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 ground, ready to grab unwitting prey with their slicing jaws and drag them underground to be consumed — like they do right this moment, just lately discovered fossils recommend.
The fossils are “very, very distinctive,” stated 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 have ever seen earlier than within the rock file.”
Unlike conventional fossils which can be often shaped from the laborious components of an animal’s physique, resembling its bones or shell, the worm fossils are “hint fossils” consisting of non-biological traces resembling footprints or, on this case, a burrow. The fossils are described in a examine printed this week within the journal Scientific Reports.
Dashtgard famous that as a result of worms have gentle our bodies, they’re not often fossilized.
“So, the burrows they make is admittedly the one file we now have of what the ecosystem would seem like and the way numerous the ecosystem was.”
Evoke the monsters of science fiction
The researchers suggest that the ancient worm was just 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 spouse 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 are thought to have existed for a really very long time. Fossil jaws of what’s regarded as the oldest Bobbit worm have been present in a 400 million yr outdated rock formation in Ontario.
But as a result of they’re gentle, worms are not often discovered within the fossil file.
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 ancient animal once they got here throughout one thing uncommon in a 20 million-year-old sandstone formation in Taiwan.
Figuring out what it was turned the venture of Yu Yen Pan, a grasp’s scholar working with Löwemark who’s now a PhD scholar at Simon Fraser University.
Key piece of the puzzle
The rock the place the fossils have been initially discovered, Badouzi promontory, was an ancient continental shelf about 30 or 40 metres under the floor of the ocean, stated Pan. It was doubtless just like the atmosphere discovered off the coast of Taiwan right this moment. Other fossil proof reveals that it was doubtless a coral reef populated by animals resembling stingrays and different fish, sea urchins and crustaceans resembling shrimp and lobsters.
The first fossils have been principally fragments left behind by erosion, so the researchers determined to search for comparable fossils in one other a part of the identical rock layer far away in an space known as Yehliu Geopark.
It wasn’t lengthy earlier than Löwemark known as Pan over. He had discovered a whole fossil, beginning with a funnel on the prime 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 have been tremendous excited,” Pan recalled. “This actually may assist us to attach the puzzle collectively and make the story extra full.”
In whole, 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 proven fact that the tunnel was L-shaped additionally steered that it was made by a soft-bodied animal, as such animals cannot dig too deep earlier than the bottom will get too laborious and compacted for them to proceed, and they should begin digging horizontally.
The burrows have been completely different in measurement and form from burrows made out of 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 cutting-edge ecosystems not a lot completely different from people who the fossil was present in, they appeared very comparable.
Dashtgard suggests which means the worms have been residing in an analogous 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 identify refers back to the feathery (“penna” in Latin) “footprint” (“ichnus” in Latin) left within the prime “funnel” of the burrow by the best way the sediments have been disturbed when the animal pulled its prey inside. “Formosae” after Formosa, a former identify for Taiwan, honours the place it was discovered,
Pan stated the fossil is notable as a result of it gives clues about searching behaviour of an ancient 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, stated whereas he is not an skilled in hint fossils, he discovered the interpretation within the new examine “fairly convincing.”
“The kicker, in fact, can be discovering a direct affiliation within the type of both ‘jaw’ components or soft-body bits inside the burrows, left after the animal died in place,” he stated in an electronic mail.
Unfortunately, the circumstances that protect burrows and people who protect our bodies are typically fairly completely different, in order that they’re not often discovered collectively, he stated.
“Under the circumstances,” he stated, “I believe the authors have finished a pleasant job of creating the case for these being Bobbit burrows!”
More burrows prone to be discovered
Murray Gingras is professor on the University of Alberta who research traces made by cutting-edge animals and compares them to the fossil file. 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 stated, 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 cheap and properly argued.
“I believe it is a enjoyable discovery,” he stated.
He stated 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 can be discovered now that different researchers know what to search for, and that can assist uncover the animals’ actions and distribution over the previous 20 million years.