505 Million-Year-Old Fossil Bed in Canada Reveals the Oldest Known Species of Swimming Jellyfish

In a 505-million-year-old Canadian fossil bed, more than 170 exquisitely preserved fossils of ancient jellyfish were found, predating dinosaurs. These fossils, including the newly discovered species Burgessomedusa phasmiformis, showcase rare soft tissue preservation, displaying visible anatomical details like their tentacles.

Paleontologist Joe Moysiuk from the University of Toronto and the Royal Ontario Museum emphasized in a news release the significance of this discovery, as jellyfish and their relatives have been elusive in the Cambrian fossil record despite being considered one of the earliest animal groups to evolve.

Oldest Swimming Jellyfish Date Back to the Cambrian Period

The majority of existing fossil record mainly consists of durable skeletal remains, as they have a higher chance of surviving the fossilization process. Soft tissues, being more delicate and prone to degradation, are much rarer in the fossil record. However, a special type of fossil bed, called a lagerstätte, offers a glimpse into the preservation of soft tissues.

According to Science Alert, the Burgess Shale in Canada is a well-known lagerstätte that has remarkably preserved various soft-bodied animals from the Cambrian period. These creatures fell into the fine silt of an ancient body of water, where the interplay of time and pressure worked their magic to preserve them, often even including soft tissue.

Jellyfish, belonging to the phylum Cnidaria, are primarily composed of soft tissue, making their preservation in the fossil record an uncommon occurrence.

Although fossils of polyp-type cnidarians, the early life stage of modern jellyfish, have been found dating back up to 560 million years ago, the fossil record lacked medusae (free-swimming jellyfish) specimens, complicating the understanding of their evolutionary transition.

While some previous fossils were initially thought to be jellyfish, they were later identified as comb jellies, belonging to a different phylum called Ctenophora. The find confirms that these remarkable creatures were indeed present and swimming in the ancient oceans during the Cambrian Period, Science Alert reported .

Discovery of Jellyfish Fossil Sheds Light on the Species' Evolution

The revelation of Burgessomedusa provides a fresh starting point for understanding the evolution of jellyfish. It also underscores the remarkable diversity of Cambrian marine ecosystems, which might appear to be dominated by hard-shelled creatures due to their better preservation as fossils. However, the reality suggests a complex and rich ecosystem, featuring a variety of soft-bodied predators as well.

Paleontologist Jean-Bernard Caron of the Royal Ontario Museum expresses awe at the discovery of such exquisitely delicate animals preserved in rock layers atop these mountains.

Yoho and Kootenay National Parks house the renowned Burgess Shale fossil sites, managed by Parks Canada, as per Phys.org. Collaborating with top scientific researchers, Parks Canada takes pride in enhancing our understanding of this crucial era in Earth's history and offers award-winning guided hikes to showcase these sites to the world.

Recognized for its exceptional global significance, the Burgess Shale received the prestigious UNESCO World Heritage Site designation in 1980 and is now a component of the larger Canadian Rocky Mountain Parks World Heritage Site.

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