Megalodon , meaning "big tooth", from Ancient Greek: μέγας (megas) "big, mighty" and ὀδoύς (odoús), "tooth"—whose stem is odont-, as seen in the genitive case form ὀδόντος, odóntos)[1] is an extinct species of shark that lived approximately 23 to 2.6 million years ago, during the Cenozoic Era (early Miocene[2] to end of Pliocene[3]).

The taxonomic assignment of C. megalodon has been debated for nearly a century, and is still under dispute. The two major interpretations are Carcharodon megalodon (under family Lamnidae) or Carcharocles megalodon (under the family Otodontidae).[4] Consequently, the scientific name of this species is commonly abbreviated C. megalodon in the literature.