Scientists in northern Greenland, Denmark, have discovered a new collection of fossils of extinct predatory animals in the Sirius Passet region, dating back to the early Cambrian era. This group, represented by large worms, may be among the earliest carnivorous animals that dominated the oceans for over 518 million years, revealing a previously unknown lineage of predatory animals.
The newly discovered fossilized animals are named “Timorebestia” (Timorebestia), meaning “terrorist monsters” in Latin. These adorned creatures had fins on the sides of their bodies, distinctive heads with long sensory horns, massive jaw structures inside their mouths, and grew to over 30 cm in length, making them among the largest swimming animals in the early Cambrian era.
Dr. Jacob Vinther from the Faculty of Earth Sciences and Biological Sciences at the University of Bristol, one of the senior authors of the new study, noted that Timorebestia is “related to the living arrow worms, or as known, the jaw-spine animals, which are much smaller predators today that feed on small animal plankton.”
Vinther added, “Our study shows that ancient ocean ecosystems were somewhat complex, with a food chain that allowed for the presence of several levels of predatory animals. Timorebestia was a giant in its era and was close to the top of the food chain. This makes it as significant as some of the top carnivorous animals in modern oceans, such as sharks and seals in the Cambrian era.”
Inside the fossilized digestive system of the ancient Timorebestia worm, scientists at the University of Bristol found evidence of its last meal, a small creature called Isoxys (meaning equal surfaces). Scientists speculate that these small arthropods may have a lineage dating back to “about 10 to 15 million years before being replaced by other groups.”
Morten Lund Nielsen, a former doctoral student at the University of Bristol and part of the current study, stated, “We can see that these arthropods were a food source for many other animals. They were very common in the Sirius Passet area and had long protective spines. However, it is clear that they did not entirely succeed in avoiding this fate, as Timorebestia eliminated them in large quantities.”
Arrow worms are among the oldest animal fossils that lived in the Cambrian era. While arthropods appear in the fossil record from about 521 to 529 million years ago, arrow worms can be traced back to at least 538 million years ago.
Tai Yun Park from the Korean Polar Research Institute, another senior author and leader of the field mission, emphasized, “Our discovery confirms how arrow worms evolved. Living arrow worms have a distinctive nerve center in their abdomen, called the ventral ganglion. It is extremely unique for these animals. We found this preserved in Timorebestia and another fossil called Amiskwia. We are very excited to discover such unique predatory animals in Sirius Passet.
During a series of exploratory trips to the extremely remote Sirius Passet in northern Greenland, over 82.5 degrees north, we collected a wide variety of exciting animals. New living organisms. Thanks to the excellent and exceptional preservation in Sirius Passet, we can also reveal exciting anatomical details, including the digestive system, muscle anatomy, and the nervous system.”
Dr. Park concluded, “We have many exciting results to share in the coming years that will help illustrate how the first animal ecosystems looked and evolved.”
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