The Rabbitkettle Formation is a widespread lower Paleozoic unit in the northern Cordillera. A trilobite faunule collected from the middle part of the type section and described here documents an early Ibexian (Early Ordovician) age for this interval and provides the first biostratigraphic reference point for the type section. This faunule is dominated by the agnostoid Micragnostus, the leiostegiid Leiostegium, and the remopleuridid Kainella. These genera and rarer taxa have North American, South American, and Austral-Asian affinities. A new species, Kainella eleutherolfi, is established.