Ancient white sharks grow more slowly

The most complete fossil of an ancient great white shark was discovered in the dry desert of Peru, including parts of the spine and mouth with 222 teeth.

White sharks are the king of sharks today, with bodies over 20 feet long. But the evolutionary history of this animal is still not well understood. It seems that 4 million years ago, they grew a bit slower.

There are still gaps in knowledge of shark evolution because fossil shark fossils are extremely rare, unlike other fish species, their frames are formed from cartilage.

The researchers encountered a 4-million-year-old fossil in 1988 while examining the sediment of Pisco Formation in the desert region of southwestern Peru. This area of ​​sediment became famous because of many types of fossils of whales, birds and even sea sloths, Thalassocnus.

Usually, only single teeth of sharks are found in ancient sediments. In order to get an overall picture of the 'bite' of ancient sharks, scientists had to pair the individual teeth together using information from modern sharks. This new fossil, with its teeth in its natural position, is important because the shape of each tooth and the orientation of the teeth in the jaw helps determine the relationship of sharks to each other.

The specimen image appears in the magazine Vertebrate Paleontology, with the nose at the top of the picture and the spine at the bottom. (Photo: Dana J. Ehret)

Bruce MacFadden, one of the fossil research scientists at the Florida Museum of Natural History, said: 'With the incredible preservation of this Pisco Formation specimen, we have the unique opportunity to improve. knowledge of paleontology of white sharks and extinct relatives'.

Researchers believe that white sharks are descendants of shark king, 'megatooth sharks'. The largest, for example, Carcharocles megalodon, can be 60 feet long, with a jaw that can expand 9 feet (2.5 meters).

However, the new specimen shows the modern white shark that is associated with modern mako sharks - a smaller shark that almost eats fish - closer than the ancient giant shark.

Dana Ehret, a graduate student at the Florida Museum of Natural History and lead author of the study, published in Vertebrate Paleontology magazine: 'The completion of this specimen allows us to have a deep understanding. more about the relationship between white shark and mako shark '.

This new fossil specimen is 17 feet long, about the size of modern white sharks.

Because this specimen also contains part of the spine, scientists can determine if the shark died around 20 years old. The age determination is based on bright and dark bands on the spine, calcification along with age and reflects some seasonal temperature changes.

A modern white shark with a similar age may be larger, suggesting that the shark in the specimen grows at a slower rate.