I am not sure what level answer you are looking for, I will assume basic. Mammals and birds are both warm blooded and are both vertebrate animals (have a backbone). Hope that helps.
They are all vertebrates: Females have two lateral vaginas, which lead to separate uteruses. A third canal, the median vagina, is used for birth. Males have a two-pronged penis, which corresponds to...
all have fur, all have live babies except for the platypus and all breathe air You are right on two counts; all mammals have hair/fur and give live birth. The final characteristic is that female...
Birds and mammals have the following characteristics in common: they are vertebrates, meaning they have an internal skeleton they are warm-blooded they breathe using lungs, so have full respiratory...
The main characteristic shared by mammals, and which makes them distinct from other vertebrate groups, is that they suckle their young on mothers' milk. This is the main characteristic mammals...