The nervous system provides a fundamental source of data for
understanding the evolutionary relationships between major arthropod groups1,
2. Fossil arthropods rarely preserve neural tissue. As a result, inferring
sensory and motor attributes of Cambrian taxa has been limited to interpreting
external features, such as compound eyes3 or sensilla decorating appendages4,
and early-diverging arthropods have scarcely been analysed in the context of
nervous system evolution. Here we report exceptional preservation of the brain
and optic lobes of a stem-group arthropod from 520 million years ago (Myr ago),
Fuxianhuia protensa5, exhibiting the most compelling neuroanatomy known from
the Cambrian. The protocerebrum of Fuxianhuia is supplied by optic lobes
evidencing traces of three nested optic centres serving forward-viewing eyes.
Nerves from uniramous antennae define the deutocerebrum, and a stout pair of
more caudal nerves indicates a contiguous tritocerebral component. Fuxianhuia
shares a tripartite pre-stomodeal brain and nested optic neuropils with extant
Malacostraca and Insecta2, 6, demonstrating that these characters were present
in some of the earliest derived arthropods.
journal reference (only the abstract free): nature >>