Scientists have discovered the world’s oldest heart in a 380 million-year-old fossil of a jawed fish.
Researchers from Curtin University in Australia found the “beautifully preserved” heart alongside a separate fossilised stomach, intestine and liver, with the organs’ position resembling that of a shark’s anatomy.
The hope is that the invention could make clear how creatures, including humans, evolved.
The muscular organ comes from a fossilised jawed fish that swam within the waters through the Devonian period, between 419 million and 359 million years ago.
In line with the scientists, the findings, published within the journal Science, suggest the organs come from the body of a fish from the arthrodire family – an extinct group of armoured fishes which have anatomies just like a contemporary shark.
The interior organs of an ancient armored fish are seen on this undated artist’s reconstruction
Lead researcher Professor Kate Trinajstic described their finding as “remarkable” as it is vitally rare to seek out soft tissues of ancient species so well preserved.
Prof Trinajstic said: “As a palaeontologist who has studied fossils for greater than 20 years, I used to be truly amazed to seek out a 3D and beautifully preserved heart in a 380-million-year-old ancestor.
“Evolution is commonly regarded as a series of small steps, but these ancient fossils suggest there was a bigger leap between jawless and jawed vertebrates.
“These fish literally have their hearts of their mouths and under their gills – similar to sharks today.”
The researchers found the fossils within the Gogo Formation within the Kimberley region of western Australia, a reef which preserves unique fauna and flora from the late Devonian period.
Based on on the discoveries, the researchers created 3D models of of the jawed fish, which showed the center was made up of two chambers, with the smaller one sitting on top.
Professor Kate Trinajstic from Curtin University’s School of Molecular and Life Sciences inspects fish fossils
Prof Trinajstic said their findings offer a “unique window” into how the pinnacle and neck region began to evolve to accommodate jaws.
She said: “For the primary time, we are able to see all of the organs together in a primitive jawed fish and we were especially surprised to learn that they weren’t so different from us.
“Nevertheless, there was one critical difference – the liver was large and enabled the fish to stay buoyant, similar to sharks today.
“A few of today’s bony fish akin to lungfish and birchers have lungs that evolved from swim bladders nevertheless it was significant that we found no evidence of lungs in any of the extinct armoured fishes we examined, which suggests that they evolved independently within the bony fishes at a later date.”
Professor John Long, from Flinders University, who was a co-author of the study described teh discovery as “truly the stuff of a palaeontologist’s dreams”.
He added: “Gogo has given us world firsts, from the origins of sex to the oldest vertebrate heart, and is now probably the most significant fossil sites on the earth.
“It’s time the location was seriously considered for world heritage status.”
Additional reporting by PA