Genyornis newtoni, an Australian Pleistocene giant, had a common and severe bone infection.
Genyornis newtoni, the last of Australia’s legendary giant birds – the dromornithids or ‘Thunder Birds’ – encountered the ultimate survival test right before they became extinct, suggests a rare fossil finding by Flinders University researchers in South Australia.
The discovery, which was published in the journal Papers in Palaeontology, depicts serious bone infections in multiple Genyornis fossils discovered in the 160-square-kilometer salt lake beds of SA’s Lake Callabonna fossil site, roughly 600 kilometers northeast of Adelaide.
The 230 kg Genyornis weighted around 2 m tall and weighed 5 to 6 times as much as an emu.
Getting stuck in the dangerous muddy bed of Lake was not Genyornis’ only worry, according to the study. Some had a severe bone disease that would have restricted their mobility and foraging, according to Phoebe McInerney, a Flinders University researcher and lead author on the project.
“The fossils with signs of infection are associated with the chest, legs and feet of four individuals. They would have been increasingly weakened, suffering from pain, making if difficult to find water and food,” she adds.
“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.”
The study discovered that roughly 11% of the birds had osteomyelitis, a serious bone infection.
“We see frothy and woven bone, large abnormal growths and cavities in their fossil remains,” Miss McInerney says.
Multiple individuals with osteomyelitis in a community is unusual in any birds. This shows that the occurrence was generated by a more complicated situation.
Associate Professor Lee Arnold of the University of Adelaide dated the lake sediments where Genyornis was discovered. This connects the deaths of these individuals to a period of severe drought that began around 48,000 years ago.
During the drought, these massive birds, as well as other megafaunal animals such as wombats and kangaroos’ old cousins, faced severe environmental challenges.
The great inland lakes and forests began to disappear as the landscape dried across Australia, and central Australia became flat desert plains now covered with salt lakes.
“As the drought conditions worsened, food resources would have been reduced, placing considerable stress on the animals”, adds co-author Associate Professor Trevor Worthy, from Flinders University’s Palaeontology Laboratory.
“From studies on living birds, we know that challenging environmental conditions can have negative physiological effects, so we infer that the Lake Callabonna population of Genyornis would have been struggling through such conditions.”
The repercussions of severe drought periods appear to have included high rates of bone infection in the Lake Callabonna population. Individuals who were weaker were more prone to become entangled in the deep muds of Lake Callabonna and perish.
Because there is no solid evidence that Genyornis newtoni survived much longer than this, it is likely that prolonged drought and high disease rates contributed to the species’ final extinction.
“We now know more about the lives and deaths of these birds compared to 125 years ago when they were first described,” the authors conclude.
Image Credit: Flinders University
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