ELI5 Megalodon - how are we sure they are extinct?

How are scientists so sure that the Megalodon is extinct? Especially since I keep on hearing them say we’ve explored less than 5% of the earth’s deepest oceans? What did they look like? Where did they live? How did they become extinct? ... we explain like I'm five Thank you to the r/explainlikeimfive community and in particular the following users whose questions and comments formed the basis of this discussion: blackwolfeone, m8asonmiller, rawrthedinosawrr, tomalator, theworthing, ippus_21 and indigoindica_za To the ELI5 community that has supported us so far, thanks for all your feedback and comments. Join us on Twitter: https://www.twitter.com/eli5ThePodcast/ or send us an e-mail: [email protected]