Xinhua news agency, Beijing, August 28 (reporters Jindi and Dong Ruifeng) - the reporter learned from the Institute of Paleovertebrates and Paleoanthropology of the Chinese Academy of Sciences that China has discovered the fossil of the marine killer valve toothed shark 290 million years ago for the first time. This expands the paleogeographic distribution of the valve toothed shark in the northern hemisphere, provides important evidence for the migration of this prehistoric giant shark across the ocean, and reveals that the valve toothed shark may be a top predator with strong swimming ability. The relevant results have recently been published as a cover article in the International Journal Journal Journal of Geology (English version).

Ecological restoration map of Shanxi Yangquan valve toothed shark 290 million years ago (painted by Yang Dinghua).

Gai Zhikun, associate researcher of the Institute of ancient vertebrae of the Chinese Academy of Sciences, introduced that the valve toothed shark is a very mysterious and primitive fish. It mainly lives between 360 million and 250 million years ago. In classification, it belongs to the true soft bone class of cartilaginous fish, which means “fish with real cartilaginous head”. At present, there are only 17 genera and species of valved toothed sharks described, and most of them are scattered tooth fossils.

According to reports, a total of 7 petal toothed shark tooth fossils were found in Yangquan area, Shanxi Province. After comparative study, it was determined as Ohio petal toothed shark in the genus of petal toothed shark of the family petal toothed shark. Abundant marine fossil evidence shows that more than 200 million years ago, Yangquan was a warm and transparent shallow sea close to the equator, which was suitable for the survival of all kinds of marine organisms.

Lin Xianghong, a researcher at the Institute of ancient vertebrae of the Chinese Academy of Sciences who participated in the study, told reporters that in terms of size, the size of the fossil teeth of the valve toothed shark found this time is similar to that of the living great white shark. It can be speculated that it is a kind of prehistoric giant shark with a body length of 3 to 5 meters, “The scattered state of fossil preservation also shows that the petal toothed shark, like most sharks today, may replace its teeth for life.” At present, the fossils of valve toothed shark have been found in many areas of the northern hemisphere, but it has not been found in the southern hemisphere.

Petal toothed shark tooth fossils (taken on August 27, mobile phone photo).

How did the petal toothed Shark Live and prey in the ocean hundreds of millions of years ago? According to Lin Xianghong, the traditional view is that they are benthic shell eating fish with slow movement, and feed on benthic crustaceans such as brachiopods and bivalves. However, this study found that the horizontal imbricate ridge band around the base of the tooth crown of the valve toothed shark may have the function of increasing friction to prevent prey from escaping when the teeth pierce the muscle and soft tissue.

This suggests that the petal toothed shark may be similar to the living great white shark and is the top predator in the Paleozoic ocean. The discovery of petal toothed shark fossils in China and Japan outside Europe and America shows that it has the ability to migrate across the ocean and may be a kind of predator with strong swimming ability.