Comparison of diverse mandibular mechanics during biting in Devonian lungfishes.

Fossil lungfish from the Late Devonian Gogo Formation, Australia, feature some of the most remarkable and specialized mandible morphologies in their 415-million-year history. Although the taxonomy, systematics, and species diversity are relatively well understood, their ecological role and how multiple species could co-exist in the same ecosystem remain unclear. Using 3D finite element analysis, this study assesses species-specific mechanical performance of fossil lungfish mandibles. Our models predict that gracile mandibles experience highly variable bone stress magnitudes during biting, but intensity is contingent on dentition type (shape), occurring more within the "denticulated" morphology, and less for "tooth-plated" or "dentine-plated" forms. In contrast, robust mandibles experience lower bone stress overall, but symphysis length remains significant, possibly withstanding high torsional forces. Our comprehensive dataset offers the most detailed quantification of biting performance in any fossil fish thus far, providing biomechanical evidence for diverse feeding adaptations and niche partitioning within Gogo lungfishes.