Chain-mails aren't exactly the same thing as small overlapping plates, which is what I've seen in game. Not sure if that's what you mean though.

Duskhorn chainmail exists.

While one could theoretically meld horn in to rings, there's very little historical evidence that anyone thought this was a good idea in reality. Given the materials Zalanthans have at their disposal, scale or lamellar armors made from small plates of bone, horn, or shell is a much better idea. Hence why there's a fair bit of it in game.

One thing that could be seen more of in game is linen armor.

http://en.wikipedia.org/wiki/Linothorax

I've seen it in game but don't know if the item matched up to historical levels of effectiveness. Something that could provide decent protection against bronze age weapons (i.e. metal weapons) would probably be pretty fucking good versus a guy with a flint axe or a wooden sword. Obsidian blades, not so much.

Yeah, but it says it was reinforced by metal... one could, however, use something like say, oh, hardened leather instead.

Bone ringmail makes a lot more sense to me than something like 4-in-1 chainmail.