There's been this species in the back of my head for quite a while, but it's not really a complete finished species, or anything...
Think of it as essentially a canine species that have completely evolved for nocturnal life and hunting. All their fur is pitch black, eyes oversensitive to adjust to nighttime conditions meaning that their pupils become absoluty tiny in daylight, somewhat enlargened ears, capable of using echolocation, a small flap grown over their nose that acts as a sort of amplifier for a whistling noise they can make with their nose for echolocation.
I dunno, just something to help you get ideas, maybe?
