What do the covers of reptiles and birds have in common?

1) The covers of reptiles and birds have a common origin.
2) Reptile scales and bird feathers are formed from the connective tissue layer of the skin.

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.