Australian Aborigines Probably Ate Some Species of Birds into Extinction

Genyornis newtoni, a 500 pound flightless bird related to geese and ducks, roamed Australia during the Pleistocene.  Most scientists believe genyornis primarily ate plants, like its cousins; but a minority think it was carnivorous.  Supposed egg shells of this extinct bird occur frequently in the fossil record along with eggshells of the still extant emu (Dromaus novachellandiae) until between 50,000-45,000 years ago.  This is the time period when people first colonized the Australian continent.  A group of scientists examined 700 eggshells from 500 sites and determined that human exploitation of genyornis eggs led to its extinction between 53,000 BP-44,000 BP.  Many of the eggs were apparently cooked in embers–direct evidence humans were eating the eggs.  After this time period humans continued to eat emu eggs, but genyornis eggshells no longer occur in the archaeological record.  Emus were more resilient to human exploitation than the slower breeding, larger species.

However, a recent study casts doubt on the identification of the genyornis eggs.  The scientists who authored this paper suggest the alleged genyornis eggs are far too small to have been laid by a bird the size of genyornis.  These eggs are slightly smaller than emu eggs, and emus are much smaller than genyornis was.  They suggest the eggs thought to be from genyornis belonged to another extinct species, a bird in the progura genus that is related to the Australian brush turkey and the mallee bird.  This extinct species likely reached just 12 pounds.  They believe the data from the first study mentioned above strongly suggests man is responsible for the extinction of the progura species but does not explain how genyornis became extinct.  If this second study correctly identified the bird genus in question, than there are no known specimens of genyornis eggs.  The emu and progura eggshell fragments were found in arid sand dunes.  Genyornis probably lived in wetter more wooded environments where their egg shells didn’t survive the ravages of time.

Ancient%2Bextinction%2Bof%2Bgiant-Geolog

Illustration of megalania hunting a large (also extinct) bird known as Genyornis newtoni.  Humans probably overexploited them into extinction, but the evidence that aborigines cooked and ate their eggs may be a case of misidentified eggshells.

A red ochre painting, which depicts two emu-like birds with their necks outstretched

Archaeologists believe this Australian cave painting is of a Genyornis newtoni.  Paintings of other extinct Australian megafauna have been found in the same region.  It is estimated to be at least 40,000 years old.

The purported genyornis egg on the left has probably been misidentified.  Note how small it is compared to the genyornis leg.  Instead, eggs identified as being laid by Genyornis newtoni were probably laid by a species in the Progura genus.

Leipoa ocellata -Ongerup, Western Australia, Australia-8.jpg

A new study suggest the eggs belonged to an extinct genus related to this species–Leipoa ocellata, the mallee bird.

A recent statistical study does implicate overhunting by man as the reason for the extinction of Australia’s megafauna.  The authors of this study determined climate change could not have caused the extinctions.  Proponents for climate change models of extinction in Australia claim increasing aridity eliminated habitat for many species of megafauna including megalania, a land crocodile, a giant kangaroo, a giant echidna, a marsupial lion, and genyornis.  However, these extinctions took place during Marine Isotope Stage 3 (60,000 years BP-30,000 years BP), a climate stage that was less arid than the previous MIS 4.  All of these species survived the greater aridity of MIS 4 and its harsher condition but became extinct after man arrived on the continent.  The megafauna extinctions took place within less than 13,500 years after man’s arrival on the continent, supporting a protracted overkill scenario.  The authors concede that overhunting by man for some species in some regions may have resulted in a more rapid extinction in some cases, but overall it took millennia for aborigines to wipe out most of Australia’s megafauna.

References:

Miller, Gifford; et. al.

“Human Predation Contributed to the Extinction of the Australian Megafaunal Bird Genyornis newtoni”

Nature Communications 2016

Grellel-Tinner, Gerald; Nigel Spooner, and Trevor Worthy

“Is the “Genyornis” Egg of a Nihirung or Another Extinct Bird from the Australian Dreamtime?”

Quaternary Science Reviews 2016

Saltre, Frederick; et. al.

“Climate Change not to Blame for Late Quaternary Megafauna Extinctions in Australia”

Nature Communications 2016

 

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