Relationship between dietary niche breadth and species durations of canids in the John Day community

Abstract Increased dietary specialization has been considered a significant predictor for risk of extinction within the fossil record. However, these interpretations typically come from species-level morphological assessment of diets aggregated across a broad geographic extent. Using the exceptional fossil record of the John Day Formation, we reconstructed dietary niche breadth for the regional community of canids via morphological tooth traits and dental microwear textures to assess how measures of dietary behavior and plasticity might influence species durations. We found that signals of dietary behavior, as inferred from dietary niche breadth estimated via dental microwear textures, showed a stronger relationship with lineage durations than did morphological tooth traits. Specifically, dietary niche breadth was negatively associated with increased species durations. These results suggest the relationship between overall dental morphology and dietary behaviors is more nuanced than previously expected and that the contribution of dietary flexibility irrespective of tooth morphology to extinction risk deserves further attention.