An oceanic whitetip shark and a mako shark appear to have followed this trail, winding up in more shallow water used for human recreation. Without sheep or other prey to eat, the sharks went after humans.
"So it's highly unusual for an individual shark or other animal to repeatedly prey upon humans, but it can happen," Burgess said.
Such encounters remind that humans were not always at the top of the food chain.
Kirsten Jenkins, a University of Minnesota anthropologist, explained that an early ape called Proconsul -- thought to have been an ancestor to both modern humans and chimpanzees -- was good eats for numerous predators.
"I have observed multiple tooth pits and probable beak marks on these fossil primates, which are direct evidence for creodonts and raptors consuming these primates," Jenkins told Discovery News.
Earlier this year, remains of an enormous horned crocodile, Crocodylus thorbjarnarsoni, were found next to Australopithecus, a now-extinct human relative. Researchers suspect that the croc regularly dined on humans.