Australia officially has its first vulture or, at least, a very old, fossilised one after South Australian palaeontologists reclassified a specimen originally thought to have been an eagle.
Cryptogyps lacertosus (powerful hidden vulture) lived in Australia during the late Pleistocene, about 500 thousand to 50 thousand years ago.
But until now, its fossil has been classified as a prehistoric eagle.
Dr Ellen Mather, from Flinders University in Adelaide, led the study, which has been published in Zootaxa.
She explains that comparing the fossilised tarsometatarsi – or the lower leg bone – to that of modern eagles and vultures enabled the reclassification.
“We determined this through getting the fossil specimens and comparing them to as many species of living eagles and vultures as we could,” Mather says.
“In this case, it turned out these fossils were more similar to a vulture than they were an eagle, and placing them in an evolutionary tree supported that conclusion.”
Reclassification over a century later
The first bone of Cryptogyps – a wing-bone fragment – was found in 1901 near Kati Thanda-Lake Eyre in the north-eastern outback of South Australia.
British ornithologist Charles Walter de Vis in 1905 dubbed the fossil Taphaetus lacertosus (meaning powerful grave eagle), in the belief it was a predecessor of the wedge-tailed eagle (Aquila audax).
“And given that this was over 100 years ago, I don’t know that [de Vis] necessarily had all specimens on hand to do full-on comparisons,” says Mather.
“He was mostly comparing the fossils he had, to material from other birds in Australia at the time.”
The reclassification of the specimen as Cryptogyps is the result of Mather’s studies into describing fofossilised eagles and connecting them with their modern descendants.
She identified that the fossil had less pronounced phalanges – or toe bones – than would be expected from ancestors of today’s eagles.
That lends itself to an animal less inclined to attack live prey, and more likely to peck at a dead carcass.
“On the eagle there are some large phalanges on each of the trochlea – the part where the toes articulate to – and they indicate that there would be musculature there,” she says.
“In an eagle these are quite well developed … in order to give them the strength to grab on to and pierce their talons through prey.
“In this fossil, however, the phalanges are really reduced, which indicates that this comes from a bird that doesn’t have that kind of muscular power.
“That’s consistent with what we see in other vultures today.”
The loss of vulture would have left a gap
Vultures are a bit like the garbageman of the animal world, cleaning up animal carcasses and lowering the risk of diseases spreading.
The disappearance of Cryptogyps after Australia’s Pleistocene would therefore remove an important carrion consumer from the continent’s ancient ecosystems.
This would have resulted in a major upheaval, as other organisms “scrambled to fill in its niche”.
“The extinction of vultures in Australia has major ecological implications,” says Mather. “The loss of Cryptogyps could have caused a drastic upheaval in ecosystem function for a very long time.”
Matthew Agius is a science writer for Cosmos Magazine.
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