New Findings Indicate that Mysterious Creature from 500 Million Years Ago Did Not Prey on Trilobites

The Cambrian period, which occurred from 541 to 485 million years ago, marked the evolution of the first animals with hard protective parts, such as trilobites. These marine arthropods had mineralized shells that covered their entire bodies, often adorned with spikes. However, signs of bite marks and missing pieces suggested the existence of a predator capable of cracking even the toughest shells. For a long time, an enigmatic group of shrimp-like creatures called anomalocarids, with no modern relatives, were the primary suspects.

Anomalocaris canadensis, discovered in the late 1800s, was widely believed to be responsible for the scarred and crushed trilobite exoskeletons found in the fossil record. With its large size, equivalent to that of a 5-year-old child in a period when most creatures were smaller than a human hand, and its two arachnid-like appendages beneath its head along with razor-like teeth in its mouth, this creature seemed to be the apex predator during the Cambrian period.

However, a recent biomechanical study suggests that the actual living animal was likely much weaker than previously thought. It probably relied on agility and speed to feed in open waters, swiftly chasing after soft prey rather than pursuing hard-shelled creatures on the ocean floor.

Contrary to earlier assumptions, the reconstructed jaws of Anomalocaris turned out to be weaker than believed, and the “teeth” were flexible plates used for grinding down soft tissue. The question remains: could Anomalocaris have used its peculiar appendages to crush trilobites?

The idea of Anomalocaris being a trilobite killer didn’t seem plausible due to trilobites’ robust exoskeletons, made essentially of rock, while Anomalocaris would have been predominantly soft and squishy. Russel Bicknell, the lead author of the study and a postdoctoral researcher from the American Museum of Natural History’s Division of Paleontology, who conducted the research at the University of New England in Australia, expressed doubts about this theory.

This research involved building a 3D reconstruction of A. canadensis using extraordinarily well-preserved, albeit flattened, fossils found in Canada’s Burgess Shale, which dates back 508 million years. By comparing the living analogs of whip scorpions and whip spiders, the research team demonstrated that A. canadensis‘s segmented appendages were capable of gripping and stretching.

However, through the use of finite element analysis, a modeling technique commonly employed in simulating the stability of buildings, it was revealed that Anomalocaris‘s appendages would have been damaged while attempting to grasp hard prey like trilobites.

When combining these biomechanical modeling techniques, which were used together for the first time in a scientific paper, a different understanding of A. canadensis emerged. It is now believed that this hungry animal fed on soft-bodied prey, capturing victims with its outstretched appendages while they were out of the water. By closing its appendages, it created a cage-like structure around its mouth, preventing any chance of escape.

The identity of the predator responsible for the bite marks on trilobites remains a mystery.

“We’re discovering that the dynamics of Cambrian food webs were much more complex than previously thought,” concluded Russell Bicknell.

The study, “Raptorial appendages of the Cambrian apex predator Anomalocaris canadensis are built for soft prey and speed,” authored by Bicknell and a team of scientists from several countries, was published in the Proceedings of the Royal Society B: Biological Sciences (2023). Additional information was provided by the American Museum of Natural History.

Denial of responsibility! TechCodex is an automatic aggregator of the all world’s media. In each content, the hyperlink to the primary source is specified. All trademarks belong to their rightful owners, and all materials to their authors. For any complaint, please reach us at – [email protected]. We will take necessary action within 24 hours.