What it is
A living lizard. Many lizards can drop part of their tail when a hunter grabs it. The hunter is left holding the tail, and the lizard gets away.
Why it matters
More than half of all the families of living lizards and snakes use this escape. Captorhinus did something very like it about 289 million years ago. But Captorhinus was not a lizard, and lizards came much later. Scientists think lizards found the trick again, on their own.
Not quite the same break
In most lizards the break line runs right through the tail bone, top to bottom. In Captorhinus it ran only through the lower half. Many lizards grow back a stand-in tail around a rod of cartilage. There is no sign that Captorhinus ever could.