Historically, mapmaking was a fairly imprecise task . . .to fill blank areas on the maps, mapmakers used to include textual/graphic warnings of the dangers of going into uncharted territory. Such warnings took the form of sea serpents, dragons, mythical and, sometimes, even real creatures. The actual line "Here There Be Dragons" has been found only once, on the 16th-century Lenox Globe — but is too cool to give up.
The frill shark has a large mouth with 25 rows of 300 sharp teeth, six pairs of fringed gill slits, and a long, eel-like body that can grow up to 6 feet long. It's referred to as a "living fossil" because it's a member of one of the oldest living shark species.
The Miocene epoch (23.03 to 5.332 million years ago) boasted a real life sea monster, Carcharocles megalodon. Whereas the giant shark mainly inhabited the open ocean, this image depicts a hypothetical encounter with a swimming Platybelodon, a prehistoric mammal related to the elephant. The bones of these elephantids sometimes show evidence of attack by sharks.