Evolutionary Defense: Science Fiction/Horror

It was always a wonder why the birds had huge spiky ruffs around their necks and legs. The ruffs looked ridiculous, and they got in the way. Evolutionary biologists were profoundly baffled, and many wrote theses on how this might possibly have been useful and/or on a more utilitarian approach to evolution--namely, sometimes stuff just happened and it took a while to get phased out. Some theorized that there was an element in the diet or in the environment that triggered whatever gene pattern was linked to the ruffs, that there was something else that was of benefit that couldn't be seen, and the ruff was just a side effect. Of course, that was long before the true reason showed up.

Inspiration: Science News blurb: "Back off, extinct moa 8.19.09 - Leaf color and shape may defend a New Zealand tree species from a long-gone giant bird"
Story Potential: High.
Notes: Though it's only set-up, not an actual plot, I like the idea of biologists thinking some odd defensive adaptation is in response to an extinct threat, or being baffled by it, only to figure out that it really is a response to a threat that is not extinct at all. Might be a fun opening to a story with a scientist main character.