Giant kangaroos lived during the Pleistocene period (2 million to 10,000 years ago). On the Australian grassland were roaming large herds of giant kangaroos up to 10ft. Tall. They were wiped out, along with the entire fauna of giants, 40,000 years ago. First thought to be because of people entering Australia, new evidence has come to light that it was a series of devestating droughts which may have played a bigger factor.