Paleontologists recently discovered a 380-million-year-old heart preserved inside a fossilized prehistoric fish.
The researchers say the specimen captured a key moment in the evolution of the blood-pumping organ found in all back-boned animals, including humans. The heart belonged to a fish known as the Gogo, a prehistoric fish that is now extinct.
The discovery was recently published in the journal Science and was made in Western Australia. Professor Kate Trinajstic, the lead scientist from Curtin University in Perth, Australia, told BBC News about the time when she and her team realized that they had made an unexpected biggest discovery of their lives.
Trinajstic remembered how their team was crowded around the computer and recognized that "they had a heart" and pretty much couldn't believe it. She uttered that "It was incredibly exciting.
How The Oldest Heart Preserved
The team explained how usually the bones rather than the soft tissues are turned into fossils. The Gogo rock formation minerals have preserved much of the fish's internal organs, including its stomach, liver, intestine, and the oldest 3D heart.
Trinajstic added that it was a crucial moment in evolution, for the body plan was different in the early centuries compared to the present time because of evolution.
She collaborated with Adelaide's Flinders University professor John Long. The scientists described the findings as "mind-boggling, jaw-dropping discovery."
Professor Long said that they had never known anything about the soft internal organs of animals until this latest discovery.
The oldest heart found in the Gogo fish.
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Evolution of Gogo Fish's Heart
The Gogo fish is the first of a class of prehistoric fish that is defined as placoderms. These were the first fish to have physical traits like jaws and teeth. Before the Gogo, fishes were no bigger than 30 centimeters, but the placoderms could grow up to 29.5 feet (9 meters) long.
The placoderms were the earth's dominant life form for 60 million years, existing for more than 100 million years before the first dinosaurs walked on the planet.
The scans of the Gogo fish fragments showed that its heart was more complex than expected for these primitive fish. The Gogo has two chambers, one on top of the other, similar in structure to the human heart.
The scientists suggest this made the fish's heart more efficient and became a critical step that transformed it from a slow-moving fish to a fast-paced predator.
Long said that this was the way the Gogo could up the ante and become a voracious predator.
Some other important observation was that the heart was much more forward in the body than those of most primitive fish. The position is believed to have been related to the development of the Gogo fish's neck and made space for the development of the lungs, and gave further down the evolutionary line.
The Natural History Museum, London Doctor Zerina Johanson, a world leader in placoderms and an independent of Trinajstic's team, described the study as an "extremely important discovery" that explains why the human body is the way it is in the present time.
It was agreed in the statement of Doctor Martin Brazeau, a placoderm expert from the Imperial College London.
"It's really exciting to see these results," Brazeau told BBC News.
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