C. Megalodon was believed to have reached lengths of up to 50 feet (15m).

According to the Discovery News article, Prehistoric Shark Nursery Spawned Giants, paleontologists have discovered what is believed to be a breeding ground for the prehistoric shark known as C. megalodon (you can argue amongst yourselves about whether it is Carcharodon megalodon or Charcharocles megalodon). According to the article, researchers have found a "stash" of C. megalodon teeth measuring between 0.5 inches and 3 inches (1.3-7.6cm). Adult teeth from the species can measure up to 6 inches (15cm). Researcher, Catalina Pimiento (Univ. of Fla.), has determined the teeth to belong almost exclusively to juveniles of the species, based on comparisons with other fossilized adult teeth. The find in Panama is only the second of its kind to be discovered. Another cache of juvenile C. megalodon teeth was discovered in South Carolina, although in the case of that site adult teeth as well as whale skulls were also discovered. The Panama site appears to be the first site discovered exclusively with juvenile shark teeth, indicating that the area might have served as a "shark nursery," a habitat that would have enabled juvenile sharks to reach maturity with minimized predatory threats. According to Pimiento…

"These areas are and have been essential habitats for sharks’ survival, and without them the animals would not be able to succeed. Now they are typically coastal zones where humans overfish and construct. So what this study is telling us is that these areas have been used by sharks for millions of years, and we need to preserve them so sharks can successfully reproduce and survive."