A shark the size of a car swam and hunted fishes along the coastlines of ancient Atlantic and Pacific oceans during the early Miocene epoch about 20 million years ago. This marine predator is now extinct but its pointy teeth that researchers found in globally distributed areas hint that it once existed.
Scientists have described this new species of extinct shark following analysis of five of these creatures' teeth, which measured nearly 2 inches long each and were collected in California, North Carolina, Japan and Peru.
"The fact that such a large ...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 study researcher Kenshu Shimada, a paleobiologist at DePaul University in Chicago.
The new species known as Megalolamna paradoxodon, which was described in a new study published in the journal Historical Biology on Oct. 3, belongs to the family of sharks called Otodontidae. A famous member of this group is the megalodon, the largest shark that terrorized the oceans with powerful teeth measuring almost 7 inches.
Megalolamna paradoxodon, which lived in the same ancient oceans where megatoothed sharks inhabited, were characterized by grasping-type front teeth and cutting-type rear teeth, which suggest that these predators used to hunt relatively large prey such as medium-sized fishes.
"All specimens came from deposits in the mid-latitudinal zones representing shallow-water, shelf-type, coastal environments," the researchers wrote in their study. "Its dentition likely exhibited monognathic heterodonty suited for capturing and cutting relatively large prey (e.g. medium-sized fishes)."
Some of the species' dental features suggest of the ancient shark's otodontid link but its teeth also look superficially like the oversized teeth of the modern-day salmon shark which belongs to the genus Lamna. This is the reason why scientists created a new genus Megalolamna.
The shark's name "paradoxodon," or paradoxical teeth, is due to the fact that the species appears to have suddenly surfaced at a time in the geologic record when there is an unresolved gap of nearly 45 million years from when Megalolamna possibly split from its closest cousin Otodus.
Despite the fact that the Megalolamna paradoxodon was smaller than other members of the megatoothed lineage containing the megalodon, it was still an impressive shark with size comparable to that of the modern-day great white shark. Megalolamna paradoxodon could grow to about 13 feet in length while the great white shark can grow between 15 and 20 feet long.
