Researchers find world’s oldest fossilised heart in Fitzroy Crossing

A team of scientists working on a remote cattle station in the Kimberley has discovered the world’s oldest vertebrate fossilised heart, inadvertently providing the missing link in the story of human evolution.

Curtin Molecular and Life Sciences professor and palaeontologist Kate Trinajstic was leading a dig at Gogo Station, 11km south of Fitzroy Crossing, when a colleague unearthed a compelling rock.

“When we first found the rock, we cracked it open and saw a series of concentric rings which immediately told us we had part of the intestine,” she said.

The intestine belonged to a 380 million-year-old placoderm, a prehistoric class of fish and one of the homosapien’s earliest jawed ancestors.

The creature is more commonly known as the Gogo Fish, the most abundant fish of the Devonian Period of 419-359 million years ago.

For Professor Trinajstic, the discovery of the intestines was enough to employ high-tech equipment to reveal the rest of the rock’s contents.

“We used two types of imaging,” she said.

“The first one we did was the synchrotron — basically a big particle accelerator in France, about the size of a football field, which fires off electrons and speeds them up to the speed of light. It acts like a CT scanner of a much higher power.”

“The other scan we used was a neutron scanner, which used neutrons to enable us to look inside the rock.”

It was during this process the team of researchers — hailing from Curtin, Monash and Flinders universities — realised the true significance of their discovery.

“We thought we could get lucky and get a full intestine and maybe some more pieces of muscle,” Professor Trinajstic said.

“But what we got was a full complement of organs — the internal organs of a 380 million-year-old fish — which was just astounding,” she said.

“We’ve been hunting for the holy grail of fossils, which is soft tissue preservation, and we discovered it — a full set of organs.”

Among the organs was the oldest three-dimensionally preserved heart from a vertebrate — approximately 380 million years old, 250 million years older than the previous oldest vertebrate heart.

More so, the discovery provided concrete evidence that the placement of the heart and structure of the neck were linked to the evolution of the jaw.

“We know that these fish have a specialised neck, we know they have a jaw, and we know that they had a heart in the back of their throat,” Professor Trinajstic said.

“There’s been a theory that, in the evolution of jaws, these three things are linked and this was the first evidence that shows that this was true.”

Professor Trinajstic said the discovery was incredibly significant to human evolution.

“We’re looking at an animal that was basically at the start of our evolutionary journey,” she said.

“A discovery like this means you stop guessing. You can actually see what the internal structures are like — this is incredibly rare in the fossil records.”

Now Professor Trinajstic is pushing for more areas in the Kimberley to gain World Heritage Status in the name of preservation.

“It’s a wonderful place in the world,” she said. “There’s lots to discover up there. Not just fossil sites, but native sites as well. It’s about making sure these areas are there for the future.”