Computed tomographic analysis of dental system of three Jurassic ceratopsians: implications for the evolution of the tooth replacement pattern and diet in early-diverging ceratopsians

The dental system of ceratopsids is among the most specialized structure in Dinosauria, and includes high angled wear surfaces, split tooth roots, and multiple teeth in each tooth family. However, the early evolution of this unique dental system is generally poorly understood due to a lack of knowledge of the dental morphology and development in early-diverging ceratopsians. Here we study the dental system of three of the earliest-diverging Chinese ceratopsians: Yinlong and Hualianceratops from the early Late Jurassic of Xinjiang, and Chaoyangsaurus from the Late Jurassic of Liaoning. By using micro-computed tomographic analyses, our study has revealed significant new information regarding the dental system of these early ceratopsians, including no more than five replacement teeth in each jaw quadrant; at most one generation of replacement teeth in each alveolus; nearly full resorption of the functional tooth root during tooth replacement; and occlusion with low-angled, concave wear fac...

角龙科（Ceratopsidae）的齿系是恐龙总目（Dinosauria）中特化程度最高的结构之一，具备高角度磨损面、分裂型齿根，以及每个齿家族内拥有多颗牙齿的特征。然而，由于对早期分化角龙类的牙齿形态与发育机制缺乏认知，这类独特齿系的早期演化历程长期以来普遍认知不足。本研究针对三类最早分化的中国角龙类齿系展开研究：分别为产自新疆早晚侏罗世的尹龙（Yinlong）与华丽角龙（Hualianceratops），以及产自辽宁晚侏罗世的朝阳龙（Chaoyangsaurus）。本研究通过显微计算机断层扫描（micro-computed tomography）分析，揭示了这些早期角龙类齿系的多项全新重要信息，包括单个颌骨象限内的替换齿数量不超过5颗、每个齿槽内最多仅存在一代替换齿、牙齿替换过程中功能齿根几乎完全被吸收，以及匹配低角度凹面磨损面的咬合关系……