Break a leg, they say in show business. We can handle that. But humans, despite being the rulers of Earth, can't regenerate lost appendages. It seems that the more advanced the species, the less able they are to regrow legs, claws or heads. So break a head. It's up to us to stop, think and make sure these species stick around, even if they can grow back lost limbs. Unfortunately, so far, there doesn't seem to be a species that can grow back from extinction.
Skinks are one example. They can't walk upright, but they can release their tail at will. If a predator tries to attack from behind, the tail detaches and keeps wiggling while the skink scurries away, according to the Missouri Department of Conservation. The skink can grow a new tail in three to four months. Alas, they are never "as colorful or elegant as the original," the agency says.