Researchers claim they've discovered a prehistoric "nursery" used by the gigantic sharks that once ruled the oceans.

It would be only the third fossil shark nursery on record and by far the oldest at about 24 million years.

Researchers claimed the nursery, in South Carolina in the US, was used by megatoothed shark species Carcharocles angustidens, a relative of the more famous megalodon, Live Science reported.

Co-researcher Robert Bossenecker from the Mace Brown Museum of Natural History, told the outlet the teeth findings at the site also forced a revised estimate of how big the giant predators could get.

Prehistoric shark sizes are calculated from teeth, with the previous largest Carcharocles angustidens topping out at 8.47 metres.

Researchers claimed these new finds had led them to extrapolate a top size of 8.85 metres – compared to an upper limit of about six metres for a modern great white shark.

The megalodon was even bigger, reaching up to 16 metres in length.

The team's research has not yet been peer reviewed but was presented at the online annual conference of the Society of Vertebrate Paleontology last week.

Shark nurseries are havens for baby and juvenile sharks who spend time there before growing large enough to dare the wider ocean.

Source: 9News https://www.9news.com.au/world/fossil-shark-nursery-found-south-carolina-megalodon-relative/f9cf5af8-6c08-49fa-ba3d-a5ad09c16c94