The fossil of a type of shark with petal-shaped teeth, which dates back to 290 million years ago, has been found in China for the first time, expanding its paleogeographic distribution, according to Chinese researchers.

Seven well-preserved Petalodus teeth were discovered in the Qianshi limestone in Yangquan City, north China's Shanxi Province.

The research has been published in the English edition of the latest issue of Acta Geologica Sinica, journal of the Geological Society of China, and it showed that the specimens are characterized by petal-shaped teeth with a spade-like crown and a long, tongue-shaped root.

The shark with petal-shaped teeth is a very mysterious and primitive fish, mainly living between 360 million and 250 million years ago, said the first author of the study, Gai Zhikun, from the Institute of Vertebrate Paleontology and Paleoanthropology under the Chinese Academy of Sciences (CAS).

In terms of size, the shark's tooth fossil is similar to the tooth of the great white shark. It can be estimated that it is a prehistoric giant shark with a body length of three to five meters, says co-author Lin Xianghong, also from CAS.

So far, the fossil of the shark species has been found in multiple places in the Earth's Northern Hemisphere. Besides Europe and America, the shark's fossil has been found in China and Japan, indicating that it had the ability to migrate across the oceans and was probably a predator with strong swimming capabilities, according to the researchers.

Abundant fossil evidence shows that the city of Yangquan was a warm and transparent shallow sea near the equator more than 200 million years ago, suitable for all kinds of marine life to survive, said fellow co-author Bai Zhijun with the Planning and Natural Resources Bureau of Yangquan City.