1) the development of the brain led to the building of nests and caring for the offspring. The development of the cerebellum provided good spatial coordination;
2) the emergence of a four-chambered heart with complete division of blood into arterial and venous;
3) the occurrence of warm-bloodedness and an increase in the level of metabolism;
4) fusion of some parts of the skeleton, the presence of cavities in it and the appearance of wings;
5) a general decrease in body weight (due to the facilitation of the reproductive organs, the characteristics of the excretory system).
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.