Australia's burrowing echidna evolved from a water-dwelling ancestor in an "extremely rare" biological event, scientists said ...

Australia's burrowing echidna evolved from a water-dwelling ... echidnas are well suited to a life shuffling through the forest undergrowth.

Australia's burrowing echidna evolved from a water-dwelling ancestor in an "extremely rare" biological event, scientists said Tuesday in a new study of the peculiar egg-laying mammals.