Just 1.5 million years before humans began taking leisurely dips in the ocean, the waters were home to an immense shark "Megalodon" (formally known as Carcharocles megalodon). Despite coming in at more than 60 feet long, young C. megalodons would still have been vulnerable to other predators of their time, much like young great whites are today. According to a new study published in PLoS One the "mega-toothed shark" may have protected its young by delivering them in nurseries.

"Over the years paleontologists have identified several sites relatively rich in juvenile C. megalodon teeth, including the 10 million year old (Miocene) Gatún Formation of Panama. The marine fossil site preserves a shallow habitat containing numerous C. megalodon teeth and a relative paucity of whale bones (prey for adult sharks that their young probably would not have fed on), and for the first time a team of paleontologists have tested the idea that his place was once a haven for the young predators."

Learn more about these prehistoric shark nurseries.