Overview
- A peer-reviewed Nature study, published Wednesday, describes Megachelicerax cousteaui as the oldest known chelicerate.
- The specimen preserves chelicerae—pincer-like front appendages that replace antennae in this group—marking the earliest clear example of these hallmark mouthparts.
- The find moves the chelicerate fossil record about 20 million years earlier and supports the view that chelicerae evolved from grasping “great appendages.”
- Collected in Utah’s Wheeler Formation in the early 1980s, the hand-sized fossil yielded a head shield, nine trunk segments, and book gill–like respiratory structures after more than 50 hours of meticulous preparation.
- Researchers infer an aquatic predator that cruised near the seafloor and used its claws to lift worm prey, tightening links between Cambrian forms and later horseshoe crab–like relatives.