An international team of researchers determined that the brain of ancient arthropods had a certain part in its structure, traces of which are preserved in the living species of these creatures.
Arthropods are the most diverse and species-rich group of animals. These include insects, crustaceans, spiders, scorpions, and millipedes.
Scientists have long assumed that the ancestors of this group had a different brain structure than their contemporaries. This concerns the anterior region of the organ, which is unsegmented and invisible in living arthropods. Although this part of the brain is not visible, it gives rise to several important neural centers that are involved in decision making and memory. This area was named prosocerebrum.
Scientists from Guizhou University, the Shanghai Advanced Research Institute of the Chinese Academy of Sciences, the universities of Barcelona (Spain) and Arizona (USA) have studied the fossils of one of the ancestors of arthropods - Leanchoilia - and confirmed the presence of a similar structure in his brain. The study was published in the journal Current Biology.
The authors of the work found that about 500 million years ago, the anterior part of the arthropod brain already existed and was structurally different from the forebrain, middle and hindbrain of modern representatives of the group.
The fossils studied also shed light on the evolution of the two visual systems of arthropods - a pair of forward-facing and side-facing eyes that are still preserved in some arthropod species today. The eyes are also associated with the prosocerebrum, in addition, this part of the brain is related to the upper "lip" of modern arthropods.