Dating back 520 million years, the clawed spider-like fossil shows clear evidence of a brain and of nerve cords running through the creature's trunk. The specimen now confirms that the ancestors of spiders and scorpions were related, but branched off more than half-a-billion years ago. The "great appendage" arthropods, are an extinct group of joint-legged creatures with large claw-like appendages - or growths - protruding from their heads. The nervous system tends to be similar between major groups of animals, which helps palaeontologists work out how they are related, explained Greg Edgecombe from the Natural History Museum in London.
New to science, the fossil was recently discovered in South China and is part of the genus Alalcomenaeus. This group had segmented bodies equipped with about a dozen pairs of appendages which enabled the creatures to swim or crawl. It was placed in a CT scanner and compared with other arthropods in order to understand its evolution. The team then used 3D software to see structures not visible on the surface of the fossil.
The fossil belongs to an extinct group of marine arthropods known as megacheirans, Greek for "large claws". To infer the evolutionary relationships between species, the fields of palaeontology and neuroanatomy together.