A 319-million-year-old fossilized fish pulled from a British coal mine more than a century ago has revealed the oldest example of a well-preserved vertebrate brain, researchers say.
Scans revealed that the creature’s skull contained a brain and nerves about an inch long behind the brain.
Scientists at the University of Birmingham and the University of Michigan (USA) believe the discovery opens a window into the organization of the brain and nervous system, and the early evolution of the major fish groups alive today, the ray-finned fish.
The find sheds new light on the preservation of the soft parts of skeletal animal fossils, the researchers suggest.
Most of the animal fossils in museum collections were formed from hard body parts such as bones, teeth, and shells.
Dr Sam Giles, lead author at the University of Birmingham, said:
“It tells us more complex patterns of brain evolution than only living species suggest, allowing us to define more precisely when and how modern bony fish evolved.
“When compared to living fish, we found that the brain of the cococephalus most closely resembles that of sturgeon and paddlefish, which predates all other living sturgeons more than 300 million years ago.” They are often called “primitive” fish because they diverged from fish with fins. ”
Researchers analyzed the brain of Cococephalus wildi. Coccocephalus wildi, an early ray-finned fish that likely swam in estuaries and fed on small crustaceans, aquatic insects, and cephalopods, is now a group that includes cuttlefish, octopus, and squid.
Ray-finned fish have spines and fins supported by bony rods called fins.
Soft tissues such as the brain usually decompose rapidly and rarely become fossils, but when this fish dies, the brain, in the process of fossilization, transforms into a dense mineral that retains the three-dimensional structure of the soft tissue. Replaced.
Lead author Rodrigo Figueroa, also from the University of Michigan, commented: Even just the seeds need to be remade. ”
Senior author Matt Friedman of the University of Michigan said: It has been known for over 100 years. ”
The fossil from England is the only known specimen of the species, so scientists could only use techniques that didn’t destroy it.
The skull fossil is on loan from the Manchester Museum to the University of Michigan.
It was first described scientifically in 1925 when it was recovered from the roof of the Mountain Forfoot colliery in Lancashire.
Scientists believe that C. wildi was 6 to 8 inches long and was probably a carnivore, based on the shape of its jaws.
When the fish died, they probably quickly buried themselves in sediment with little oxygen. This is an environment that can slow down the decomposition of soft body parts.
This research is published in Nature.