The unidentified blob was brighter on the CT image-and therefore likely denser-than the bones of the skull or the surrounding rock. “I scanned it, then I loaded the data into the software we use to visualize these scans and noticed that there was an unusual, distinct object inside the skull,” he said. wildi, Friedman was not looking for a brain when he fired up his micro-CT scanner and examined the skull fossil. The goal of the larger study is to obtain internal anatomical details that provide insights about evolutionary relationships. The work on Coccocephalus is part of a broader effort by Friedman, Figueroa and colleagues that uses computed tomography (CT) scanning to peer inside the skulls of early ray-finned fishes. The eye sockets are the large, black oval areas surrounded by bone, and the jaws are below the eye sockets. The brain and cranial nerves appear bright white in the center of the images. CT scan of the Coccocephalus wildi skull, showing the fossilized brain and associated structures. The skull fossil from England is the only known specimen of its species, so only nondestructive techniques could be used during the U-M-led study. From now on, our research group and others will look at fossil fish heads with a new and different perspective.” “With the widespread availability of modern imaging techniques, I would not be surprised if we find that fossil brains and other soft parts are much more common than we previously thought. “Not only does this superficially unimpressive and small fossil show us the oldest example of a fossilized vertebrate brain, but it also shows that much of what we thought about brain evolution from living species alone will need reworking,” Figueroa said. The other senior author is Sam Giles of London’s Natural History Museum and the University of Birmingham. The lead author is U-M doctoral student Rodrigo Figueroa, who did the work as part of his dissertation, under Friedman, in the Department of Earth and Environmental Sciences. “An important conclusion is that these kinds of soft parts can be preserved, and they may be preserved in fossils that we’ve had for a long time-this is a fossil that’s been known for over 100 years,” said U-M paleontologist Matt Friedman, a senior author of the new study and director of the Museum of Paleontology. Photo credit: Jeremy Marble, University of Michigan News. Pulled from a coal mine in England more than a century ago, the fossil is the oldest example of a well-preserved vertebrate brain. University of Michigan paleontologist Matt Friedman examines CT scan images of an exceptionally preserved, 319-million-year-old fossilized fish brain. When the fish died, the soft tissues of its brain and cranial nerves were replaced during the fossilization process with a dense mineral that preserved, in exquisite detail, their three-dimensional structure. Ray-finned fishes have backbones and fins supported by bony rods called rays. The CT-scanned brain analyzed for the new study belongs to Coccocephalus wildi, an early ray-finned fish that swam in an estuary and likely dined on small crustaceans, aquatic insects and cephalopods, a group that today includes squid, octopuses and cuttlefish. Most of the animal fossils in museum collections were formed from hard body parts such as bones, teeth and shells. The serendipitous find also provides insights into the preservation of soft parts in fossils of backboned animals. The discovery opens a window into the neural anatomy and early evolution of the major group of fishes alive today, the ray-finned fishes, according to the authors of a University of Michigan-led study scheduled for publication Feb. The brain and its cranial nerves are roughly an inch long and belong to an extinct bluegill-size fish. The CT-scanned skull of a 319-million-year-old fossilized fish, pulled from a coal mine in England more than a century ago, has revealed the oldest example of a well-preserved vertebrate brain. Study: Exceptional fossil preservation and evolution of the ray-finned fish brain DOI 10.1038/s41586-1 This fish would have been 6 to 8 inches long, about the size of a bluegill. The eye socket is the circular, bumpy feature above the jaws. The fish is facing to the right, with the jaws visible in the lower right portion of the fossil. The fossilized skull of Coccocephalus wildi, an early ray-finned fish that swam in an estuary 319 million years ago.
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