A giant fossil of the ancestor of modern-day Australian kangaroos that went extinct around 42,000 years ago has been discovered by paleontologists in a finding that sheds more light on the evolution of the marsupials.
The new genus of the giant fossil kangaroo was found from the mountains of central Papua New Guinea.
The last species in the genus was a cousin of modern-day eastern grey and red kangaroos in Australia, said researchers, including those from Flinders University.
But rather than being closely related to its modern-day Australian descendants, it belonged to a unique genus of more primitive kangaroos that were found only in Papua New Guinea, said the findings described in the journal Transactions of the Royal Society of South Australia.
Scientists have renamed the animal Nombe nombe, after Nombe Rockshelter, an archaeological and palaeontological site in Papua New Guinea’s Chimbu Province, where the fossil was discovered.
The squat and muscular Nombe lived in a diverse montane rainforest with thick undergrowth and a closed canopy where it adapted and evolved to eat tough leaves from trees and shrubs using its thick jaw bone and strong chewing muscles.
“The New Guinean fauna is fascinating, but very few Australians have much of an idea of what’s actually there,” Isaac Kerr, a palaeontology PhD candidate from Flinders, said in a statement.
“There are several species of large, long-nosed, worm-eating echidna that are still around today, many different wallaby and possum species that we don’t get in Australia, and more still in the fossil record,” he explained.
Based on the study, scientists suspect many species may have evolved from an ancient form of kangaroo located in New Guinea in the late Miocene epoch about 5 to 8 million years ago.
The islands of New Guinea and mainland Australia were connected by a ”land-bridge” at the time due to lower sea levels, as opposed to currently being separated by the flooded Torres Strait.
This bridge allowed early Australian mammals, including various giant, extinct ones, to move into the rainforests of New Guinea, said scientists.
When the Torres Strait flooded again, however, these populations of animals became disconnected from their Australian relatives and evolved separately to suit their new tropical, mountainous home.
“We’re very excited to undertake three palaeontological digs at two different sites in eastern and central PNG [Papua New Guinea] over the next three years,” said Gavin Prideaux, Flinders University professor and study co-author.
“We’ll be working with the curators of the Papua New Guinea Museum and Art Gallery and other contacts in PNG, with whom we hope to build some local interest in New Guinean palaeontology,” Dr Prideaux added.
