This study describes tooth structure, development and replacement in the great white shark, Carcharodon carcharias. Microstructure of the osteodont condition, characteristic of Lamnidae, differs from the orthodont condition found in sharks such as Carcharhinidae. Osteodentine development in Carcharodon is described. Findings are applied to identify shark teeth recovered in an archeological investigation. Differences in development between so-called lateral cusplets in the teeth of Carcharodon and lateral cusplets of Lamna are described. These structures are not homologous and the so-called lateral cusplets of Carcharodon are interpreted as serrational cusplets. Use of dental characters in lamniform phylogeny is reviewed, and problems in character definition and coding from earlier analyses are identified. When those problems are corrected – and especially in view of the finding that serrational cusplets of Carcharodon are not homologous to lateral cusplets in other Lamniformes – I conclude that Lamna is the sister group to Isurus + Carcharodon.