Nothing. Mammals can be as small as a mouse or large as a whale.
The blue whale is the biggest mammal.
If you mean "Manatee" , it is a mammal.
a mammal mean a animal fish bird insects and reptiles
no.
If you mean SKUNK, yes that is a mammal.
The first dinosaur was about the size of a horse.
No it does not mean that it is a mammal. It is a carnivorous fish.
I think you mean; How do you know if a type of animal is a mammal? Am I correct?
If every mammal was the same size, it would be hard to hide from the predator or stalk the prey. Every mammal is the size it needs to be to survive.
The elephant probably
The pygmy shrew is Ireland's smallest mammal. About half the size of a field mouse.
Do you mean cygnet? If so this is a baby swan. So it is a bird not a mammal.