Paleontologists have re-examined the remains of extinct, large-bodied marsupials recovered from Pleistocene-aged layers of Nombe Rockshelter in the highlands of Papua New Guinea. Their findings suggest that a panda-like marsupial species still inhabited the upper montane forests around the Nombe site 55,000 years ago, and that two large, now-extinct kangaroos persisted until at least 27,000-22,000 years ago, implying at least a 30,000-year regional coexistence with humans.
Sahul — Pleistocene landmass of Australia and New Guinea — was once inhabited by a diverse array of large marsupials, reptiles and birds that became extinct during the Late Pleistocene.
Since the 19th century, many paleontologists have speculated about the putative roles of human activities and climate change in their disappearance.
Despite some improvements over the past two decades in the dating of Late Pleistocene megafaunal occurrences and human settlement, the topic of causation remains controversial.
“New Guinea is a forested, mountainous, northern part of the formerly more extensive Australian continent Sahul, but our knowledge of its faunal and human history is poor compared with that of mainland Australia,” said Professor Tim Denham, a researcher at Australian National University.
In their research, Professor Denham and his colleagues used new techniques to re-examine the large-mammal material from Nombe Rockshelter in a bid to better understand the intriguing natural history of Papua New Guinea.
The analysis produced revised ages of the bones and suggests that several large mammal species, including the extinct thylacine and a panda-like marsupial called Hulitherium tomasettii still lived in the Papua New Guinea highlands when people first arrived, possibly around 55,000 years ago.
Remarkably, two large extinct kangaroo species, including one that bounded on four legs rather than hopping on two legs, may have persisted in the region for another 30,000 years.
“If these megafaunal species did indeed survive in the Papua New Guinea highlands for much longer than their Australian equivalents, then it may have been because people only visited the Nombe area infrequently and in low numbers until after 20,000 years ago,” Professor Denham said.
“Nombe rock shelter is the only site in New Guinea known to have been occupied by people for tens of thousands of years and preserves remains of extinct megafaunal species, most of them unique to New Guinea.”
“The latest Nombe study is consistent with similar evidence from Kangaroo Island that also suggests megafaunal kangaroos may have persisted to around 20,000 years ago in some of the less accessible areas of the continent,” said Professor Gavin Prideaux, a researcher at Flinders University.
“Many general assumptions about megafaunal extinction timelines have been more harmful than helpful.”
“Although it is often assumed that all of the megafaunal species in Australia and New Guinea became extinct coast to coast by 40,000 years ago, this generalization is not based on very much actual evidence.”
“It is probably more harmful than helpful in resolving exactly what happened to the dozens of large mammals, birds and reptiles that were living on the continent when people first arrived.”
The team’s paper was published in the journal Archaeology in Oceania.
Gavin J. Prideaux et al. Re-evaluating the evidence for late-surviving megafauna at Nombe rockshelter in the New Guinea highlands. Archaeology in Oceania, published online September 16, 2022; doi: 10.1002/arco.5274
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