This reptile just left its tail behind. About two hundred and eighty-nine million years ago.
The hunter got a mouthful of tail. The reptile got away.
This is Captorhinus, in what is now Oklahoma. Its world was full of bigger hunters.
Its bones washed into caves there. Scientists studied seventy tail bones from Captorhinus and its relatives.
Across the middle of each bone runs a line. It is not a break. The bone grew that way, with a weak spot built in.
Grab the tail, and it snaps along that line. Living lizards use the same trick.
But this is not a lizard. Lizards came much later, and scientists think they found the trick again, on their own.
The young could do it best. In bigger, older animals, bone filled the line in, and the trick seems to have faded.
There is no sign it ever grew a tail back. A tail, for a life. The oldest known trade of its kind.
