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. Photo illustration: Wikimedia Commons.

The team found five 4.5-centimeter-long teeth of the extinct shark 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 such a large shark 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 early Miocene shark Megalolamna paradoxodon, based on its large teeth that closely resemble 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 at the front of its mouth, and tearing teeth at the back, Shimada said, allowing the animal to dismember its prey. It likely lived in shallow coastal waters in the mid-latitudes, where the fossilized teeth were found. Although they only dug up tooth specimens, they were able to estimate the shark’s length by comparing them with 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 it could grow up to 3.7 meters long, about the size of a car.

Figuring out exactly how big M. paradoxodon was, however, isn’t easy, says John-Paul Hodnett, a shark expert and graduate student in biology at Saint Joseph’s University in Philadelphia, who wasn’t involved in the study. Some modern sharks have small teeth but can grow longer than 12 meters.

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 more powerful than that of a Tyrannosaurus rex. Both sharks belong to the extinct Otodontidae family.

According to VNE