David Wentz
David Wentz with his recent discovery — proposed to be a tooth of the giant shark megalodon.

From about 16 million to 2 million years ago, the giant shark megalodon dominated the seas as the largest marine predator to ever live. Despite being extinct for millennia, the megalodon caused a stir in southeast Michigan last August when 15-year-old Port Huron resident David Wentz discovered a fossilized tooth in the St. Clair River.

"I snorkel all the time out by the Blue Water Bridge," he said, referring to the bridge over the St. Clair River that joins Port Huron with Sarnia, Ontario.

Accompanied by his brother Shaun, 21, Wentz was swimming over the sandy river bottom when a smooth, gray stone caught his eye.

"It was kind of rock colored, but there weren’t any rocks around it or anything," said Wentz.

When he presented the find to his family, Wentz’s father Craig noticed its similarities to fossilized shark teeth presented on programs like those on the Discovery Channel’s "Shark Week."

Wentz said that their whole family enjoys educational television. "We watch a lot of National Geographic and stuff like that around here," he explained.

Sometimes referred to as the "megatooth" or "megamouth" shark, the megalodon is thought to have grown to lengths of up to 60 feet (18 meters), or three times as long as its most famous modern relative, the great white shark. In order to maintain its massive body, the megalodon consumed 1,500 pounds of fish, whales and other sharks each day.

The megalodon’s skeleton was made of soft, flexible cartilage. Because cartilage is usually broken down before it can be fossilized, megalodon fossils consist primarily of lost teeth that fell to the ocean floor like the one found by Wentz.

Even so, these tooth fossils provide insight into the nature of the prehistoric fish. For instance, the megalodon is often portrayed as a giant version of the great white, but growing evidence obtained by comparing tooth shape indicates that its nearest extant relative is the less well-known mako shark.

Though the Great Lakes region was once covered by shallow tropical seas, it is unlikely the shark whose tooth was found by Wentz was a prehistoric Michigan resident. Michigan State University paleontologist Dr. Michael Gottfried told the Port Huron Times Herald that it’s more likely that the fossil was brought to its location with the help of humans in relatively recent history.

For now, Wentz isn’t sure what he will do with the fossil.

"It’s really cool just to have and show to people, but I wonder if it might be worth something," he said. "I might sell it someday."