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.
This new genus was found in the mountains of central Papua New Guinea. But it's not closely related to its modern-day Australian descendants, as it belonged to a unique genus of more primitive kangaroos that were found only in Papua New Guinea, per the journal Transactions of the Royal Society of South Australia.
Scientists have named the animal Nombe nombe, after Nombe Rockshelter, an archaeological and palaeontological site in Papua New Guinea, where the fossil was unearthed.
The squat and muscular Nombe lived in a diverse 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.
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.