The Korean and British researchers who have discovered and analyzed the first fossils of this species have had no qualms about assigning it a grandiloquent name and referring to its size with the adjective “giant.” Scientifically, the name (the discoverers have this right) and the adjective are accepted, taking into account the comparative size of similar beings of the time. But for ordinary mortals, in this case, the name does not do the trick.
The name attributed to the new species of fossil worm (lived about 500 million years ago) found in northern Greenland is specifically Timorebestia koprii, where the first part means terrifying beast (from Latin) and the second is simply a recognition of the Korea Polar Research Institute (KOPRI), where several of the co-authors of the discovery work.
By size, some of the remains of the “giant” had a body length of 20 centimeters, 29 if the antennas are included, as detailed by the authors in the article presenting the results of their study, published in the journal Science Advances.
Fossils of this new group of predatory animals have been located at the Sirius Passet fossil locality, in northern Greenland. The authors consider that these worms can be considered the first large carnivorous animals that colonized the water column about 518 million years ago (at the beginning of the Cambrian period).
Fossils show that these animals previously unknown to science had fins on the sides of their body, a distinctive head with long antennae, and jaw structures inside their mouth.
“We already knew that early arthropods were the dominant predators during the Cambrian, such as the strange-looking anomalocarids,” said Professor Jakob Vinther, an expert from the School of Earth Sciences and Biological Sciences at the University of Bristol and lead author. of the study. “However, Timorebestia is a relative – distant in time but not in shape – of the current arrow worms or chaetognaths.” The current relatives are much smaller oceanic predators and feed on tiny zooplankton,” says Professor Vinther. .
“The Timorebeasts were giants of their time and would have been near the top of the food chain. That makes them equivalent in importance to some of the major carnivores of the modern oceans, such as sharks and seals in the Cambrian period.”
Inside Timorebestia’s fossilized digestive system, researchers found remains of a common swimming arthropod called Isoxys. “We can see that these arthropods were a food source for many other animals,” said Morten Lunde Nielsen, a former Ph.D. Student in Bristol and part of the current study.
“They are very common on Sirius Passet and had long protective spines that pointed both forward and backward. However, they clearly failed to avoid that fate, because Timorebeast chewed them up in large quantities.”
Arrow worms are one of the oldest animal fossils from the Cambrian. While arthropods appear in the fossil record between 521 and 529 million years ago, arrow worms date back at least 538 million years.
Professor Vinther considered that “both the arrow worms and the more primitive Timorebeast were swimming predators. Therefore, we can assume that in all probability they were the predators that dominated the oceans before arthropods appeared. Perhaps they had a dynasty of about 10 – 15 million years before they were replaced by other groups.”
Luke Parry from the University of Oxford, who was part of the study, added: “The Timorebeast is a really significant find for understanding where these jawed predators came from. Today, arrow worms have menacing bristles on the outside of their head to catch its prey, while the Timorebeast has jaws inside its head.”
“Our discovery confirms how arrow worms evolved,” said Tae Yoon Park of the Korean Polar Research Institute, co-senior author and leader of the field expedition that located the fossils. “Living arrow worms have a distinct nerve center in their belly, called the ventral ganglion. It’s completely unique to these animals.”
“We are very excited to have discovered such unique predators on Sirius Passet. Over a series of expeditions in northern Greenland we have collected a great diversity of exciting new organisms and thanks to the remarkable and exceptional conservation of Sirius Passet, we also “We can reveal interesting anatomical details, including its digestive system, muscular anatomy and nervous system.”