Sharks as long as cars once roamed the ocean

American scientists have discovered a species of shark as big as a car with sharp teeth that lived commonly along the Atlantic and Pacific coasts 20 million years ago.

The shark Megalolamna paradoxodon lived 20 million years ago. Illustration photo: Wikimedia Commons.

The team found five 4.5-centimeter-long teeth of the extinct shark species in Japan, Peru and the United States (California and North Carolina), according to Live Science. The discovery was published yesterday in the journal Historical Biology.

"The fact that a shark of this size has such a wide geographic distribution shows how little we know about Earth's ancient marine ecosystems," said Kenshu Shimada, a paleontologist at DePaul University in Chicago and lead author of the study.

Researchers named the shark that lived during the early Miocene period Megalolamna paradoxodon, based on its large teeth that closely resembled those of sharks in the genus Lamna.

"At first glance, the teeth of Megalolamna paradoxodon resemble the giant teeth of the Lamna family, which includes modern mackerel and salmon sharks. However, these fossil teeth are too large for Lamna, reminiscent of the dental features of Otodus. Therefore, we determined this to be a new species belonging to the Otodontidae family and not directly related to Lamna," Shimada said.

Fossil teeth of Megalolamna paradoxodon have been found in many places around the world. Photo: Kenshu Shimada.

M. paradoxodon had snapping teeth in the front of its mouth, and tearing teeth in the back, Shimada said, allowing the animal to break up its prey. It likely lived in shallow coastal waters in the mid-latitudes, where the team found the fossilized teeth. Although they only dug up tooth specimens, they were able to estimate the shark’s length by comparing them to teeth from modern sharks.

By analyzing the tooth-to-body ratios of M. paradoxodon's modern relatives, including sandbar sharks, mako sharks, and great white sharks, the team estimated that it could have grown up to 3.7 meters (12.5 feet) long, about the size of a car.

Figuring out exactly how big M. paradoxodon was, however, is not easy, says John-Paul Hodnett, a shark expert and graduate student in biology at Saint Joseph’s University in Philadelphia, who was not involved in the study. Some modern sharks have small teeth but can grow to be more than 40 feet long.

The prehistoric teeth also helped researchers discover that M. paradoxodon was closely related to Carcharocles megalodon, the largest shark that ever lived on Earth. C. megalodon was 18 meters long and had a bite force stronger than that of the Tyrannosaurus rex. Both sharks belonged to the extinct Otodontidae family.

According to VNE