New research based on CT scans of a 400 million year old fish fossil has discovered a jaw structure that forms part of the evolutionary link to human.
The Australian National University research, published in Scientific Reports this week, used new CT scans and 3D printing technology to uncover the link.
Scanning the fossil found in the ancient limestones near Lake Burrinjuck, and then making 3D print outs of the fishes jaw structure, revealed an upper jaw bone strikingly similar to that found in humans.
ANU PhD student Yuzhi Hu said the fossil was the best preserved skull and braincase of a placoderm ever found.
Ms Hu said the research has shown the jaw joint found in the fish skull was "still in the human skull", but now formed one of the small bones in humans' inner ear.
Once regarded as a side-branch of research on evolution, the recent discovery of Chinese maxillate placoderms has brought them into the scientific spotlight.
Co-author of the ANU paper, Dr Jing Lu, was part of the team in Beijing that made that discovery before she came to Canberra.
Dr Lu said the maxilla was the bone that formed the upper jaw in humans, and the Chinese fish fossils discovered had the same bone, demonstrating a much closer relationship to human ancestry than previously thought.
"But other internal structures were apparently made of cartilage, and are not clearly preserved, unlike the Burrinjuck skull," she said.
Dr Lu said very few fossils preserved such intricate details to allow the reconstruction of extinct animals.
"The Australian fossil helps us to interpret these aspects in the Chinese maxillate placoderms," she said.
"Thanks to the international collaboration, we are making great progress to work out the sequence of key evolutionary innovations at the origin of the jawed vertebrates."