Erythropoiesis (from Greek 'erythro' meaning red and 'poiesis' meaning to make) is the process which produces red blood cells (erythrocytes).
Birds and mammals have the following characteristics in common: they are vertebrates, meaning they have an internal skeletonthey are warm-bloodedthey breathe using lungs, so â¦ have full respiratory systems they have circulatory systems. Most mammals give live birth, but there is a sub-group known as monotremes, which are the egg-laying mammals. 2  This group includes just the platypus and the echidna. 3  They are still mammals because, like all mammals, they feed their young on mothers' milk.
Feathers have three functions: flight, temperature regulation and display. Most birds have hollow main bones with air sacs in them. This makes them lighter and makes flight easier. Birds are bipedal: they have two legs which are often covered with scales (small, flat plates which over-lap in the same way as feathers). They have a hard beak with no teeth. Because birds keep a high body temperature, they use lots of energy. So, they need to eat a lot of food compared with their weight.