Fossilised body organs in fish

How old do you think the oldest fossilised heart is? 1 million years? 100 million? More? We found a 380 million year old fossilised heart, as well as stomach, intestine and liver in ancient jawed fishes, published today in the journal Science. (Previously the oldest known fossilised heart was described from a measly 100 million years ago…)

Finding soft tissue preserved in fossils is rare, and finding 3D preserved fossils is remarkable, so the combination of these in 380 million year old animals is mind-boggling! These fish are the ancient armoured placoderms from the famous Devonian (359-419 million years ago) Gogo reef lagerst├Ątten (meaning site of exceptional preservation) in northern Western Australia.

Gogo fish diorama at WA Museum Boola Bardip. Credit: Curtin University

Powerful imaging techniques such as synchrotron scanning by the European Synchrotron Radiation Facility in France, and neutron tomography at the Australian Nuclear and Science Technology Organisation (ANSTO) in Sydney (Australia) enabled us to see inside the specimens while they were still embedded in limestone and construct 3D models of the bones and soft tissues inside. I still remember the day sitting at ANSTO with lead author Prof. Kate Trinajstic and beam scientist Dr Joseph Bevitt looking through the latest neutron scans when we found one of the heart specimens in a placoderm called Compagopiscis.

Joseph Bevitt, Alice Clement and Kate Trinajstic at the ANSTO neutron facility in Sydney.

Importantly, the shape and position of the heart (the oldest ever found!) signifies an important step in evolution of the vertebrate body plan, and the lack of lungs suggests these organs only evolved once later on in the bony fishes.

It was so exciting to be included in this project with a kick-ass team spanning Australia, Sweden, and France with my co-authors Kate Trinajstic, John Long, Sophie Sanchez, Catherine Boisvert, Daniel Snitting, Paul Tafforeau, Vincent Dupret, Peter Currie, Brett Roelofs, Joseph Bevitt, Mike Lee and Per Ahlberg.

These Gogo fossils just keep on giving! If you would like to learn more, you can read an article by Kate and John in The Conversation or this one from Cosmos Magazine (complete with a few extra dorky pics of me “science-ing”.