505-Million-Year-Old Jellyfish Fossils May Be the Oldest Ever Found

Jellyfish have been floating via Earth’s oceans seemingly eternally. But pinning down the precise origin of those squishy sea creatures, that are among the earliest complicated animals, is troublesome. They not often present up within the fossil report as a result of jellyfish are 95 % water and are vulnerable to speedy decay.

“If you see a jellyfish outside of the water, a couple hours later it’s just a ball of goo,” mentioned Jean-Bernard Caron, a paleontologist on the Royal Ontario Museum in Toronto.

But Dr. Caron and different scientists just lately described a cache of jellyfish fossils from the Cambrian interval that discovered an unbelievable pathway to preservation. In a paper printed on Wednesday within the journal Proceedings of the Royal Society B, the scientists posit that these 505-million-year-old animals are among the many oldest swimming jellyfish identified to science.

“These new fossils represent the most compelling evidence of Cambrian jellyfish to date,” mentioned David Gold, a paleobiologist on the University of California, Davis, who was not concerned within the new research.

The jellyfish specimens have been discovered within the Burgess Shale, a fossil-rich web site within the Canadian Rockies that gives a glimpse of life throughout Earth’s Cambrian explosion. Like different soft-bodied creatures discovered on the web site, the gelatinous jellyfish are preserved in gorgeous element. Most nonetheless possess upward of 90 fingerlike tentacles, which stick out of the creature’s bell-shaped physique just like the strings on the finish of a tassel rug. Some even retain their abdomen contents and gonads.

Back within the Nineties, Royal Ontario Museum researchers unearthed greater than 170 jellyfish fossils from the Raymond Quarry in British Columbia. When Dr. Caron and a Ph.D. pupil examined the specimens extra just lately, they realized the fossils represented a brand new species, which they named Burgessomedusa phasmiformis.

The species is a part of a various group known as medusozoans, that are thought to have originated at the least 600 million years in the past and are nonetheless swimming in the identical seas we all know right this moment. But proof of their rise is scarce. Most fossils from earlier than the Cambrian interval are both microscopic or little greater than faint imprints, making it troublesome to deduce how these ancestral jellies lived.

Over the previous 20 years, paleontologists have found a number of well-preserved jellyfish-like fossils from websites in Utah and China which can be related in ages to the Burgess Shale. However, the true identities of those creatures continues to be up for debate. In the brand new paper, Dr. Caron and his colleagues proposed that the fossils from Utah and China characterize historic ctenophores, or comb jellies, one other group of gelatinous animals solely distantly associated to true jellyfish.

Not all researchers are bought by this reclassification. According to Bruce Lieberman, a paleontologist on the University of Kansas who studied the Utah fossils, the brand new paper lacks compelling proof to attach the sooner fossils with comb jellies. Instead, he thinks Burgessomedusa joins a swarm of jellyfish species that patrolled Cambrian seas. “It really adds to the compelling body of evidence indicating that medusozoans, which are a really important clade in the oceans today, were already established by the time of the Cambrian period,” Dr. Lieberman mentioned.

The researchers assume that including jellyfish to the Burgess Shale’s miniature menagerie provides one other layer of complexity to Cambrian ecosystems. With a physique that grew to almost eight inches lengthy, Burgessomedusa was among the many bigger creatures round.

According to Dr. Gold, Burgessomedusa’s bell-like form is paying homage to trendy field jellyfish, that are potent predators that pack a lethal sting. “Box jellyfish are active hunters and use their bell for active reorientation and bursts of speed to go after prey,” Dr. Gold mentioned. However, Burgessomedusa seems to lack a number of sensory buildings present in trendy jellyfish. “It’s unclear if it had the eyes modern box jellies use to hunt,” Dr. Gold mentioned.

Even with out eyes, Burgessomedusa was prone to have been a high predator. Like trendy jellyfish, it most likely specialised on smaller fare. But it seems to have additionally been able to looking comparatively huge recreation: One Burgessomedusa specimen studied within the paper was preserved with a trilobite lodged inside its bell.

The means of jellyfish to seize prey whereas drifting via the ocean regardless of being virtually fully composed of water has made them the oceans’ most enduring predators.

“Burgessomedusa demonstrates how little the basic jellyfish body has changed,” Dr. Gold mentioned. “They have survived relatively unchanged for hundreds of millions of years.”