain eaters - eat seedsand fruits, individual species - store them, transferring them over long distances. On the way to the storage place, the seeds are lost. This is how plants spread. Some birds have the ability to pollinate them.
The role of insectivorous birds in nature is great. They control insect populations by eating them. If there were no birds, the destructive activity of insects would be irreparable.
Man, as far as possible, protects the birds and helps them survive in harsh winters. People are putting up temporary nests everywhere. Titmouse, flycatchers, blue titmouse settle in them. Winter periods are characterized by a lack of natural bird food. Therefore, birds should be fed, filling the nesting place with small fruits, seeds, bread crumbs. Some birds are commercial species: geese, ducks, hazel grouses, capercaillie, black grouse. Their value to humans is great. Of sporting interest are woodcocks, waders, snipes.
Interesting facts
From time immemorial: Archeopteryx's body and legs were covered with long feathers, three and a half centimeters. It can be assumed that the bird did not swing its legs. The feathers were inherited from ancestors who lived in more ancient times and used all four wings when flying.
Today: Filling bird nests with food, you need to make sure that s alt does not get there. She is a white poison for birds.
