The trace fossil Sinusichnus from the Upper Ordovician of Anticosti Island, eastern Canada

A significant discovery of the trace fossil Sinusichnus cf. seilacheri in Upper Ordovician (Hirnantian) carbonates on Anticosti Island, eastern Canada, marks the oldest record of this ichnogenus, previously unknown before the Triassic and unreported from North America. These branched, sinusoidal burrows, found abundantly at the base of the Oncolite Bed in the Ellis Bay Formation, indicate a regional discontinuity surface during the multiphase Ordovician mass-extinction event. Unlike Mesozoic and Cenozoic records linked to decapod or isopod crustaceans, these burrows likely represent the activity of other arthropods with unknown affinity, suggesting a combined dwelling, locomotion, and feeding behavior. This finding extends the geological range of Sinusichnus by over 200 million years and provides new insights into Ordovician paleoecology.

Knaust, D., & Desrochers, A. (2020). The trace fossil Sinusichnus from the Upper Ordovician of Anticosti Island, eastern Canada. Lethaia, 53(2), 145–153. https://doi.org/10.1111/let.12347