Australasian Science Magazine

An ancient bilby fossil discovered at the Riversleigh World Heritage site in north-west Queensland has pushed back the date when these endangered marsupials first evolved.

Until now, the oldest bilby fossil was only about five million years old, but the discovery of a 15-million-year-old fossil by palaeontologists from The University of Queensland and the University of NSW confirms that bilbies evolved millions of years earlier than was previously known.

DNA studies on related species had predicted that the bilby had evolved about 25 million years ago, when it separated from its closest relative, the bandicoot. “The species that we have discovered is about 15 million years old, which is more in accordance with the DNA data and will provide insight on how bilbies have evolved over time and adapted to changes in the Australian environment,” said lead researcher Dr Kenny Travouillon of UQ’s School of Earth Sciences.

The species has been named Liyamayi dayi, which is derived from the Aboriginal Waanyi people’s language and means “day’s round tooth”. The “day” refers to UQ alumnus and geologist Dr Robert Day, who funded Travouillon’s postdoctoral fellowship.

Travouillon and his team also recovered fossils of a 15-million-year-old species related to modern bandicoots from the same area. “Just like the bilbies, the previously oldest known ancestor of the modern bandicoots was also about five million years old, and hence this finding also pushes back their age,” Travouillon said.

As the new bandicoot species was found in an unusual time period – almost crashing in a time period where it was least expected – the team has named it Crash bandicoot after a video game character.

The fossils were discovered several years ago, and the results of subsequent research have now been published in the Journal of Vertebrate Paleontology.