why can reptiles birds and mammals reproduce successfully on dry land?

Answer 1

What about this confuses you? Reptiles hatch eggs so the eggs are fertilized whether they are buried in a sand pit or left in the brush by the river bank. Birds also have eggs, and I believe for them, at least the small varieties that fly, a lot of the mating ritual happens during flight. And mammals are naturally land creatures, except whales and dolphins who are ocean animals but mammals too because they birth live young...so there's the flaw in your question. ocean mammals need/require water.

Answer 2

Fish and amphibians have shell-less eggs that need to be kept wet or they will die. Birds and reptiles have a solid shell that reduces the movement of water into and out of the egg. Mammals incubate their young internally and regulate fluid and air in the fetus through the mother.

Answer 3

I suppose that if many of them tried to reproduce in water, they'd drown. lol

Answer 4

Look up amniotic egg.