500-Million-Year-Old Fossil Identified as Oldest Known Chelicerate
Paleontologists at Harvard University have described a large predatory arthropod from the Middle Cambrian of Utah featuring massive three-segmented chelicerae. Named Megachelicerax cousteaui, this soft-bodied animal represents the earliest known member of the chelicerates, pushing back the origins of spiders, scorpions, horseshoe crabs, and sea spiders by 20 million years. The surprisingly complex anatomy of…