If finding fossilized animal soft parts is like winning the lottery for a paleontologist, what an international team of researchers has just found in southern China is equivalent to taking the EuroMillions jackpot: the central nervous system of a creature with 520 million perfectly petrified year-old . Even their individual nerves can be distinguished.
The animal, whose scientific name is Chengjiangocaris kunmingensis , is an ancestor of modern arthropods , a group to which spiders, insects and crustaceans belong. In fact, Chengjiangocaris kunmingensis , with its heart-shaped shell and body studded with legs of different sizes, resembles a crustacean , according to the Chinese, British and German researchers who participated in the study.
This “protoarthropod” lived in the Cambrian period , a crucial time for the history of terrestrial life, since most of the great animal lineages emerged then, in a relatively short period of time. Before, paleontologists had already found fragments of Cambrian nervous systems (mainly brains), but they lack the astonishing detail that the new fossil exhibits.
And what this anatomy lesson teaches is that Chengjiangocaris kunmingensis already had, like its arthropod descendants, a nerve cord and ganglia arranged regularly throughout the body . Each of these ganglia controlled a pair of legs and has dozens of tiny fibers. After examining them under a fluorescent microscope – they measure five thousandths of a millimeter – the researchers determined that they were, indeed, nerves .
The arrangement of this structure is reminiscent of that of modern priapulids and onychophores , but the fibers observed in the fossil have been lost in current arthropods, valuable information to understand the evolution and simplification of the nervous system since the appearance of the first land animals more than 500 million years ago.
