Paleontologist Matt Friedman was stunned when he discovered a remarkably detailed 319-million-year-old fish brain fossil while testing CT scans for a wider project.
“He had all these features,” says Friedman of the University of Michigan, “and I thought, ‘Is this really the brain of what I’m seeing?’
Usually, the only traces of this ancient life left are the hard parts of animals that are easier to preserve, such as bones, as the soft tissues break down quickly.
A scientist accidentally discovered the oldest brain of Any vertebrate https://t.co/tJWERU3Iqo
— ScienceAlert (@ScienceAlert) February 2, 2023
But in this case, a dense mineral, possibly pyrite, leaked out and replaced the tissue, which probably lasted much longer in a low-oxygen environment. This made it possible to scan what appear to be details of the cranial nerve and soft tissues of the tiny fish Coccocephalus wildi.
It is the only ancient specimen of its kind, so despite being in the hands of researchers since it was first described in 1925, this feature has remained hidden because scientists would not risk using invasive research methods.
Friedman explains: “Here we find the amazing preservation of a fossil that has been examined many times by many people over the last century. But since we have these new tools for studying fossils, they open up another layer of information for us.”
These prehistoric estuarine fish probably preyed on insects, small crustaceans and cephalopods, chasing them with flippers supported by bony rods called rays.
Rayfish, a subclass of Actinopterygii, make up over half of all spineless animals living today, including tuna and seahorses, and 96% of all fish.
This group of lobe-finned fish split off about 450 million years ago. C. wildi then went on its own evolutionary path among the fish populations that are still alive today, some tens of millions of years ago.
“The analysis takes this taxon out of the group that includes all extant ray-finned fish. Details of the brain structure of Coccocephalus have implications for the interpretation of neuromorphology in the early stages of the evolution of this major vertebrate lineage,” wrote University of Michigan paleontologist Rodrigo Figueroa and colleagues. in their newspaper.
Some features of the brain would have been lost due to the decay and conservation process, but the team could still identify certain morphological details. This allowed them to see that the evolutionary path of this prehistoric forebrain was more similar to ours than to the rest of living ray-finned fish.
Friedman notes: “Unlike all living ray-finned fishes, the brain of Coccocephalus is folded inwards. Therefore, this fossil reflects the time before this characteristic feature of the ray-finned fish brain evolved. This gives us some restrictions on when this trait evolved. . .
Researchers are keen to scan other fish fossils in museum collections for other signs of soft tissue that may be lurking inside.
“The important takeaway is that such soft parts can be preserved, and they can be preserved in the fossils that we have for a long time — this is a known fossil from more than 100 years ago,” Friedman says. It is very important to preserve the physical samples. Who knows what else might come of it. What will people do with the fossils in our collections now, 100 years from now?
This study is published in the journal Nature.
Source: Science Alert
You must log in to post a comment.