Do you ever lie awake at night pondering the fate of Crotalus willardi obscurus? If so, you have something in common with Byron Wusstig, acting curator of ectotherms at the Los Angeles Zoo. Of course, most readers will never have heard of this little-known reptile, but Wusstig and his colleagues are hoping to change that. The L.A. Zoo, with its vast experience in keeping and breeding rattlesnakes and other vipers, has joined a very exciting project to help repopulate obscurus (commonly known as the New Mexico ridge-nosed rattlesnake) back into parts of its historic range, where it has all but disappeared.