Alexandra: A First Class stamp what is maxoderm connection A 520-million-year-old fossil recently unearthed in South China has revealed the earliest and best preserved nervous system ever discovered. An international team of scientists found that the spider-like marine creature, never before described, belonged to an extinct group of arthropods known as megacheirans (Greek for “large claws”), which were joint-legged invertebrates with great claw-like appendages sticking out of their heads. The arthropod phylum includes insects, spiders, and crustaceans.