Paleontologist Matt Friedman of the University of Michigan and his colleagues accidentally made an important discovery: the remains of a 319-million-year-old brain were found in a forgotten fossil in the storerooms of the university’s museum. To date, this is the oldest brain of any vertebrate in the history of observations.
The study was published in the journal Nature and is briefly described by Phys.org. Friedman’s attention was drawn to the fossil, which was found more than a century ago and has been kept in the University of Michigan museum since 1925.
It is a fragment of a 319 million year old fossilized fish skull that was recovered from a coal mine in England. Previous studies have determined that the fossil belongs to an extinct fish, one of the progenitors of ray-finned fish.
It has been many years since he studied. However, Friedman decided to analyze the fossil using computed tomography, a technology that was simply not available to his predecessors. The scan yielded a surprising result: the CT scan revealed the remains of a fossilized brain, and also made it possible to clarify the identification of the fish. It turned out that it belongs to the species Coccocephalus wildi.
It was a very early ray-finned fish. The creature likely lived in the estuary and fed on small crustaceans, aquatic insects, and cephalopods. These fish had a backbone, so the brain found automatically became the oldest brain of all known vertebrates.
It is also surprising that parts of the brain managed to survive to the present day. Science hardly knows such examples, because the tissues of any brain are soft. They are practically not amenable to the petrification process. However, in this case, the soft tissues of the brain and cranial nerves were replaced in the petrification process by a dense mineral that retained its highly detailed three-dimensional structure.
“An important finding from the study is that the soft parts of the brain can still be preserved, so we should be looking for known fossils,” says Friedman. “This fossil, for example, has been known for more than 100 years.”
By the way, the lead author of the paper was doctoral student Rodrigo Figueroa, who completed it under Friedman’s direction. He noted that the seemingly unimpressive little fossil not only shows us the oldest example of a fossilized vertebrate brain, but also makes us look at brain evolution in a new way. Many previously recognized ideas now need to be reworked, Figueroa says.
“With the wide availability of modern imaging techniques, I wouldn’t be surprised if we found that fossil brains and other soft parts are actually much more common than we thought,” says Figueroa. “From now on, our research team and others will be studying fossil fish heads with a new perspective on them.
