The World’s Oldest Shark Nursery

Sharks have long been known as an ancient form of marine life. But it is difficult to find much information about the oldest sharks since they have few bones. Ordinarily, the only evidence they usually leave behind are a few teeth. Then researchers working at a site in southwestern Kyrgyzstan discovered evidence of what is currently the world’s oldest shark nursery. One of the surprises is that these sharks were born in a shallow freshwater lake around 230 million years ago.

Researchers recovered about 60 tiny teeth belonging to baby sharks called hybodontids, along with fossilized egg capsules. Some experts believe that the sharks spawned in fresh water after traveling upriver from the ocean in the same way that modern salmon return to freshwater rivers after spending most of their lives at sea.

Study leader Jan Fischer of the Geologisches Institute at TU Bergakademie Freiberg in Germany, has suggested the possibility that these sharks spent their entire lives in lakes and rivers. He believes that the distance ocean-dwelling sharks would have had to travel upriver makes the idea of spawning migrations from the ocean improbable.

There are more than 400 species of sharks in the world today. Nearly all of them live in oceans. But there are five species of freshwater sharks living in rivers and lakes in Australia, New Guinea, various locations in Southeast Asia, and India. They are rare and not much is known about them. Some can grow to around 9 feet (3 meters) in length, although very few large sharks have been found. Unfortunately, all five species are currently endangered due to pollution, fishing, and other human-caused circumstances.

For more information on the Triassic-era shark fossils, visit here

For more information about modern freshwater sharks, go here