Mammals are the only creatures to feed their young on mother's milk.
a few but not all and i only have one to share with you, the bat
only people have a menstrual cycle but mammals have something called Estrous cycle and there is sometimes bloody discharge. fish are not mammals and they don't have it.
Birds and mammals are air breathers. Lampreys are not.
Dinosaurs are more closely related to mammals. Both mammals and dinosaurs share a reptilian ancestor that they don't share with amphibians.
They all have mammalia and nipples.
Dolphins are warm blooded like other mammals.
Only mammals nurse their babies.
I would never have thought that rabbits had anything to do with whales let alone evolve into them. The only similarity that they share is that they are both mammals.
they share common characteristics: fur mammals rounded ears food the only huge difference is the color of their fur.
urethra
Just the bat.
there all mammals