- New research suggests spiders and other arachnids may have originated in the sea, based on analysis of a 500-million-year-old fossil.
- University of Arizona researchers studied the “exquisitely preserved” brain of Mollisonia symmetrica, an extinct Cambrian-period species.
- The fossil's neural structure was found to resemble modern spiders and their relatives, rather than horseshoe crabs, as previously believed.
- A key feature identifying the fossil as an early arachnid is its unique brain organization, which appears “flipped backwards” similar to modern spiders.
- This discovery challenges the common belief that arachnid diversification happened only after a common ancestor transitioned to land.
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