Until almost 50,000 years ago, huge birds were pacing through Australia: the thunderbird Genyornis newtoni, sometimes also called megagans, weighed up to 230 kilograms and was more than two meters high and thus significantly more massive than today's emus. But then the animals died out, like many other representatives of the Australian megafauna, probably due to a combination of over-hunting and climate changes. But at least for Genyornis newtoni, an illness could have caused the end. This is suggested by bone finds from sediments of Lake Callabonna, which Phoebe McInerney from Flinders University and her research group present in the "Papers in Palaeontology".
In at least four animals, the team found traces of osteomyelitis: an illness caused by bacteria, mycobacteria or fungi caused the bones inflamed and leads to abnormal growth or hollows in the skeleton. It is a very painful process that significantly limits mobility and thus also the search for food and water. Ten percent of the individuals found in Lake Callabonna were affected. However, the actual number could have been much larger, since Mcinerney and Co could not examine all the bones with the necessary effort.
The number of sick animals was nevertheless remarkably high, since the disease occurs today in birds only very sporadically, writes the working group. Osteomyelitis occurs when, for example, bacteria infect the bone tissue after fractures or pass from inflamed muscles. The disease probably hit a weakened population at the time: 48,000 years ago, a series of severe droughts began, shrinking lakes and forests and growing drylands in large parts of Australia.
Due to the lack of food and water, the thunderbirds also had to roam further, which weakened them and made them more susceptible to diseases. Freshly exposed mud areas on the lakes made it difficult to access the water and caused the animals to get stuck. This is one of the reasons for the great fossil wealth at Lake Callabonna. Drought and epidemics could therefore have caused the thunderbirds as well as the hunting and eating of the eggs by the Aborigines, which is also evidenced by sites of discovery.
