In my experience, one of the most common way to differentiate species/race in US fantasy larps is a combination of skin color (blue, green, orange, furry), and ears (round or pointy). Skin color is somewhat understandable- after all, if you can see color, there is an awful lot of skin to work with and body paint is relatively inexpensive. (Plus, you know, history.) But why ears?
Even a cursory look at world folklore shows that pointy ears show up here and there. It’s not original to the larp scene. Nevertheless, horns and unusual hair color show up in folklore, but neither have the popularity of ears in the larp scene. Hm.
In the practice of otoplasty, the term prominent ears describes external ears (pinnae) that, regardless of their size, protrude from the sides of the head. The abnormal appearance exceeds the normal head-to-ear measures, wherein the external ear is less than 2.0 cm, and at an angle of less than 25 degrees, from the side of the head. Ear configurations, of distance and angle, that exceed the normal measures, appear prominent when the man or the woman is viewed from either the front or the back perspective. (source; boldface added)
My personal, totally unscientific theory is that ears are a popular prosthetic because their altered silhouette is visible from any angle. Even skin color doesn’t have this advantage; all cats look grey in the dark only makes sense as an idiom when you belong to a species that has reduced color vision at night, and humans do!
This distinctive silhouette, combined with the tendency to look at people’s faces, means that the relatively small change to their shape results in an easily and consistently noticed difference. What do you think?
Also, Medieval Collectibles has a great ear selection.