Bone disease killed off Australia's giant thunder birds

A new study published in the journal Papers in Paleontology has found that the huge Australian “thunder birds” (Genyornis newtoni) which were wiped out 48,000 years ago, suffered a painful form of bone infection that hampered their mobility and foraging abilities and possibly contributed to their extinction.

These majestic birds, living in the territory of today’s Australia, weighted roughly 230 kg (almost six time more than an emu), and were about two meters tall. They were part of a unique group of Australian flightless birds called the dromornithids or “thunder birds.”

By studying the fossils of these birds found at the famous South Australian fossil site of Lake Callabonna, scientists discovered that at least 11 percent of these birds suffered from osteomyelitis, a severe infection affecting multiple bones throughout the animals’ bodies.

“The fossils with signs of infection are associated with the chest, legs, and feet of four individuals,” said study lead author Phoebe McInerney, a doctoral student in paleontology at the  Flinders University in Adelaide. 

“They would have been increasingly weakened, suffering from pain, making it difficult to find water and food. It’s a rare thing in the fossil record to find one, let alone several, well-preserved fossils with signs of infection. We now have a much greater idea of the life challenges of these birds.”

Since this disease afflicted such a large percentage of the bird populations, researchers believe that it may have been caused by environmental stressors. As the Australian continent dried during a period of severe drought 48,000 years ago, large inland lakes and forests began to disappear and central Australia transformed into a flat desert. Thus, food resources most probably dwindled significantly, placing considerable stress on thunder birds and other Australian megafauna.

“From studies on living birds, we know that challenging environmental conditions can have negative physiological effects,” said study senior author Trevor Worthy, an associate professor of Vertebrate Paleontology at Flinders University. “So we infer that the Lake Callabonna population of genyornis would have been struggling through such conditions.”

According to Professor Worthy and his team, the effects of severe drought included high rates of bone infection, which may have ultimately contributed to the extinction of this fascinating species.

Image Credit: Phoebe McInerney

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By Andrei Ionescu, Earth.com Staff Writer