The owner is a pet that has been extinct for 250 million years
That the find corresponds to the “most ancient fossil brain that we know of,” says Nicholas Strausfeld, a professor in the Department of Neuroscience at the University of Arizona. The brain in question would belong to a specimen of Cardiodiction ( Cardiodictyon catenulum ) an extinct animal belonging to the lobopoda , which lived about 520 million years ago (Lower Cambrian). His remains were found in the Maotianshan deposit in China.
The lobopoda include the entire group of now extinct animals, with a segmented body and legs, which, however, are not easily classifiable in any group of the arthropod phylum.
Until recently, the conventional wisdom was that “brains don’t fossilize,” said researcher Frank Hirth, lecturer in evolutionary neuroscience at King’s College London. “So first and foremost, you don’t expect to find a fossil with a preserved brain ,” he explained. “And secondly, this animal is so small that one would not even dare to look at it in the hope of finding a brain.”
Instead the Cardiodiction, already found in 1984, amazed everyone because its fossil preserves a perfectly preserved tiny nervous system.
Cardiodiction’s brain identification wasn’t the study’s only finding. It has always been believed that ancient brains were extremely different from those of modern arthropods – that is, the richest group of species in the animal kingdom that includes insects, crustaceans, arachnids, millipedes and centipedes, and so on – but, as anatomical studies have shown detailed and genomic analyses, were rather similar.
“By comparing known gene expression patterns in living species, we have identified a feature common to all brains and how they are formed,” Hirth said. “We realized that each brain domain and its corresponding characteristics are the result of the same combination of genes, regardless of the species examined.” “This suggests a common genetic blueprint for brain formation,” she added.
This would prove that dear Cardodoction would be one of our earliest ancestors.
- The lower Cambrian lobopodian Cardiodictyon resolves the origin of euarthropod brains. (science.org)