Millions of years in the past, big predatory worms so long as an grownup human terrorized the ocean. The fearsome creatures hid below the ocean flooring, ready to grab unwitting prey with their slicing jaws and drag them underground to be consumed — like they do as we speak, just lately found fossils recommend.
The fossils are “very, very distinctive,” mentioned Shahin Dashtgard, a professor of earth sciences at Simon Fraser University in Burnaby, B.C., who co-authored a brand new examine describing them.
“They’re like nothing we’ve ever seen before in the rock record.”
Unlike conventional fossils which might be normally shaped from the exhausting elements of an animal’s physique, resembling its bones or shell, the worm fossils are “trace fossils” consisting of non-biological traces resembling footprints or, on this case, a burrow. The fossils are described in a study published this week in the journal Scientific Reports.
Dashtgard famous that as a result of worms have delicate our bodies, they’re not often fossilized.
“So, the burrows they make is really the only record we have of what the ecosystem would look like and how diverse the ecosystem was.”
Evoke the monsters of science fiction
The researchers suggest that the traditional worm was much like the modern-day Bobbit worm or sand striker, a marine predator that lives in tropical and subtropical seas within the Indo-Pacific Region and grows as much as three metres lengthy. It hides in underground burrows with simply its head uncovered, hanging and grabbing prey, resembling fish or shellfish with sharp, scissor-like jaws and dragging them into its burrow.
Bobbit worms are named for the slicing capacity of their jaws, which was likened to the slicing that abused wife Lorena Bobbit did to take away her husband’s penis in 1989. They have additionally been in comparison with sand crawling monsters in science fiction worlds resembling Star Wars, Dune and Tremors.
Bobbit worms and their family members are thought to have existed for a really very long time. Fossil jaws of what’s regarded as the oldest Bobbit worm have been found in a 400 million year old rock formation in Ontario.
But as a result of they’re delicate, worms are not often discovered within the fossil report.
That’s why researchers have begun on the lookout for hint fossils of soft-bodied marine animals. Ludvig Löwemark, a professor of geosciences at National Taiwan University and Masakazu Nara, a professor of organic sciences at Kochi University in Japan, two co-authors of the examine, have been on the lookout for hint fossils of one other historical animal after they got here throughout one thing uncommon in a 20 million-year-old sandstone formation in Taiwan.
Figuring out what it was turned the mission of Yu Yen Pan, a grasp’s pupil working with Löwemark who’s now a PhD pupil at Simon Fraser University.
Key piece of the puzzle
The rock the place the fossils have been initially discovered, Badouzi promontory, was an historical continental shelf about 30 or 40 metres beneath the floor of the ocean, mentioned Pan. It was seemingly much like the atmosphere discovered off the coast of Taiwan as we speak. Other fossil proof exhibits that it was seemingly a coral reef populated by animals resembling stingrays and different fish, sea urchins and crustaceans resembling shrimp and lobsters.
The first fossils have been largely fragments left behind by erosion, so the researchers determined to search for comparable fossils in one other a part of the identical rock layer a ways away in an space referred to as Yehliu Geopark.
It wasn’t lengthy earlier than Löwemark referred to as Pan over. He had discovered an entire fossil, beginning with a funnel on the high that narrows to a cylindrical tube about three centimetres in diameter, descending straight into the bottom for 70 or 80 centimetres, earlier than bending horizontally into an L-shape, reaching a complete size of about two metres
“We were super excited,” Pan recalled. “This really could help us to connect the puzzle together and make the story more complete.”
In complete, the researchers discovered 319 fossil specimens on the two websites. A chemical evaluation of the fossils discovered they have been excessive in iron, which is typical of burrows made by soft-bodied animals. That’s as a result of they have a tendency to stabilize their burrows with mucus that pulls microbes that enrich the sediment with iron.
The incontrovertible fact that the tunnel was L-shaped additionally urged that it was made by a soft-bodied animal, as such animals cannot dig too deep earlier than the bottom will get too exhausting and compacted for them to proceed, and they should begin digging horizontally.
The burrows have been completely different in dimension and form from burrows created from different animals, resembling eels or razor clams.
But when the researchers in contrast the fossil burrows to the burrows of recent Bobbit worms, which inhabit fashionable ecosystems not a lot completely different from people who the fossil was present in, they appeared very comparable.
Dashtgard suggests meaning the worms have been dwelling in the same atmosphere for fairly a very long time — about 20 million years.
‘Feathery footprint’ from Taiwan
The researchers named their new fossil Pennichnus formosae. The first a part of the title refers back to the feathery (“penna” in Latin) “footprint” (“ichnus” in Latin) left within the high “funnel” of the burrow by the way in which the sediments have been disturbed when the animal pulled its prey inside. “Formosae” after Formosa, a former title for Taiwan, honours the place it was discovered,
Pan mentioned the fossil is notable as a result of it gives clues about looking behaviour of an historical invertebrate, one thing that’s fairly uncommon.
David Rudkin was one of many researchers who studied the Ontario Bobbit worm jaw fossils however was not concerned within the hint fossil examine. Rudkin, a retired assistant curator on the Royal Ontario Museum and a retired lecturer on the University of Toronto, mentioned whereas he is not an knowledgeable in hint fossils, he discovered the interpretation within the new examine “pretty convincing.”
“The kicker, of course, would be finding a direct association in the form of either ‘jaw’ elements or soft-body bits within the burrows, left after the animal died in place,” he mentioned in an electronic mail.
Unfortunately, the circumstances that protect burrows and people who protect our bodies are typically fairly completely different, so that they’re not often discovered collectively, he mentioned.
“Under the circumstances,” he mentioned, “I think the authors have done a nice job of making the case for these being Bobbit burrows!”
More burrows more likely to be discovered
Murray Gingras is professor on the University of Alberta who research traces made by fashionable animals and compares them to the fossil report. He wasn’t concerned within the new examine however has gone to Australia to review the burrows of recent Bobbit worms as a part of his personal analysis.
One problem with hint fossils, he mentioned, is that many animals could make very comparable traces and determining which one any given hint got here from requires some interpretation. But on this case, he thinks the researchers’ interpretation is affordable and properly argued.
“I think it’s a fun discovery,” he mentioned.
He mentioned he is shocked such fossil burrows have not been discovered earlier than given how widespread Bobbit worms are and the way conspicuous their burrows are.
He suspects that many extra shall be discovered now that different researchers know what to search for, and that may assist uncover the animals’ actions and distribution over the previous 20 million years.