What the Heck is That?

Since we had a long weekend I finally got my Warhammer Glade Guard glued together, minus one tiny dagger that went MIA and has yet to turn up. I admit I thought about gluing the extra elf head to the belt of the dagger-less guard, but figured that probably wouldn't go over well with his buddies.

Meanwhile, however, I am left with another conundrum; there's a critter in the pack that isn't pictured anywhere; seen here in the lower left of my pic:

And here's a close-up of the lil guy, who looks a bit like a lizard with wings:

Seriously; what the heck is it? It's not on the website, not on the box, not in the book (that I can find, anyway); nowhere. So, what is it? Is it worth points, is it a mascot, a familiar, a minion? ("Who's my minion? Who's my minion?" sorry - D&D 4E reference there...) I just. don't. know.