Even zinc and iron coins live longer than the largest reptiles. Heck, a gold coin from the Jurassic Era would be pristine today. You can put a coin in a bezel and wear it for jewelry. If the market really rises, or if a coin is ruined, you can sell the numismatics for scrap metal. There isn't much you can do with a dead reptile.
Philatelists can relate to numismatists.
The US Dairy Council will never understand salamanders, newts, or rattlesnakes.