A primitive kangaroo has been classified as a new species, after reanalysis of fossil jaws and teeth found in the remote highlands of Papua New Guinea in the 1970s.
Most important points:
- The kangaroo is thought to be of a new genus that migrated to New Guinea between 5 and 8 million years ago
- The fossil was originally discovered in the 1970s during an expedition that led mine Mary-Jane Mountain to Simbu Province
- Researchers will return to PNG to search for more intact fossil specimens
The extinct The animal is believed to have been a rainforest browser, descended from a primitive lineage that migrated from Australia to New Guinea between 5 and 8 million years ago.
This is evident from the results of a study published today in Transactions of the Royal Society of South Australia†
the fossils were originally discovered during an expedition led by archaeologist Mary-Jane Mountain in the 1970s.
Then in 1983 — by then-paleontologist and PhD student Tim Flannery — they were classified as belonging to a species in the genus protemnodon†
protemnodon is a genus of extinct megafauna that lived in Australia and New Guinea.
The last species in the genus is thought to have become extinct in Australia about 42,000 years ago and was a cousin of today’s eastern gray and red kangaroos.
But researchers at Flinders University reclassified the PNG fossils as belonging to a new genus of kangaroo, after analyzing 3D scans, they took the jawbones and teeth, which are in the National Museum and Art Gallery of Papua New Guinea.
Based on some very unique features of the teeth and jaw, the researchers propose that the kangaroo is now known as: nombe nombe — after the Nombe rock shelter in PNG’s Simbu province, where it was found, according to the study’s lead author, PhD candidate Isaac Kerr of Flinders University.
“In the case of the Nombe, they have these funny curved lophids or combs on their molars, which show that they were doing something very different from what the protemnodon were doing,” said Mr Kerr.
“There were [features] You don’t get that in the more derivative kangaroos like the gray and the red.”
Kangaroos originated in Australia and are thought to have moved to New Guinea when the landmasses periodically merged into what is now the Torres Strait, according to Mark Eldridge, the Australian Museum’s group manager of terrestrial vertebrates.
“The radiation center for kangaroos is Australia, the oldest fossils are all from Australia and the greatest diversity of kangaroos is still in Australia,” said Dr. Eldridge, who was not involved in the investigation.
“As the continent drifted north and New Guinea was pushed up as a landmass, much of Australia’s fauna spread to New Guinea.”
So what did? nombe nombe looks like?
Often it’s just fragments of skeletons that taxonomists have to work with when trying to figure out a species’ identity, said Dr. Eldridge.
“In paleontology, jaws and teeth in particular are very robust and don’t break easily, so they’re often what survives.”
The most recent fossils of nombe nombe discovered so far show it may have existed in the highlands of New Guinea until at least 20,000 years ago.
With only a partial skeleton to go on, what it looked like is still up for debate, but there are some things the researchers are pretty sure about, according to Mr. Kerr.
“It probably jumped, but not very efficiently,” he said.
The species is estimated to have grown to between 40 and 50 kilograms.
The researchers also tried to place the animal on the phylogenetic kangaroo tree, Kerr said.
“We also did the first [analysis] of its evolution, showing that it is a much more primitive kangaroo — an older lineage that has in common with more basal kangaroos,” he said.
“We found that it has no modern close relatives because it evolved so long ago.”
Paleontologist Gilbert Price of the University of Queensland said it was important to remember that taxonomic classification was always a hypothesis and there was always room for testing and refinement.
†protemnodon [has] about nine or ten species, [but] they actually only compared [the Nombe nombe jaw bone] to one species in that group when they did the full pedigree analysis,” said Dr. Price.
“Ideally, if you’re going to say this thing is no longer part of that group, you’d probably want to expand that analysis.”
However, he commended the authors for publishing the hypothesis so that it can be debated.
“That’s the thing with taxonomy — they’re literally hypotheses and hypotheses are testable; you can test them through further research.
And the authors themselves plan to test their hypothesis by returning to Papua New Guinea to look for more intact samples, Kerr said.
“We’ll be going to New Guinea once a year for the next three years,” he said.
“One of the sites we’re digging is from a late Pleistocene site, and we hope to get more of the species there.”
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