POSSIBLE TRILOBITE-IN-TRILOBITE SHELTERING BEHAVIOR (SILURIAN GUN RIVER FORMATION, ANTICOSTI ISLAND, CANADA)

Fossils typically preserve only the shape of an animal and remain silent on how the organism lived. On rare occasions, fossils are preserved in such a way as to record evidence of the animals’ behavior. This study documents possible evidence of an enrolled trilobite belonging to the genus Acernaspis sheltering within a large isolated pygidium belonging to another genus of trilobite, Arctinurus. This fossil was recovered from float material collected from the Silurian Gun River Formation on Anticosti Island (Quebec, Canada).

Sheltering behavior has been previously documented in trilobites, with trilobites sheltering in the remains of other invertebrates as well as in burrows. Inferring behavior from assemblages such as this is difficult and requires certain assumption. This study explores alternate interpretations of the association and their implications.