FischerProductions has recently posted the above video, in which Dr. Michael Domeier disputes the theory that great white sharks (Carcharodon carcharias) descended from the prehistoric C. megalodon. Domeier says that the latest theory is that white sharks likely descended from mako sharks (genus Isurus).
It is noted that mako sharks were originally ruled out as descendants of white sharks due to modern mako sharks having non-serrated, smooth teeth. The discovery of serrations on the teeth of prehistoric mako sharks brought them into consideration as descendants of white sharks, but it is not specifically explained how this ruled out the C. megalodon as a potential descendant of the white shark.
A more detailed comparison of the two schools of thought on C. megalodon can be found at ElsmoResearch’s Carcharodon versus Carcharocles:
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