Scientists discover oldest fossilized brain, dating back to 300 mln yrs

March 3rd, 2009 - 12:25 pm ICT by ANI  

Washington, March 3 (ANI): In a wholly unexpected and rare discovery, scientists have found the oldest brain in fossilized form in Kansas, US, which dates back to 300 million years.
The brain, found in a shale in Kansas and Oklahoma, belong to Iniopterygians, which are extinct relatives of modern ratfishes, also known as “ghost sharks” or chimaeras.
Chimaeras are obscure relatives of sharks and rays that were extensively described by Museum Curator Bashford Dean in 1906 and number about 40 species.
But, in the late Paleozoic, relatives of chimaeras were relatively common in the oceans of the world with a huge diversity of shapes and sizes, and iniopterygians were a bizarre part of this radiation.
The new discovery is described with several other intact braincases-the first three-dimensional fossils from this group of extinct marine fishes.
When Alan Pradel of the Museum National d”Histoire Naturelle in Paris CAT scanned the 300-million-year-old fossilized iniopterygian from Kansas, he and his colleagues saw a symmetrical blob nestled within the braincase.
This turned out to be the oldest brain found in fossil form.
According to John Maisey, curator in the Division of Paleontology at the American Museum of Natural History and a co-author of the report, “Fossilized brains are unusual, and this is by far the oldest known example.”
The new research looked at four 3-dimensional braincases of iniopterygians found in shales from Kansas and Oklahoma.
The specimens share several features with living ratfishes, which means that these skull features have been conserved in the group for the last 300 million years.
Complete reconstructions of these skulls were made with a CAT scan and X-ray synchrotron microtomography, and the imaging of one skull showed a dense, symmetrical object sitting within the large braincase.
This was the mineralized brain.
The specimen that included the brain was imaged as a holtomography by Paul Tafforeau and colleagues at the European Synchrotron Radiation Facility.
This more powerful scan brought the brain to light in great detail.
It is a tiny (about 1.5mm by 7 mm in size), symmetrical shape that sits within a large braincase. As in many lower vertebrates, the brains of these fish ceased to grow as their skulls continued to expand.
The brain has a large lobe for vision and an optic nerve that stretches to the correct place on the braincase; both of these features correlate well with the large eye sockets.
“There is nothing like this known today; it is really bizarre,” said Maisey.
“But now that we know that brains might be preserved in such ancient fossils, we can start looking for others,” he added. (ANI)

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