Brown bears did not suffer the same fate as cave bears and have survived until today.

BBC: Early human 'squatters' drove cave bears to extinction

The team found that cave bears went into decline 50, 000 years ago, before finally going extinct 24, 000 years ago.

BBC: Early human 'squatters' drove cave bears to extinction

As cave bears and wolves from a few million years ago were bigger than their descendants, they were probably quite a bit slower than they are today.

ECONOMIST: Controlling the size of predators

And, although he is proposing to start with cave bears and woolly rhinoceros, Sid, Diego and even Scrat may yet get their turn on the genetic catwalk.

ECONOMIST: The genetics of mammoth coat colour