Most of what we know about ancient, extinct animals comes from their bones, because soft tissues don’t usually fossilize well. But now scientists have found the oldest preserved vertebrate brain in a fossilized fish that is about 320 million years old.
After an animal dies, its flesh and organs usually disappear very quickly, thanks to scavengers and decay. However, soft tissues such as skin and feathers may have survived to this day if the corpse was buried immediately or encased in an amber-like substance to protect it from the elements. can.
Scientists have now discovered the oldest known fossil of a vertebrate brain. The record is for her 319-million-year-old fish known as Coccocephalus wildi, an early ancestor of the ray-finned fishes that make up the largest group of living vertebrates. The previous record holder was a 300-million-year-old shark, but other notable fossil brains include a 310-million-year-old horseshoe crab and a 133-million-year-old dinosaur. will be The oldest known heart, found in a 380-million-year-old fish fossil, is empty.
But the fossils of C. wildi are not a new discovery, they were unearthed from coal mines almost a century ago. But in a new study, researchers performed a CT scan of the specimen to look inside without damaging it and found a bright mass in the skull. This indicates a denser mineral, probably pyrite. The mass looked suspiciously like a brain, the team said: It was centrally symmetrical, with cavities resembling ventricles and filaments that looked like cranial nerves.
“With all these features, I asked myself, ‘Is this really the brain I see?'” said Matt Friedman, senior author of the study. “So we zoomed in on that area of the skull and did a second high-resolution scan, and it was very clear that we needed just that.”
Marcio L. Castro
The researchers say the fish were buried under the sediment soon after they died, and oxygen was almost non-existent, likely preserving them in their original state. A chemical microenvironment conducive to soft tissue fossilization also appeared to have formed within the skull.
The discovery could also fill in some gaps in the evolutionary story of fish. It is most similar to the brains of sturgeon and paddlefish, which are considered to be
“Unlike all living ray-finned fish, the brain of Coccocephalus is folded inward,” Friedman said. “So this fossil captures a period before the characteristic features of the ray-finned fish brain evolved. This gives us some constraints on when this trait evolved. , which until new data on Cococephalus became available, was not well handled.”
The team believes that this type of brain preservation is occurring more frequently than previously thought. In future work, they plan to start looking for them.
A study was published in a journal NatureThe team explains their work in the video below.
300-million-year-old fossil shows evolution of fish brain
Source: University of Michigan
