According to recent findings, the fossil of a 520-million-year old creature has been so well conserved that it still displays its individual nerve fibers.
Researchers have conducted a study on this ancient animal that originated from southern China and they’ve concluded that this fossil displays the oldest central nervous system ever discovered.
Since an animal’s nervous system and soft tissues are composed of degradable substances, most fossils usually reveal bones, as well as other hard body parts, like teeth.
What sets this discovery apart is that it offers a unique insight into what the ancient nervous system looked like. According to the study’s co-author Javier Ortega-Hernandez from the University of Cambridge, this is the most unitary archetype of a central nervous system from the Cambrian time.
The detailed fossil belongs to a creature called Chengjiangocaris kunmingensis, which lived during the Cambrian explosion, a period that saw a rapid evolutionary development.
This event, also known as the Cambrian radiation, occurred some 542 million years ago and it is the time when most major animal phyla surfaced on Earth.
The C. kunmingensis is an anthropod called a fuxhianhuiid, and is basically an ancient cousin of our present-day insects, spiders and crustaceans.
The researchers’ investigation revealed a nerve cord present throughout its body, which resembles the human spinal cord. This animal had a single pair of legs, which were controlled through various bundles of nerve cells.
When the team of scientists analyzed the fossil, they discovered numerous spindly fibers, each of them being about five thousandths of a millimeter long.
Ortega-Hernandez explains that these fragile fibers revealed a regular distribution pattern, which made the researchers want to discover whether they were made from the same fabric as the cells forming the nerve cord.
In order to conduct this study, they used a method called fluorescence microscopy, which offered the scientists an unprecedented amount of information. Through this technique, they were able to confirm that the fibers were indeed individual nerves that had been fossilized as carbon films.
During their analysis they also discovered that certain aspects of this animal’s nervous system resemble the one found in modern velvet worms and penis worms. As it turns out, all of these organisms display regularly spaced nerves, which spread out from the central nerve cord.
According to Ortega-Hernandez, if the scientists discover more of these fossils, then they will be better equipped to understand how the nervous system and early creatures evolved.
The study was published on February 29th in the journal Proceedings of the National Academy of Sciences.
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