The Shark in the Backyard

Md. family uncovers 15-million-year-old shark skeleton during backyard dig

Donald Gibson found the first vertebra Oct. 23, just as he had begun to dig out the space for the sunroom he had promised to build in the back yard of his parents’ home in Calvert County.

Over the following week, his brother Shawn found another vertebra, and then another, and then a few more — each one about 18 inches deep into the ground. Soon, Shawn Gibson’s 7-year-old, Caleb, joined in on the digging. He’s at an age of being “thrilled to go out and not just play in the dirt, but actually find pieces,” Gibson said of his son.

After all, it’s not that unusual to dig up fossils in the Calvert Cliffs neighborhood. But then they found something more: a straight column of vertebrae, two feet long. And at the end, a tooth.

The digging stopped.

What the Gibsons unearthed were the remains of a 15-million-year-old snaggletooth shark, which paleontologists say is more complete than any other fossil of its kind in the world.

Stephen Godfrey, curator of paleontology for the Calvert Marine Museum, said that the Gibsons’ discovery is so unusual because of the number of bones they found — more than 80 vertebrae and hundreds of teeth, all from the same shark — as well as the position they were in and their unusually good preservation.

Snaggletooth upper tooth

Snaggletooth shark's teeth are one of our most common large sharks tooth fossils. Not as big as the much rarer Megalodon and Mako shark's teeth, they are especially distinctive because of the hooked, heavily serrated upper teeth, and the smooth, spear-like lower teeth. I think of them as knives and forks.

Snaggletooth lower tooth

Donald Gibson said he had pulled vertebrae out of the ground, one by one in a straight line, just as they were positioned in the back of the shark, which Godfrey said was 8 to 10 feet long during its life.

Just a baby!

Having preserved the teeth and surrounding remnants of cartilage in exactly the positions they were found in, the paleontologists will be able to take CT scans of the cast and analyze the specific three-dimensional layout of the prehistoric shark’s mouth, something scientists have never done.

“For the first time, we’re going to be able to know what the dentition — what the teeth — looked like in this kind of shark,” Godfrey said.

I think that's kind of an exaggeration. We have lots of Snaggletooth fossil teeth, and a close living relative in the Indo-Pacific to tell us how how they are likely put together. You can see one construction of a Snaggletooth dentition here.

I'm not likely to be finding Miocene shark fossil in my backyard anytime soon. At 100 ft above sea level, one of the highest areas in the county, the shark fossil bearing layers are pretty far underground here. I'm more likely to find an odd arrowhead or even a Gomptherium tooth or bone from later inhabitants after the area had emerged above the ocean.