Two tiny bones have lead to a large revelation about the origin of some of Australia’s marsupials.

The discovery and identification of an ankle bone and a tooth are prompting an overhaul of theories about marsupial evolution, after they revealed unexpected links to South America and possibly Africa.

The bones were found at Tingamarra in south-eastern Queensland; one has been confirmed as a 55 million-year-old ankle bone from a mouse-sized marsupial previously known only in South America. The tooth appears to derive from a formerly unknown species, which shows similarities to fossils found in South America and, oddly, North Africa.

The two fragments could turn current theories of the evolution of native marsupials on their heads. Conventional thinking has until now said there was a single migration from the part of the Gondwana 'supercontinent' that became South America to the part that became Australia, this origin story now appears far more complicated.

Paleontologists at the University of New South Wales are working to ascertain the exact origin of the two bone fragments, Dr Robin Beck, an ARC DECRA postdoctoral fellow says: “It is impossible to explain the presence of these new fossils in Australia using the single dispersal model. Instead, there may have been multiple movements of marsupials between South America and Australia... all the species of modern day marsupials here are quite closely related. The species represented by the ankle-bone belongs to an entirely different group - a group that we know lived in South America but, up until now, we thought never made it to Australia.”

Dr Beck said the find reminded him of a fellow scientist, saying he, "named it after one of my colleagues, Henk Godthelp, who has led research at Tingamarra together with Mike Archer and Sue Hand... Henk's nickname is 'The Old Bastard', so I've called the species Archaeonothos henkgodthelpi, which translates, roughly, to 'the ancient illegitimate of Henk Godthelp'. The name also implies the species is unrelated to other Australian marsupials."

Research will continue, and likely result in new ideas about waves of migration to the Australian continent.

Dr Beck is one of 12 early-career scientists unveiling their research to the public for the first time thanks to Fresh Science, a national program sponsored by the Australian Government through the Inspiring Australia initiative.