2024-01-05 12:11:00
“A past dynasty of predators that scientists never knew existed.” This is what researchers from the Universities of Bristol and Oxford (England) discovered by identifying new fossils at Sirius Passet, in the northern part of Greenland.
In this deposit — in paleontology and geology, an exceptional fossil site which presents a remarkable preservation of organic remains — from the Cambrian (542 million years ago to 488 million years ago), they had already discovered a fauna of around forty-five species (arthropods, trilobites, sponges, annelids, lobopods, euarthropods, brachiopods), depending on the site Arctic Research of the National Center for Scientific Research (CNRS).
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But the new fossil animals identified, “giant worms” named Timorebestia (“fright beasts”, in Latin) and described in the magazine Science Advances this January 3, 2024, are of a particular kind: they could be among the first carnivores to have colonized the water column more than 518 million years ago, explain the authors of the study in a communiqué.
Giant predator worms more than half a billion years old have been discovered in North Greenland!
Dr Jakob Vinther is part of a team of scientists to unearth the fossil animals which have been named Timorebestia, meaning ‘terror beasts’ in Latin.
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— University of Bristol (@BristolUni) January 4, 2024
In the Cambrian, a sudden appearance of new animals
THE Timorebestia had fins, long distinctive antennae, massive jaws inside their mouths, and could reach… more than 30 centimeters. If that’s not impressive millions of years later, make no mistake, they were aptly named “dread beasts” in their time, explains lead author of the study Jakob Vinther , from the Schools of Earth and Biological Sciences at the University of Bristol:
Timorebestia was a giant of his time and would have been near the top of the food chain. This makes it equivalent in importance to some of the major carnivores of modern oceans, such as sharks and seals during the Cambrian Epoch.
As the website of the National Museum of Natural Historyduring the Cambrian explosion around 530 million years ago, an impressive diversity of new animals appeared.
Among them can be counted a wide variety of arthropods presenting a then unprecedented form of skeleton, with a composition close (chitin, proteins, carbonate) to that of the heterogeneous group of current arthropods (insects, arachnids, myriapods, crustaceans, chelicerates).
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One of the giants of this period, the Titanokorys gainesi, an anthropoid identified in 2022 in the Burgess Shale – famous for the importance of the numerous discoveries made there – thus reached 50 centimeters. But the record is currently held by the “sea monster” Anomalocarisan extinct genus of arthropods just under a meter long.
But if arthropods dominated the Cambrian seas with their imposing “build”, this new research shows “that these ancient ocean ecosystems were quite complex, with a food chain allowing for several levels of predators”explains the specialist.
Car Timorebestia was part of another phylum (phylum), which constitutes a very ancient zoological enigma: it was a “distant, but close relative” chetognaths (Chaetognatha), oceanic predators also called “sagittarius worms” because of their arrow shape.
Photograph (scanning electron microscopy, SEM) of a “Chaetognatha”. Wikimedia Commons / Zatelmar
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Missing links in the evolution of marine predation
If today, the chetognaths are much smaller and feed on zooplankton, inside the fossilized digestive system of Timorebestiaresearchers discovered the remains of a Isoxys…or a small primitive arthropod. “We can see that these arthropods were a food source for many other animalsdevelops Morten Lunde Nielsen, former doctoral student at Bristol and member of the study. [Malgré] their long protective spines, pointing both forward and backward […] Timorebestia devoured them in large quantities.”
While arthropods appear in the fossil record around 521 to 529 million years ago, “sagittarius worms” can be found earlier, at least 538 million years ago.
The latter are therefore the oldest animal fossils from the Cambrian, and in their capacity as swimming predators, they “probably dominated the oceans before the emergence of arthropods”suppose Dr Jakob Vinther. “Perhaps they had a dynasty of about 10 to 15 million years before being supplanted by other, more successful groups”the famous arthropods.
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Timorebestia ultimately constitutes one of the missing pieces of the evolutionary puzzle of the chetognaths, with a distinct nerve center on their belly (ventral ganglion), unique to their group. Nowadays, they also have menacing bristles on the outside of their heads to seize their prey, while the fossil animal, however, hides them inside its mouth.
Greenland expedition leader and other lead author of the report, Tae Yoon Park of the Korea Polar Research Institute, concluded the statement:
Thanks to the remarkable and exceptional preservation at Sirius Passet, we can […] reveal exciting anatomical details about such unique predators, including their digestive systems, muscular anatomy and nervous systems.
On the same topic :
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