Scientists have discovered the world’s oldest heart in a 380 million-year-old fossilized fish

Paleontologists have identified a mineralized core inside a 380 million-year-old fossilized fish. It is an extremely rare finding, as soft tissues tend to decompose before ossification occurs. He is getting better. Surveying the fossil allowed researchers to study its anatomy in 3D without having to break the exact fossil.

Image credit: researchers.

The heart of the ancient fish was an S-shaped organ with two chambers – the smaller one sitting above the larger chamber. The researchers explained that it was much more advanced than paleontologists had expected and could provide valuable information about the evolution of the head and neck region, and how it changed to fit the jaws.

“Evolution is often thought of as a series of small steps, but these ancient fossils suggest there was a greater leap between jawless and jawless vertebrates. These fish literally carry their hearts out,” said Kate Triangstick, study author from Curtin University in Australia, in a statement. In their mouths and under their gills – just like today’s sharks.

looking at the heart

The heart belongs to a fish known as juju that has now been extinct for a long time. It is the first of the prehistoric fish category are called placoderms The first fish with jaws and teeth. Placoderms can be up to nine meters long and have been the dominant life on the planet for 60 million years, appearing more than 100 million years before the appearance of the first dinosaurs.

It was found on a site known as jojo formation in Western Australia. During the Devonian period, between 419 million years ago and 358 million years ago, this area was a large coral reef thriving with life. But things have changed since then. It is now such an exceptional fossil bed that sometimes soft tissues can be found in very good condition.

Image credit: researchers.

“The really exceptional thing about the gogo fish is that its soft tissues are preserved in three dimensions,” Per Ahlberg, study author and researcher at Uppsala University in Sweden, said in a statement. “Most cases of soft tissue preservation are found in flattened fossils, where the soft anatomy is little more than a speck on the rock.”

The two chambers made the fish’s core more efficient, the researchers said, and were a key step in turning it from a slow-moving fish into a fast predator. The heart was also much more advanced in body than the heart of more primitive fish. They argued that this was related to the evolution of the juju’s neck.

Also interesting, the researchers said, was what wasn’t there: the lungs. Fish were the first animals to develop lungs and some still use them to breathe air. Others have reused their lungs as swimming bladders. There was no sign of lungs in the fossils, suggesting that the evolution of these organs occurred in bony fish after they diverged from the dermal plaques.

Zerina Johansson of the Museum of Natural History, a world leader in skin, was not involved in the study. He told the BBC The research is a “very important discovery”. She explained that there are many things in skin evolution that we can see in living things today – including humans – such as the neck and the shape, arrangement and location of the heart.

The study was published in Science Journal.