Ultramicrostructural reductions in teeth: implications for dietary transition from non-avian dinosaurs to birds

Zhiheng Li, Chun-Chieh Wang, Min Wang, Cheng-Cheng Chiang, Yan Wang, Xiaoting Zheng, E-Wen Huang, Kiko Hsiao, Zhonghe Zhou

Research output: Contribution to journalArticlepeer-review


Background Tooth morphology within theropod dinosaurs has been extensively investigated and shows high disparity throughout the Cretaceous. Changes or diversification in feeding ecology, i.e., adoption of an herbivorous diet (e.g., granivorous), is proposed as a major driver of tooth evolution in Paraves (e.g., Microraptor, troodontids and avialans). Here, we studied the microscopic features of paravian non-avian theropod and avialan teeth using high-spatial-resolution synchrotron transmission X-ray microscopy and scanning electron microscopy. Results We show that avialan teeth are characterized by the presence of simple enamel structures and a lack of porous mantle dentin between the enamel and orthodentin. Reduced internal structures of teeth took place independently in Early Cretaceous birds and a Microraptor specimen, implying that shifts in diet in avialans from that of closely related dinosaurs may correlate with a shift in feeding ecology during the transition from non-avian dinosaurs to birds. Conclusion Different lines of evidence all suggest a large reduction in biting force affecting the evolution of teeth in the dinosaur-bird transition. Changes in teeth microstructure and associated dietary shift may have contributed to the early evolutionary success of stemward birds in the shadow of other non-avian theropods.

Original languageEnglish
Article number46
Number of pages8
JournalBMC Evolutionary Biology
Issue number1
StatePublished - 21 Apr 2020


  • Tooth
  • Avialan
  • Feeding ecology
  • Non-avian dinosaurs

Cite this