All posts tagged: 500millionyearold

500-million-year-old fossil rewrites a missing chapter of Earth’s history

500-million-year-old fossil rewrites a missing chapter of Earth’s history

A remarkable fossil hidden in a museum collection for decades is helping scientists rethink one of the biggest mysteries in early animal evolution. The discovery of a 500-million-year-old arthropod in eastern Canada suggests that a period once thought to be marked by declining biodiversity may have been far richer and more complex than researchers believed. The newly described species, named Magnicornaspis garwoodi, comes from the late Cambrian Period and belongs to a rare group of extinct arthropods known as corcoraniids. These ancient creatures are considered important relatives of the lineage that eventually gave rise to modern chelicerates, a group that includes spiders, scorpions and horseshoe crabs. Researchers say the fossil provides valuable evidence from a poorly understood interval known as the Furongian, a period spanning roughly 497 million to 485 million years ago. For decades, paleontologists have puzzled over why relatively few fossils appeared to come from this time. The new findings suggest the apparent shortage may not reflect a true collapse in life on Earth. Instead, it may reveal gaps in where scientists have …

500-million-year-old spider relative has claws where it shouldn’t

500-million-year-old spider relative has claws where it shouldn’t

Get the Popular Science daily newsletter💡 Breakthroughs, discoveries, and DIY tips sent six days a week. The fossil was completely unremarkable. That’s what Harvard University paleontologist Rudy Lerosey-Aubril initially thought while examining an arthropod fossil dating back to the Cambrian period (538.8 million to 485.4 million years ago).  “As I prepared it, however, it unexpectedly revealed exquisitely preserved limbs—including a pair of frontal claws projecting from the head,” Lerosey-Aubril tells Popular Science. Early arthropod specimens don’t have claws like these. Instead, Cambrian arthropods usually have an antenna in that position. In other words, the claws Lerosey-Aubril was seeing were not supposed to be there.  This unassuming fossil belongs to Megachelicerax cousteaui, a 500-million-year-old sea predator. The fossil was first dug up over 40 years ago in a desert in western Utah and is the oldest known chelicerate—the arthropod group that includes modern spiders, scorpions, horseshoe crabs, and sea spiders. This single strange specimen pushes the evolutionary history of chelicerates back by 20 million years and helps explain the evolution of claws. The findings are detailed …