A team of researchers from Curtin University in Perth, Australia, has discovered the fossilized heart, stomach, intestine and liver of an armored fish in Australia. The incredible discovery of the heart of this fish, 380 million years old, places it in the oldest ever found and provides us with new data on the evolution of our own body.
The position of the organs is similar to the modern anatomy of the shark, say the experts, who have published their study in the journal Science.
Discovered in the Gogo Formation, the remains of an ancient reef system in northwestern Australia, the fossil captured the ancient fish’s heart, stomach, intestines and liver. The most amazing thing about the discovery is that the organs are preserved in their original positions in three dimensions , instead of having been crushed by rocks over millions of years, as is often the case.
It’s quite a milestone, because the soft tissues of organisms don’t fossilize well, so most of the time scientists have to infer the anatomy of organs from bones alone. This fossil treasure has been unexpected (and if it is already difficult to find soft tissues, it is even rarer to find three-dimensional soft tissues).
What kind of fish is it?
The fossil belongs to a species of arthrodire, a group of armored fish that dominated the oceans during the Devonian period between 420 and 360 million years ago. They were among the first vertebrates to develop jaws, which represented a fairly important innovation in evolution. Regarding the organs… it’s another story; something much more difficult to track, until this Gobo fish has appeared.
Thanks to its amazing state of preservation, details such as an atrium, a ventricle and an outflow tract can be clearly identified in the fossil. The heart was shaped like a compound S and was made up of two chambers, with the smaller chamber above the larger one.
“As a paleontologist who has studied fossils for over 20 years, I was very surprised to find a very well-preserved 3D heart in a 380-million-year-old ancestor. Evolution is often thought of as a series of baby steps, but these ancient “Fossils suggest there was a larger gap between jawless and jawed vertebrates. These fish literally have their hearts in their mouths and under their gills, just like sharks today,” said co-author Kate Trinajstic.
Primitive jawed fish aren’t that different from us
Trinajstic showed that these features developed in these early vertebrates, offering a unique window into how the head and neck region began to change to accommodate jaws, a critical stage in the evolution of our own bodies.
“For the first time, we can see all the organs together in a primitive jawed fish, and we were especially surprised to learn that they weren’t that different from us,” Trinajstic said. “However, there was a critical difference: The liver was large and allowed the fish to remain buoyant, just like today’s sharks. Some of today’s bony fish, such as lungfish and birchfish, have lungs. that evolved from swim bladders, but it was significant that he found no evidence of lungs in any of the extinct armored fishes we examined, suggesting that they evolved independently in bony fishes at a later date .”
The researchers hope the finding will help shed light on the evolution of the human body.
“Gogo has given us world firsts , from the origins of sex to the oldest vertebrate heart, and is now one of the world’s most important fossil beds. It’s time the site was seriously considered for World Heritage status.” “, the authors conclude.
Referencia: Kate Trinajstic, John A. Long, Sophie Sanchez, Catherine A. Boisvert, Daniel Snitting, Paul Tafforeau, Vincent Dupret, Alice M. Clement, Peter D. Currie, Brett Roelofs, Joseph J. Bevitt, Michael S. Y. Lee, Per E. Ahlberg. Exceptional preservation of organs in Devonian placoderms from the Gogo lagerstätte. Science, 2022; 377 (6612): 1311 DOI: 10.1126/science.abf3289
