Oldest species of swimming jellyfish discovered in 505m-year-old fossils

Subject :Geography

Section: Physical Geography

Context:

The oldest species of swimming jellyfish ever recorded has been discovered in 505m-year-old fossils.

Details:

The fossils were found at Burgess Shale in Canada, an area known for the number of well-preserved fossils found there.
The new species, which has been named Burgessomedusaphasmiformis, resembles a large, swimming jellyfish with a saucer or bell-shaped bodyup to 20cm high.
Its roughly 90 short tentacles would have allowed it to capture sizable prey.
The discovery of Burgessomedusaphasmiformis has shown that the Cambrian food chain was much more complex than previously imagined.

About Jellyfish:

Jellyfish belong to a subgroup of cnidaria, the oldest group of animals to exist, called medusozoans.
Jellyfish are mainly free-swimming marine animals with umbrella-shaped bells and trailing tentacles, although a few are anchored to the seabed by stalks rather than being mobile.
They are made of 95% water and decay quickly, so fossilized specimens are rarely found, but the specimens – found in the late 1980s and early 1990s – were exceptionally well preserved.
Jellyfish, along with their relatives, have been “remarkably hard to pin down in the Cambrian fossil record” despite being part of one of the earliest groups of animals.
Jellyfish are found all over the world, from surface waters to the deep sea.

Burgess shale, Canada:

The Burgess Shale is a fossil-bearing deposit exposed in the Canadian Rockies of British Columbia, Canada.
It is famous for the exceptional preservation of the soft parts of its fossils.
At 508 million years old (middle Cambrian), it is one of the earliest fossil beds containing soft-part imprints.
The rock unit is a black shale and crops out at a number of localities near the town of Field in Yoho National Park and the Kicking Horse Pass.
Another outcrop is in Kootenay National Park 42 km to the south.