The researchers ran the analysis on digital reconstructions of the appendages, to figure out how much stress they could handle. For comparison, they did the same for a different ancient arthropod, Sidneyia inexpectans — a known shell-crusher — as well as the horseshoe crab. They then compared the results.
O. serratus, they found, likely did not have the ability to break into shelled creatures — its long spines would have snapped, Dr. Bicknell said. Instead, it likely used those spines to shred detritus and soft prey such as worms, the way we might flake steamed fish apart with a fork.
R. rex, however, was apparently built to crush. According to the analysis, its appendages could withstand more force than those of the horseshoe crab. It may have specialized in consuming shelled prey, including other trilobites, and even other Redlichia, Dr. Bicknell said.
This type of virtual experimentation allows for a deeper look into “the function of anatomical parts that cannot be tested otherwise,” said Karen Moreno, a paleontologist at the Austral University of Chile, who was not involved in the study.
But because certain information — such as a trilobite’s muscle positions or the material properties of its exoskeleton — is unknown and must be approximated, she said, exact measurements and firm conclusions are impossible. Instead, making comparisons with creatures we better understand, like the horseshoe crab, lets experts “search for patterns — approximations that will drive future investigations.”
Asked whether he would like to finally answer some of these questions once and for all — through a time-traveling snorkeling trip, for example — Dr. Bicknell said yes.
“The Cambrian was effectively when arthropods ruled the world,” he said. “It would just be so beautiful to see — beautiful may not be the right word. But interesting.”