Data from: A peculiar tooth renewal in a Jurassic ray-finned fish (Lepisosteiformes: †Scheenstia sp.)

Tooth replacement in vertebrates is extremely diverse, and its study in extinct taxa gives insights into the evolution of the different dental renewal modes. Based on µ-CT scans of a left lower jaw of the extinct fish †Scheenstia (Actinopterygii – Lepisosteiformes), we describe in detail a peculiar tooth replacement mode that is, as far as we could trace back in the literature, unique among vertebrates. The formation of the replacement teeth comprises a 180° rotation of their acrodin cap that occurs intraosseously within bony crypts, and their setting up appears to be synchronous. We propose a model for the dental renewal process, and identify complementary anatomical features visible in the tomography such as the junction between the different tooth-bearing bones (prearticular-coronoid and dentary), as well as cavities corresponding to intraosseous crypts, nervous and/or vascular canals. The location of the cavities and their subsequent identification (e.g. Meckel’s cavity, mandibular sensory canal) help settling the function of pores visible on the bone surface and understanding their relation to internal anatomical features. Finally, this tooth replacement mode raises the question whether it is specific to †Scheenstia or rather related to a particular dentition type and thus potentially occurs in other lineages.

脊椎动物的牙齿替换模式极具多样性，针对已灭绝类群的相关研究可为不同牙齿更新模式的演化历程提供关键见解。本研究基于已灭绝辐鳍鱼纲（Actinopterygii）雀鳝目（Lepisosteiformes）Scheenstia属（†Scheenstia）的左下颌骨显微CT（µ-CT）扫描数据，详细描述了一种特殊的牙齿替换模式——就目前可追溯的文献范围而言，该模式在脊椎动物中独一无二。替换齿的形成过程包含其齿尖帽（acrodin cap）在骨隐窝（bony crypts）内发生的180°骨内旋转，且替换齿的就位过程似乎具有同步性。本研究提出了一套牙齿更新过程的模型，并识别出断层扫描图像中可见的补充解剖学特征，例如不同承载牙齿的骨骼——前关节骨-冠状骨（prearticular-coronoid）与齿骨（dentary）——之间的连接结构，以及对应骨内隐窝、神经和/或血管管道的空腔。这些空腔的位置及其后续鉴定（例如梅克尔腔（Meckel’s cavity）、下颌感觉管（mandibular sensory canal）），有助于明确骨表面可见孔隙的功能，并解析其与内部解剖结构的关联。最后，这种牙齿替换模式引出了一个核心问题：该模式究竟仅为已灭绝Scheenstia属所特有，还是与特定的齿列类型相关，从而可能存在于其他演化支系中？