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.
Birds are vertebrate animals that have feathers, wings, and beaks. Like all vertebrates, they have bony skeleton. Most birds are able to fly, but some (like ostriches and penguins) cannot fly even though they still have wings. Other kinds of animals like insects and bats can fly too, but birds are the only animals with feathers. Birds have scales on their lower legs and feet, like reptiles. All birds reproduce by laying eggs with hard shells, and most build nests to help protect the eggs from weather and predators.