There Was No Record of Koalas Here. Until Now

The modern koala is a well-known and well-loved marsupial, but researchers know surprisingly little about its evolution. Indeed, they describe an "approximately 30-million-year-gap" in the fossil record of Australian marsupials, or diprotodontians, a group including kangaroos, wallabies, and wombats. That gap may be closing, however. Researchers say they've discovered fossils from an unknown "member of the koala family (Phascolarctidae) or a close relative" at the Pwerte Marnte Marnte site in Australia's Northern Territory that may provide a missing link in the evolutionary chain. The new species, dubbed Lumakoala blackae, would've been about the size of a small house cat, roughly 6 pounds at maximum, and possibly quite cute, the New York Times reports.

Fossilized teeth from the leaf-eating Lumakoala, dated at 25 million years old, show key similarities to teeth from two species of small marsupials, Chulpasia jimthorselli and Thylacotinga bartholomaii, which roamed northeastern Australia 55 million years ago. It was thought that Chulpasia and Thylacotinga were related to marsupials from South America, which was once connected to Australia as part of the supercontinent Gondwana. "However, the discovery of Lumakoala suggests that Thylacotinga and Chulpasia could actually be early relatives of Australian herbivorous marsupials such as koalas, wombats, kangaroos, and possums," says Flinders University PhD student Arthur Crichton, lead author of a study on the find published this month in Scientific Reports.

"If our hypothesis is correct, it would extend the diprotodontian fossil record back by 30 million years," says Crichton. Fossils indicate two previously known species of koala, Madakoala and Nimiokoala, lived alongside Lumakoala in the Northern Territory, per CTV News. "Until now, there's been no record of koalas ever being in the Northern Territory," notes study co-author Gavin Prideaux, a Flinders University paleontologist. He adds there were at least seven koala species during the late Oligocene Epoch (23–25 million years ago), which was "kind of the koala heyday." There were also giant koala-like marsupials called ilariids, which the Times reports would've been "rather terrifying ... with an estimated weight of as much as 440 pounds, roughly the size of an upright piano." (More koala stories.)