Sign up for our daily briefing
Make your busy days simpler with Axios AM/PM. Catch up on what's new and why it matters in just 5 minutes.
Catch up on coronavirus stories and special reports, curated by Mike Allen everyday
Catch up on coronavirus stories and special reports, curated by Mike Allen everyday
Denver news in your inbox
Catch up on the most important stories affecting your hometown with Axios Denver
Des Moines news in your inbox
Catch up on the most important stories affecting your hometown with Axios Des Moines
Minneapolis-St. Paul news in your inbox
Catch up on the most important stories affecting your hometown with Axios Twin Cities
Tampa Bay news in your inbox
Catch up on the most important stories affecting your hometown with Axios Tampa Bay
Charlotte news in your inbox
Catch up on the most important stories affecting your hometown with Axios Charlotte
Vaderlimulus horseshoe crab fossil. Photo: New Mexico Museum of Natural History & Science
Before there were birds, mammals and dinosaurs, horseshoe crabs were here. Over the past 450 million years, these relatives of scorpions and spiders (not crabs) passed through five mass extinctions. They stuck to the coasts for the most part so there was little pressure for them to evolve. The horseshoe crabs you see today look similar to their earliest ancestors.
What's new: A recent fossil find in Idaho indicates that in the time in between some ancient horseshoe crabs were more diverse than previously thought. The 245-million-year-old specimen, from when the state sat on the coast of the supercontinent Pangea, is "a missing puzzle piece," Allan Lerner, a research associate in paleontology at the New Mexico Museum of Natural History and Science, tells Axios.
The past: Every now and again, horseshoe crabs ventured out — or rather in — to freshwater environments. When they did, their morphology is thought to have changed. The fossil record during this time is sparse though because horseshoe crabs lack an exoskeleton with minerals that can be preserved except under exceptional conditions.
The discovery: The fossil found in Idaho is so far the only specimen of a new genus called Vaderlimulus with a large — "extravagant would be a good word," Lerner says — helmet and small body that evolved as it expanded into a freshwater environment. Eventually it went extinct though Lerner says they aren't sure why.
The future: This discovery shows horseshoe crabs used to be diverse. But today, only four species remain, and they're in decline due to human actions.
"We shouldn't take for granted that because they have lived as long as they have they will survive," Lerner says.