TechCanadian scientists uncover oldest known jellyfish fossil from 500 million years ago

Canadian scientists uncover oldest known jellyfish fossil from 500 million years ago

This is what a jellyfish looked like 500 million years ago.
This is what a jellyfish looked like 500 million years ago.
Images source: © Christian McCall

6:54 AM EST, January 21, 2024

Jellyfish are amongst the most ancient animal families. These somewhat eccentric beings, however, are seldom well preserved in the fossil record because their bodies, akin to sponges, comprise about 95 percent water. As such, the fossils uncovered by the Canadian scientists are highly unusual.

Preserved jellyfish from 505 million years ago

Joe Moysiuk and his team from the University of Toronto analyzed fossilized remains from Cambrian shale from Burgess. Particularly striking is the Burgess Shale jellyfish, known as Burgessomedusa phasmiformis - the oldest known example of a free-swimming jellyfish in the fossil record. This creature existed 505 million years before dinosaurs roamed the Earth.

Their analysis, the findings shared in Proceedings of the Royal Society B: Biological Sciences, revealed that the animal was about 7.87 inches tall and had up to 90 short, finger-like "tentacles" on its body. These allowed it to hunt large prey effectively. Detailed anatomical features of this jellyfish are also discernible.

Jellyfish traces on the stones
Jellyfish traces on the stones© Royal Ontario Museum | Desmond Collins

"Even though jellyfish are thought to be one of the earliest animal groups, identifying them in the Cambrian fossil record is incredibly challenging," said Moysiuk. His team's discovery nevertheless casts light on specific aspects of these creatures' evolution.

For instance, it's becoming apparent that the body structure of modern jellyfish, with their characteristic bell shape, emerged very early in the evolution of this animal group. "This is an exceptional discovery," added co-author Dr. Jean-Bernard Caron.

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