January 13, 2016 7.10pm GMT
Australia is renowned for once being home to a group of gigantic birds known as the mihirungs. These birds are distantly related to waterfowl and included the impressive Dromornis stirtoni, the largest bird ever known on the planet at about 450kg in weight.
They were around about eight million years ago and the last surviving relative lived into the last 100,000 years in what is termed the Pleistocene. This was Genyornis newtoni, and at 250kg it was still a massive bird, some six times the weight of an emu. It is listed among the megafauna that went extinct after human arrival.
Fossil eggshell has been found eroding from sand dunes in widespread localities across Australia. And in the early 1980s, one particular kind – about as thick as that of emu – was noticed to differ from that of emu. It was believed to beGenyornis shell.