A 380-million-year-old fish heart found embedded in a chunk of Australian sediment has scientists’ pulses racing. Not only is this organ in remarkable condition, it could also hold clues to the evolution of jawed vertebrates, including you and me.
The heart belonged to an extinct class of armored, jawed fish called arthrodires that thrived in the Devonian period between 419.2 million and 358.9 million years ago, and the ticker is a good 250 million years older than the heart of the jawed fish which currently contains the “oldest title”. But as archaic as the fish is, the position of its two-chambered, S-shaped heart led researchers to observe striking anatomical similarities between the ancient swimmer and modern sharks.
“Evolution is often thought of as a series of small steps, but these ancient fossils suggest there was a bigger jump between jawless and jawed vertebrates,” said Professor Kate Trinajstic, a vertebrate palaeontologist at Australia’s Curtin University. and co-author of a new study. about the findings. “These fish literally have their hearts in their mouths and under their gills, just like sharks today,” Trinajstic said.
The study showed up in the journal Science on Wednesday.
Scientists got a good look at the exact location of the organ because they were able to see it in relation to the fish’s fossilized stomach, intestine, and liver, a rare occurrence.
“I can’t tell you how truly amazed I was to find a beautifully preserved 3D heart and other organs in this ancient fossil,” said Trinajstic.
The white ring shows the spiral valves of the intestine, but the heart is not seen here. “I was totally blown away by the fact that we were able to see preserved soft tissue in such an ancient fish,” says John Long, professor of palaeontology at Flinders University in Australia and co-author of a new study on the find. “I knew right away that this was a very significant find.”
John Long/Flinders University
Paleontologists found the fossil during a 2008 expedition in the GoGo Formation, and it adds to a wealth of information gleaned from the site, including the origins of the teeth and insights into the transition from fin to limb. The GoGo Formation, a sedimentary deposit in the Kimberley region of Western Australia, is known for its rich fossil record that preserves reef life from the Devonian period of the Paleozoic era, including relics of such delicate tissues as nerves and bones. embryos with umbilical cords.
Anatomy of an arthrodire.
“Most cases of soft tissue preservation are found in flattened fossils, where the soft anatomy is little more than a speck in the rock,” said study co-author Professor Per Ahlberg of Uppsala University in Sweden. “We are also very lucky because modern scanning techniques allow us to study these fragile soft tissues without destroying them. A couple of decades ago, the project would have been impossible.”
Those techniques include neutron beams and X-ray microtomography, which creates cross-sections of physical objects that can then be used to recreate virtual 3D models.
Recent finds of fish fossils have illuminated how critically endangered ‘dinosaur fish’ stand on their heads and how much the prehistoric fish lizard he looked like flipper the dolphin.
But for those who might not find such discoveries significant, study co-author Ahlberg has a reminder: that life is, at its most fundamental level, an evolving system.
“That we ourselves and all other living organisms with whom we share the planet have developed from a common ancestor through a process of evolution is not an incidental fact,” Ahlberg said. “It is the deepest truth of our existence. We are all related, in the most literal sense.”
