The thyacine or Tasmanian tiger, terror of the island's first white settlers, was a kind of carnivorous kangaroo with the jaws of a wolf and a taste for sheep. Ruthlessly slaughtered, the creature became officially extinct 60 years ago, when the last known tiger died in a zoo -- but since then, there have been over 300 sightings. Here zoologist Juliet Vickery ventures into the Tasmanian forests to check out the evidence.