Fossil trackways are simultaneously wonderful and frustrating things. They are preserved bits of prehistoric behavior, but, unless an animal actually dies and becomes preserved in its tracks, identifying exactly what creature left the traces can be fraught with difficulty. (The types of prehistoric environments which preserved tracks often destroyed body fossils, so, when the two are found together, ichnologists celebrate.) Every now and then, though, paleontologists discover a creature which became fossilized with the impressions it left behind. Such is the case with a Cambrian trilobite discovered in the Czech Republic.

The trilobite fossil described by Oldrich Fatka and Michal Szabad is subtle, but significant. At the end of a short burrow is the body of the trilobite Agraulos ceticephalus, leaving no question as to the animal which created the trace. The fossil may even provide some insight into how this trilobite was feeding. Though described as a "burrow" in the paper's title, Fatka and Szabad argue that the trace might be part of a feeding trail. Agraulos ceticephalus may have been a common, bottom-feeding animal which helped form the base of the prehistoric food web. Perhaps, now that trace and trace-maker have been found together, additional burrows or feeding imprints might be found and thus provide paleontologists with a small glimpse at the behavior of the long-lost trilobites.

Top Image: The trilobite Agraulos ceticephalus at the end of a small, light-colored trace fossil it created. From Fatka and Szabad, 2011.

References:

Fatka, O., & Szabad, M. (2011). Burrowing trilobite caught in the act Paläontologische Zeitschrift DOI: 10.1007/s12542-011-0102-4