Twenty million years ago, the shores of northern Taiwan were sandstone sediments at the bottom of the sea, where 6-foot-long worms hid in their burrows, waiting for unsuspecting prey to pass over them.d. Now, a team of geoscientists has chronicled 319 fossils of these carnivorous sea worms, whose dens fossilized in Miocene mud.
“At first, we were firmly convinced that it was a very elegant burrow,” Ludvig Löwemark, a sedimentologist at Taiwan National University, said in a video call. “And then, after talking to some other experts, we opted for this bivalve hypothesis. But, in the end, we became more and more convinced that it was actually a bobbit worm that made this trail ”.
Trace fossils are vestiges of the creatures that created them: footprints and other hardened remains of the movements of animals in life, rather than the fossil remains of creatures. The worms that the researchers suggest once inhabited these burrows have disappeared, presumably composed of soft tissues that deteriorated shortly after death. An analysis of the fossils is published today in the journal Scientific Reports.
The Löwemark team, led by Yu-Yen Pan at Taiwan National University, discovered hundreds of black spots dotting the rocky coast of Taiwan. They found that the holes were oriented horizontally as they deepened, forming a boomerang-shaped den about 1 inch wide and 6 feet deep. The sharp bend in the den suggested to the team that the ground under the creature became harder to dig to a certain depth or became more anoxic. (Worms breathe through the skin, so if the soil in which they are immersed does not have enough oxygen, it can be fatal).
G / O Media may receive a commission
Where the burrows opened to the bottom of the sea, there was a “leady” pattern that the team identified, which suggested that the silty seabed had collapsed around the funnel-shaped structure. indicative of a void left by a creature stretching again. his lair. They concluded that the animals that made the dens were close relatives of today’s killer bobbit worms, which still grow up to 10 feet long and were named after an infamous Criminal case of the 90s with a severed penis (although it might be time to do so) to change this name). Traces of fossils are called in Taiwan Pennichnus bonic!, which means “beautiful trail of feathers”, the latter name deriving from the Portuguese name of Taiwan, Formosa.
“It really doesn’t matter who did it, it’s the shape and function of the fossil trail that gets its name,” Löwemark said. “So you have a genus for similar traits, fossils that were produced in a specific way, due to eating behavior or locomotion or whatever … and then you have a species name.”
Having eliminated other culprits: the shrimp would have left “sprouting” cameras in their dens, while the worms are more than a one-way operation and a bivalve suspect would have had an ass the lair where he marked space for his shell : a predatory ambush worm seemed to fit the profile. Today, the bobbit worm hunts by sensation: when it detects a disturbance outside its lair, the worm launches into the as yet unidentified organism, lightning, armed with hard tongs. When it has good retention, the worm pulls the prey into its den and the sand sinks over the entrance and hides the horrible scene. If you blinked, you would never know what happened.
“It’s a very brutal procedure,” Löwemark explained.
When we think about it on a scale — the team found hundreds of these burrows in two places along the coast — it looks like a scary, reverse mole-beating game.