"The enormous, extinct shark Megalodon probably doesn't make you think of parenting and playdates. But a growing body of evidence suggests that these massive marine predators nurtured their babies by raising them in nurseries, and scientists just added five potential Megalodon nurseries to the list." Source: Live Science.
Comment: The Megalodon could still be out there, I suppose. According to Wikipedia, this monster shark "inhabited a wide range of marine environments (i.e., shallow coastal waters, areas of coastal upwelling, swampy coastal lagoons, sandy littorals, and offshore deep water environments)," so I suppose it could have adapted to the high pressure and darkness of deep ocean trenches. The Mariana Trench is a popular location because it's still mostly unexplored.
This is all nonsense, though. The Megalodon not only exists, but it isn't hiding in some dark trench. This supposedly extinct shark still feeds in coastal waters and it apparently has a taste of chicks in bikinis. We know the Megalodon is still out there because we have video proof from China. I have no idea why marine biologists are ignoring this footage.