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.
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.”
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.
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.
This 119 million year old fish, Rhacolepis, is the first fossil to show a 3D preserved heart which gives us a rare window into the early evolution of one of our body’s most important organs. Credit: Dr John Maisey, American Museum of Natural History in New York, Author provided
But certain rare fossil deposits, called konservat laggerstätten (meaning “place of storage”), are formed by rapid burial under special chemical conditions. These deposits can preserve a range of soft tissues from the organism.
The fish Rhacolepis imaged by synchrotron tomography showing the heart (left) and a cross-section through the heart showing valves (right, white arrows). Credit: Maldanis et al. (2016)
Finding a complete fossilised heart in a fish almost 120 million years old was a major breakthrough for José Xavier-Neto of the Brazilian Biosciences National Laboratory, Lara Maldanis of the University of Campinas, Vincent Fernandez of the European Synchotron Radiation Facility and colleagues from across Brazil and Sweden.