Acta Scientiarum Naturalium Universitatis Pekinensis ›› 2024, Vol. 60 ›› Issue (2): 239-248.DOI: 10.13209/j.0479-8023.2024.002

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Study of the Tooth Replacement of Chaohusaurus brevifemoralis from the Lower Triassic of Chaohu, Anhui Province

GU Shulun, JIANG Dayong, ZHOU Min   

  1. The Key Laboratory of Orogenic Belt and Crustal Evolution (MOE), School of Earth and Space Sciences, Peking University, Beijing 100871
  • Received:2023-04-04 Revised:2023-04-25 Online:2024-03-20 Published:2024-03-20
  • Contact: JIANG Dayong, E-mail: djiang(at)


顾书纶, 江大勇, 周敏   

  1. 造山带与地壳演化教育部重点实验室, 北京大学地球与空间科学学院, 北京 100871
  • 通讯作者: 江大勇, E-mail: djiang(at)
  • 基金资助:
    国家自然科学基金(40920124002, 41920104001)、高等学校博士学科点专项科研基金(20120001110072)、安徽省自然资源厅科技项目(2021-k-13)和安徽省公益性地质工作项目(2021-g-2-16)资助


A specimen of Chaohusaurus brevifemoralis (GMPKU-P-3086) from the Lower Triassic in Chaohu City, Anhui Province is examined by using high-resolution CT scan data to create a 3D reconstruction. The reconstructed models include models of teeth, premaxilla, maxilla, and dentary. Through observation and measurement of the model, and comparison with the specimen, the following new features of this basal ichthyosauriformes were found. 1) the implantation is subthecodont based on the presence of a dental groove with shallow sockets at the bottom. 2) the sizes and shapes of the teeth vary periodically and appear as an odd-even alternate pattern. 3) the anterior teeth form a single row, with the replacement tooth setting on the distal position of the functional tooth. 4) Two rows of teeth at the distal parts of the dentary and maxilla are firstly found in Chaohusaurus. The lingual row comprises replacement teeth for the labial row, and each replacement tooth lies disto-lingual of its predecessor. These dental features found in Chaohusaurus brevifemoralis are consistent to that of the Early Triassic ichthyosauriformes, such as Grippia and Utatsusaurus, which might represent a primitive condition of the dental character of ichthyosauriformes and reflect a broad geographical distribution of crunch feeding guild.

Key words: Chaohusaurus brevifemoralis, Early Triassic, tooth replacement, CT scanning


对产自安徽省巢湖市马家山剖面下三叠统奥伦尼克阶斯帕斯亚阶南陵湖组上段的短腿巢湖龙标本(GMPKU-P-3086)进行研究, 根据 CT扫描数据重建牙齿及前颌骨、上颌骨和齿骨的三维模型。通过对模型进行观察和度量, 并与实际标本进行对比, 发现以下短腿巢湖龙牙齿新的特征: 1) 颌骨上存在连续的牙槽沟, 且内具浅的牙槽窝, 牙齿为亚槽生齿; 2) 牙齿的大小和形状呈周期性变化, 显示奇偶相间的交替模式; 3) 口腔前部发育单牙列, 替换齿位于功能齿的远中位置; 4) 口腔后部发育双牙列, 替换齿列位于功能齿的舌侧–远中位置。短腿巢湖龙的牙齿特征与早三叠世基干鱼龙类短尾鱼龙和歌津鱼龙具有一致性, 可能代表鱼龙类牙齿的原始特征, 并反映捕压式食性群团地理分布的广泛性。

关键词: 短腿巢湖龙, 早三叠世, 牙齿替换, CT扫描