Mammals
​1.Mammary hair and glands are for different use in different environmental conditions
2. Mammals have a closed circulatory system to keep blood out of their tissues.
3. Monotremes are types of mammals that lay eggs.  Marsupial mammals carry their offspring in a pouch. Placental mammals are mammals who most give birth to their offspring. 

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Amphibians

Amphibians reproduce sexually. Amphibians have two circulatory routes, one for oxygen to go to the lungs and skin, and another to the rest of the body.

Reptiles

Reptiles have an amniotic egg to protect their embryos from the harsh weather. Scales give them a form of protection.  They produce sexually and have a closed circulatory system. 

Birds

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