It ran like a wolf. It waded like a hippopotamus. It put its ear to the ground to hear distant rumbles. It had the ankles of a cow. But above all, it had the ear bones of a whale. In a find that matches the discovery of archaeopteryx - one of the great missing links of evolution - researchers in Pakistan have unearthed many of the bones of the 50m-year-old Pakicetus attocki, a land-dwelling, estuary-wading, meat-eating ancestor of the whale.