“Brains don’t fossilize.” So the scientific community had determined. However, researcher Nicholas Strausfeld from the University of Arizona (USA) challenged this theory in a study – not without criticism – published in 2012 in the journal Nature. Now, new research offers clear evidence : brains also fossilize.
Strausfeld together with scientists from the University of Yunnan (China) and the Natural History Museum in London (United Kingdom) have analyzed seven newly discovered fossils of the same species , finding traces of a brain in each of the specimens.
The species in question is Fuxianhuia protensa , an extinct arthropod that roamed the bottom of the oceans some 520 million years ago . Thanks to scanning electron microscopy, the scientists observed how the brains had been preserved as flattened carbon films, covered in some of them by small crystals of iron pyrite.
But how is a brain fossilized?
Apart from the fact that the animal has to be buried quickly, the neural tissue of the Fuxianhuia protensa had to be quite dense, enough that once the stage becomes an oxygen-starved space, the tissues successfully overcome this phase: “During this process, the brain maintains its overall integrity, leading to its gradual flattening and preservation. The tissue density of ‘F. Protensa ‘seems to have made all the difference, ”explains Strausfeld.
According to the work, the results of the analysis of these seven fossils provide irrefutable evidence that the fossilized brains of primitive arthropods are much more than a single isolated phenomenon or an implausible fossilization event.
The study has been published in the journal Current Biology .
