The heart of a 380 million-year-old fish has been found inside a piece of Australian sediment, sending scientists’ heartbeats up. Not only is this organ in great shape, but it can also provide clues about the evolution of jawed vertebrates, which includes you and me.
The heart belongs to an extinct class of armored fish with jaws called arthropods that flourished in the Devonian period between 419.2 million and 358.9 million years ago – and the heart is 250 million years older than the jawed fish core that currently bears the “oldest”. But even though the fish is very old, the placement of its S-shaped heart with two chambers has led researchers to note the surprising anatomical similarities between ancient swimmers and modern sharks.
Professor Kate Triangstick, a vertebrate paleontologist at Curtin University in Australia and co-author of a new study on the findings said. “These fish literally have their hearts in their mouths and under their gills – just like today’s sharks,” Triangstick said.
The study was published in the journal Science on Wednesday.
The scientists took an extra close look at the exact location of the organ because they were able to observe it in relation to the fossilized fish’s stomach, intestines and liver, which are rare.
“I can’t tell you how surprised I was to find a beautifully preserved 3D heart and other organs in this ancient fossil,” Trinagistic said.
The fossils were discovered by paleontologists during a 2008 expedition at GoGo Formation, and they add to a body of information gleaned from the site, including the origins of the teeth and insights about the transition from fins to limbs. The GoGo Formation, a sedimentary deposit in the Kimberley region of Western Australia, is known for its rich fossil record sustaining Devonian reef life from the Paleozoic Era, including the remains of delicate tissues such as nerves and embryos with umbilical cords.
“Most cases of soft-tissue preservation are found in flattened fossils, where the soft anatomy is little more than a speck on the rock,” said study co-author, Per Ahlberg of Sweden’s Uppsala University. “We are also very fortunate that modern scanning techniques allow us to study these fragile soft tissues without destroying them. Two decades ago, the project would have been impossible.”
These techniques include neutron beams and X-ray microimaging, which create cross-sections of physical objects that can then be used to recreate virtual 3D models.
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But for those who might not consider such discoveries significant, study co-author Ahlberg has a reminder: that life is, at its most basic level, an evolving system.
“The fact that we ourselves and all other organisms with whom we share the planet evolved from a common descent through a process of evolution is not an accidental fact,” Ahlberg said. “It is the most profound truth of our existence. We are all connected, in the most literal sense.”
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