Fig. 6

Diversity of the dentition, the tooth replacement, and the palatine tooth morphology inside the placodont phylogenetic tree. The ventral views of the different placodont skulls come from Crofts et al. [29] except for the Henodus chelyops skull that was modified from Mazin [24], and the P. atancensis skull that was modified from Miguel Chaves et al. [8]. The lingual and vertical tooth replacement representations were made by Rieppel [17]. The lingual tooth replacement is based on his observations on Nothosaurus (Eosauropterygia) and the vertical tooth replacement is based on Placodus gigas (Placodontia). The occlusal surface shapes were redrawn after Crofts [27, 28] and Crofts et al. [29]. The cladogram is based on the phylogenetic analysis from Wang et al. [16]