The Trilobite Diet

A digital reconstruction of the trilobite's gut contents

Trilobites hold a prized position in the Earth’s fossil record, a benchmark that signals the beginning of the Cambrian Explosion and the rapid diversification and advancement of life. Still, much remains unknown about these creatures—their tough outer shells fossilized easily, leaving their inner workings often poorly preserved. Now, a rapidly fossilized Bohemolichas incola has given a glimpse into a fundamental life function of trilobites: their diet. To this point, trilobite eating habits were speculated on based on the physical remains of the specimens; for the first time, actual food has been preserved in a fossil, a step forward in understanding the creatures.

The trilobite specimen was found in the Czech Republic’s Šárka Formation, encased in a siliceous nodule. The trilobite in question was rapidly buried and preserved soon after its final meal, persevering not just the animal but its gut contents as well. Its digestive tract is lined with the fossilized remains of ostracods and other small crustaceans, suggesting scavenging behavior in this particular genus. Based on the number of shells and their placement in the specimen, the study’s authors are able to speculate on the shape of the digestive tract and the rest of its inner anatomy that does not fossilize as well.

A Phacops trilobite (Source: Thomas Bresson)

Understanding the trilobite’s digestive tract in turn allows us to understand the rest of the creature’s anatomy. To compensate for the animal’s apparently quite large digestive chambers, the trilobite would need long and sturdy appendages to move about effectively. The well-preserved mini fossils in the trilobite’s gut also suggest a neutral pH, as high acid levels would have corroded what remains of the creature’s prey. These features can in turn be compared against the living anthropods, allowing for a construction of the evolutionary links between the animals.

Through this discovery, much can be gleaned about trilobites, not just about their digestive functions but their entire anatomy and the evolution of their living ancestors. Trilobites are some of the best-represented fossils on the record, with 20,000 species documented, but until now much of what we knew about their feeding was confined to speculation. With this exceptional fossil, we have a better understanding of these ancient sea creatures.

Interested in picking up a trilobite fossil for yourself? You can find them right here, including some jewelry specimens!