DreadPirateMurphy said:
http://www.flmnh.ufl.edu/cnhc/potm-jun00.html
Metal boat bitten by a crocodile.
Not armor, but still, a bite by a fairly small croc into a metal hull. Scale that up for Mr. Dragon. Suffice it to say that I will NOT be volunteering to put on the "dragon suit" and get lowered into a dragon's lair with a camera.
Thats a pretty cool picture, and rather amazing, but I would still be willing to be thats probably aluminum, I guarantee you it's not tempered steel.
Tempered steel and even iron is some amazingly hard and strong stuff. Much stronger than most people realise.
I think even a large predator would end up unhappy after trying to bite through it. I bet that alligator would break it's jaw and / or teeth before puncturing a tempered steel vambrace let alone breast plate. (of course he could always just seize it and roll over and over until the arm came off...)
I believe the best European body armor that existed historically could withstand the attack of any of the numerous quite fearsome predators which exist in the real world, including bears, tigers, lions, wolves, sharks and even 20 foot saltwater crocodiles.
(I'm not so sure about an elephant or a rhino though)
Having said that, I grant you in D&D there are monsters considerably larger than any of the above, some with magical powers. Luckily for the denizins of D&D lands they are fairly few and far between
I don't think any body armor anyone could invent could hold up to a 150' dragon.
What I bet you would see if there were dragons like that in the Real World are some really interesting war machines of the type Leonardo Davinchi experimented with. Self propelled armored turtles with all sorts of torsion powered ballistae, greek fire projectors, and
plenty of spikes. Maybe even things like pincers and blades (they were able to accomplish some pretty amazing things with clockwork and gears in those days.)
I bet you would see some pretty fantastic dragon hunting machinery, and a whole different type of fortification for castles.
I wouldn't put my money on the dragons either, humans are like something in between fire ants and really, really mean monkeys....with tools. They are incredibly persistant and hostile and endlessly inventive and no species on earth has even come close to standing up to them.
BD