An international team of researchers has identified a new extinct species of sharks that are believed to exist about 20 million years ago.

Their discovery, described in a paper published in the journal Historical Biology, was based on handful of fossilized teeth, which measure about 1.8 inches tall, found in four different locations, including California and North Carolina in the United States.

"The fact that such a large lamniform shark with such a wide geographic distribution had evaded recognition until now indicates just how little we still know about the Earth's ancient marine ecosystem," said Kenshu Shimada, a paleobiologist at DePaul University and research associate at the Sternberg Museum in Kansas and lead author of the study, in a report from Fox News.

The new shark species, named Megalolamna paradoxodon, have about the same size as the modern-day great white shark, roughly 13 feet in length. Just like great white and mako sharks, Megalolamna paradoxodon belongs to the Lamniformes group. Specifically, the new shark species belong to Otodontidae, which contains the iconic extinct super predator 'megalodon' or the 'megatoothed' shark.

The researchers noted that certain dental features suggest the new extinct shark is an otodontid. However, the fossilized teeth look superficially like over-sized teeth of the modern-day salmon shark that belongs to the genus Lamna. Due to this, the researchers gave its genus name Megalolamna. The researchers named the new species as paradoxodon, which means paradoxical teeth. The reason behind its species name is due to the fact that the shark appears to emerge suddenly in the geologic record with a yet unresolved nearly 45-million-year gap from when Megalolamna possibly split from its closest relative Otodus.

"The inclusion of megatoothed sharks into Otodus would make the genus a much preferred complete lineage referred to as a 'monophyletic group' that is considered to be a next of kin to the new genus Megalolamna," explained Shimada in a statement.

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