Birds and reptiles belong to science to two of the five famous classes of terrestrial vertebrates, or fourlegged classes.
If we talk about the external characteristics of birds and reptiles, then it would seem that everything is definitely here: no one will ever confuse the bird and lizard. However, if we consider in more detail, then we can detect of interesting features of the structure of the body, which are similar to these two classes, and it was precisely this similarity that made it possible for scientists to conclude about their related origin.
Scientists suggested that the ancestors of birds could be just ancient reptiles moving on their hind legs and living on trees.
General features of birds and reptiles
The similarity of birds and reptiles is not so unambiguous, but it is still present:
If we talk about the skin of reptiles, then it is dry, with a keratinized epidermis, as a result of which it is absolutely devoid of any glands, with the exception of the glands of special prescription (for example, femoral pores or musky glands) with horn scales of a variety of structure.
The skin of birds is quite similar in its structure with reptiles: their skin is also devoid of glands (the exception is usually coccygeal iron), but it is still more mobile and much thinner. Horn scales, like reptiles, have birds only on the legs, and on the body they are replaced with feathers.
Differences of two types
The fact that birds are evolutionarily above the reptiles may indicate the size of their brain, namely the significant dimensions of the large hemispheres (including the cerebellum).
The same conclusion can be drawn from the structure of some systems of birds and reptiles:
Various veins of the body (albeit with a certain similarity): these are scales and feathers.
Comparative table of birds and reptiles
|one||Number of species||7 000||9,000|
|2||The ability to fly||Not characteristic||Characteristic|
|3||Body dimensions||From 1 cm (hidden scythe) to 7 m and mass 1 t (Nile crocodile), lengths 11.47 m (anaconda)||From 2.8 cm (hummingbird-shmel) to a height of 2.8 m and mass 150 kg (African ostrich)|
|four||Front limbs||Fivefingered||They have the appearance of wings|
|5||Glands||Absent||There is a coccygeal gland|
|6||The skin is covered||Horn, scales or shields||Feathers|
|7||Features of the structure of the skeleton||Interdemonth and interpretable compounds||Lightness and strength, bone growth (for example, in the skull)|
|9||The growth of the vertebrae||Missing||Observed (complex sacrum)|
|eleven||Muscles||Less differentiated, the bulk is located on the back of the body, muscles that provide the movement of the limbs located on the limbs||More differentiated, the bulk is located on the chest (the chest muscles are highly developed), muscles that provide the movement of the limbs located on the body|
|fourteen||Stomach||Well expressed, has a strong muscles||2 departments: glandular and muscular stomach|
|fifteen||Colon||Relatively longer||Relatively shorter (the detention of the calf masses would make it difficult to fly)|
|16||Fabrice bag||Missing||There is (has the form of blind outgrowth of cloaks)|
|17||Airways||Nostrils, larynx, trachea, two bronchi||Nostrils, nasal cavity, upper larynx, trachea with a voice apparatus in the lower larynx, bronchi|
|eighteen||Lungs||Have a relatively smaller surface area (cellular)||Have a relatively large surface area (spongy)|
|twenty||Air bags||Absent||There is|
|21||Type of breathing||Ordinary||Double|
|22||The total volume of blood||Up to 7% body weight||Up to 9% body weight|
|23||The content of red blood cells in the blood||0.98 million/mm3||3.5 million/mm3|
|24||Oxygen container of blood||Up to 12%||Up to 22%|
|26||Aortic arcs||There is the right and left arches of the aorta||There is only the right aortic arc, the left is reduced|
|27||Mixing blood||Occurs to mix arterial and venous blood||Does not occur (blood flow is separated from the venous)|
|28||Body temperature||Unstable (coldblooded)||Relatively constant (warmblooded)|
|thirty||External ear||Missing||There is (auditory passage)|
|31||Women’s sexual system||Symmetric (paired ovaries and eggs)||Asymmetric (there is only the left ovary and the left oviduct)|