The “terror monsters” were like the sharks of the ancient seas 518 million years ago

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Long before the first sharks appeared, large predatory worms were “terror monsters” in the seas more than 500 million years ago, according to new research.

Scientists have discovered fossils of previously unknown worm species during expeditions in northern Greenland, revealing what they believe are some of the oldest carnivores.

The worms reached approximately 1 foot (30 cm) in length and were some of the largest swimming animals of their time, known as the Early Cambrian.

The researchers named the worms “timorpestia,” which is Latin for “terror monsters.” Fins ran down the sides of their bodies, and their distinctive heads had long antennae and huge jaws.

Previously, primitive arthropods, including strangely shaped distant relatives of crabs and lobsters called Anomalocaris, were thought to have been at the top of the marine food chain during the Ice Age. Cambrian periodWhich lasted from 485 million to 541 million years ago.

But predatory worms were an essential part of the ecosystem 518 million years ago, and scientists didn't know they existed until they found the fossils. A study describing the findings was published Wednesday in the journal Advancement of science.

“The Timorbestia were giants of their time and would have been near the top of the food chain,” study senior author Dr Jacob Vinther, associate professor of macroevolution in the Schools of Earth and Biosciences at the University of Bristol, said in a statement. .

“This makes them equivalent in importance to some of the most important carnivores in the modern oceans, such as sharks and seals dating back to the Cambrian period,” Vinther said. “Our research shows that these ancient ocean ecosystems were fairly complex with a food cascade that allowed several levels of predators to coexist.”

During the Cambrian Period when carnivorous predators appeared, animals “evolved explosively for the first time,” Venter said. “It has had an enormous impact on carbon and nutrient cycles as well as on the pace of evolution.”

These predatory worms are distant relatives of smaller modern arrowworms, or chaetognath worms, that feed on zooplankton, Finther said.

Arrowworms are among the oldest animals that originated in the Cambrian period. Arthropods first appeared between 521 and 529 million years ago, while evidence of arrowworms suggests they have been around for 538 million years.

“Both arrowworms and the more primitive Timorbeastia worms were swimming predators,” Venter said. “So we can assume that it was most likely these predators that dominated the oceans before the arthropods took off. They probably had a lineage about 10 to 15 million years old before other, more successful groups took their place.”

Isoxys was preserved inside the fossilized digestive system of Timorpistia, a swimming arthropod that had long protective spines that pointed forward and backward.

“However, it is clear that they did not completely succeed in avoiding this fate, because Timorbestia ingested them in large quantities,” study co-author Morten Lunde Nielsen, a former doctoral student at the University of Bristol, said in a statement.

The researchers said that revealing details about Timorbestia provides a window into the evolutionary timeline of the worms from half a billion years ago to the present day.

“Today, arrowworms have dangerous bristles on the outside of their heads to catch prey, while Timorbestia has jaws inside their heads,” study co-author Luke Parry, an assistant professor of paleobiology at the University of Oxford, said in a statement.

“This is what we see in today's microscopic jawed worms – organisms with which arrowworms share an ancestor more than half a billion years ago. Timorbestia and other fossils like it provide links between closely related organisms that today look very different.”

Modern arrowworms have a distinct nervous system on their abdomens called the ventral ganglion, which has been found preserved in Timorpestia as well, said lead study author Dr. Tae-yeon Park, a principal research scientist at the Korea Polar Research Institute. The nervous system has also been observed in another fossil called Amescoia, suggesting that the soft-bodied animal is also evolutionarily related to arrowworms.

Park led a research team on expeditions to Sirius Basset, a well-preserved fossil site in far northern Greenland. The sun shines all day at the remote site, which is 600 miles (966 kilometers) from the North Pole, Vinther said. Researchers have a small window of about six weeks each year when a site is available, but it's worth the trip, he said.

“Fossils are so dense here, compared to any other area, that every time you split the rocks, you reveal dozens to hundreds of soft-bodied fossil organisms,” Vinther said.

Members of the research team are eager to return to Sirius Basset, where they discovered fossilized remains of other relatives of Timorbestia, to gain a better understanding of the ocean's first food chain.

“Thanks to the remarkable and exceptional preservation of Sirius Basset, we can also reveal exciting anatomical details including the digestive system, muscle anatomy, and nervous system,” Park said. “We have many exciting results to share in the coming years that will help show what the first animal ecosystems looked like and evolved.”