A fossil discovered in Canada has revealed the oldest preserved adult jellyfish known to date, dating back over 500 million years. The remains were found in the Burgess Shale, a fossil-rich deposit in the Canadian Rockies that has yielded remarkably well-preserved marine organisms from the past.
The Burgess Shale is renowned for its exceptional preservation, including the presence of intact eyes, stomachs, and even preserved last meals inside some specimens, according to Joe Moysiuk from the University of Toronto. However, many of these fossils have remained untouched in the Royal Ontario Museum in Toronto since their excavation in the 1980s and 1990s.
Among these fossils, Moysiuk and his colleagues identified the earliest record of an adult jellyfish, belonging to a new species named Burgessomedusa phasmiformis. The researchers gave it this name because they thought its body shape resembled the ghost from the video game Pac-Man. The ancient jellyfish shares many similarities with its modern counterparts, measuring 20 centimeters long with a bell-shaped body and more than 90 tentacles.
The jellyfish was caught in an undersea mud flow around 500 million years ago, which quickly buried it and preserved it over time. This discovery suggests that jellyfish had already developed their complex life cycle, consisting of two distinct stages (polyps and medusas), at least half a billion years ago.
Earlier excavations in the area have revealed 560-million-year-old fossils of jellyfish polyps. However, this finding represents the first evidence of a large swimming jellyfish from this time period. It provides valuable insights into the evolutionary history of jellyfish and their early development.
Insights:
- The Burgess Shale in Canada is a rich deposit of fossils, which has provided exceptional preservation of ancient marine organisms, including jellyfish.
- The discovery of a 500-million-year-old adult jellyfish fossil sheds new light on the early evolution and development of jellyfish.
- The fossil belongs to a newly identified species named Burgessomedusa phasmiformis, which had a ghost-like appearance resembling the character from the video game Pac-Man.
- This finding suggests that jellyfish had already developed their complex life cycle at least half a billion years ago.
- Previous excavations have found fossils of jellyfish polyps, but this is the first evidence of a large swimming jellyfish from that time period.
