I wonder when Marines began to sail on ships. I can recall Thucydides mentioning marines on board Athenian ships during the Peloponnesian War. I am sure they date at least to 500 B.C., and probably longer.
There have been Marines about as long as there have been warships. They were originally (and in some countries still are) referred to as Naval Infantry, and primarily served as boarding and landing party specialists, with their ground combat duties a natural extension of that.