Overview
- Researchers named Phascolarctos sulcomaxilliaris in a Royal Society Open Science paper published Wednesday, confirming a distinct extinct koala that lived only in Western Australia.
- The team examined 98 fossils from WA caves and museum drawers, including complete skulls donated by the family of caver Lindsay Hatcher, and found consistent differences from living koalas.
- The species shows a deep cheek groove, a shorter and more robust skull, broader teeth, and ear-region differences, which suggest larger facial muscles, different chewing, and likely lower agility in trees.
- Uranium–thorium and radiocarbon dating place the fossils between about 137,000 and 24,000 years old, with the lineage disappearing roughly 28,000–30,000 years ago as forests shrank during a cold, dry phase.
- Fossils from Yanchep, Margaret River, and the Roe Plain near Madura indicate a wide range in WA, and the authors say the find reshapes koala evolution and underscores how forest loss can erase specialized animals.