Reconstructing Carcharodon: A historical, taxonomic, and evolutionary synthesis from the eighteenth century to the present

The evolutionary history of Carcharodon is characterized by persistent taxonomic uncertainty, extensive historical nomenclatural change, and an incomplete fossil record dominated by isolated teeth. Here, we reconstruct the historical, taxonomic, geographic, and evolutionary history of the genus from pre-Linnaean accounts of the white shark to the present, integrating original nomenclatural treatments, subsequent generic combinations and synonymies, dental morphology, geological age, and geographic occurrence. Particular attention is given to the broad-toothed fossil complex historically associated with Carcharodon hastalis, including the plicatilis and xiphodon concepts, and to Carcharodon hubbelli, the Late Miocene taxon proposed as a morphological intermediate between broad-toothed forms and C. carcharias. We evaluate three competing evolutionary models: a predominantly linear transformation, a branched history involving multiple contemporaneous or geographically differentiated lineages, and a mosaic model in which dental characters, temporal occurrence, and geographic distribution underwent partially independent transformations. The reconstruction supports a broadly directional morphological transition from non-serrated Carcharodon-grade forms toward the fully serrated dentition of C. carcharias, with C. hubbelli providing particularly strong evidence for a transitional character combination. However, chronological succession is not considered sufficient evidence of direct ancestry, and the uncertain relationships among hastalis, plicatilis, xiphodon, and other broad-toothed forms indicate that the evolutionary history may have involved a more complex radiation than a simple ancestor–descendant sequence. The emergence of the modern C. carcharias phenotype occurred around the Miocene–Pliocene transition and was followed by broad Pliocene geographic expansion, Pleistocene redistribution and persistence, and continued Holocene and historical occurrence. We conclude that the history of Carcharodon is best understood as a directional evolutionary transformation expressed through morphological mosaicism and geographic restructuring, rather than as a strictly linear succession of named fossil species.