Fossil molars offer insight into kangaroo ancestors
UPPSALA, Sweden: Kangaroos are icons of Australia’s unique living fauna whose earliest ancestry has yet to be discovered. However, using archaeological findings that were unveiled in Australia 30 years ago, researchers from Uppsala University recently identified the most distant ancestor of today’s kangaroos with the help of new technology.
In the early 1980s, palaeontologists excavated a few enigmatic molars around a dry salt lake in northern South Australia. The rare specimens were recognised as belonging to an ancient kangaroo ancestor and stored in a museum collection for more than three decades until modern computer-based analysis enabled researchers to confirm the significance of the discovery. The kangaroo ancestor was named Palaeopotorous priscus, which is Latin for “ancient rat-kangaroo”.
“Our results showed that Palaeopotorous was most similar to living rat-kangaroos, as well as some other extinct kangaroo relatives. Using information from fossils, and the DNA of living species, we were able to further determine that at around 24 million years old, Palaeopotorous is not just primitive, but likely represents the most distant forerunner of all known kangaroos, rat-kangaroos and their more ancient ancestors,” said lead author Dr Wendy den Boer, recent doctoral student at the university and current staff member of the Swedish Museum of Natural History.
“Palaeopotorous was about the size of a small rabbit, and probably did not hop, but would have bounded on all four legs. Nevertheless, a few bones found at the same site in central Australia indicate that the earliest kangaroos already possessed some key adaptations for hopping gaits,” said co-author Dr Benjamin Kear from the Museum of Evolution at the university.
Palaeopotorous lived at a time when central Australia was much wetter than it is today. Its fossils were buried in clay deposits left by a river, even though these earliest kangaroo ancestors would have foraged among vegetation growing nearby and along the banks. The teeth of Palaeopotorous were washed into the river after their death, along with the remains of many other ancient marsupials.
The study, titled “Is the fossil rat-kangaroo Palaeopotorous priscus the most basally branching stem macropodiform?”, was recently published in the Journal of Vertebrate Paleontology (Volume 38, Issue 2).
Tags: fossil, kangaroo ancestor, molar teeth, Sweden