Occlusal enamel complexity in middle miocene to holocene equids (Equidae: Perissodactyla) of North America.
Authors: Famoso Nicholas A, Davis Edward Byrd
Journal: PloS one
Summary
# Editorial Summary: Occlusal Enamel Complexity in Equids Through Deep Time Understanding how equine dentition evolved provides crucial context for recognising normal anatomical variation and wear patterns in modern horses. Famoso and Davis (2014) employed quantitative analysis of occlusal enamel complexity across four equid groups spanning 16 million years, using statistical modelling to examine how phylogeny, tooth position, and climate influenced the development of chewing surface architecture. Their findings demonstrated a clear correlation between increasing dietary abrasion, cooling climates, and greater enamel complexity—essentially, horses that faced harsher environmental conditions and more abrasive forage developed more convoluted occlusal patterns that increased the cutting surface area available during mastication. Only the Equini lineage persisted to the modern era, whilst other equid groups became extinct despite their own adaptive strategies, suggesting that occlusal design alone was insufficient to ensure survival. For equine practitioners, this evolutionary perspective reinforces why contemporary horses—products of selection for relatively consistent diets and environments—may show limited individual variation in enamel pattern compared to their wild ancestors, and why modern dental pathologies often reflect a mismatch between evolved dentition and contemporary management practices.
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Practical Takeaways
- •Modern horse teeth show greater occlusal complexity than ancestral forms, reflecting adaptation to more abrasive diets and environmental pressures over evolutionary time
- •Understanding dental morphology evolution provides context for modern equine dental disease and the variation seen in contemporary horse populations
Key Findings
- •Occlusal enamel complexity increased significantly in equids from middle Miocene to modern times in response to increased dietary abrasion
- •Climate change, phylogeny, and tooth position were all significant influences on the evolution of occlusal enamel patterns
- •Four distinct equid groups coexisted in the middle Miocene but only Equini survived 16 million years of evolution and extinction