Who’s your daddy? A scientific perspective into the evolution of great white sharks

by Becca Shelton, RJD Intern

There are few things I love more than sharks and a good debate. The white shark, or great white, (Carcharodon carcharias) is my favorite species of extant sharks and the megalodon shark (Carcharodon megalodon) is my favorite extinct species. It just so happens that both species are in the center of an interesting dispute. Who is the ancestor to the white shark? For a long time, I personally had no doubt it was the megalodon shark because of similar looking teeth and jaws. In reality, this is not an easy question to answer. One of the reasons is that the species of sharks that are theorized to be the “closest” ancestor are extinct. Since sharks possess a cartilaginous skeleton, there is almost never a fully preserved skeleton since cartilage does not preserve well, unlike animals with boney skeletons. However, shark teeth are covered in enamel which helps in preservation and fossilized shark teeth can be found all over the world. Most of the debates surrounding this white shark ancestry involve teeth, especially morphology and serration. The two major theories I will be discussing are the megalodon hypothesis (Carcharodon megalodon) and the hastalis hypothesis (Isurus hastalis).

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