Hello! I’m Sharon, the new editor for GeoLifestyle. I’m a retired geologist and college professor, as well as an author. I’ve enjoyed reading this newsletter since its inception (kudos to my predecessor, Cate Larsen) and am looking forward to sharing my own geo lifestyle with all of you!
One of my favorite summer activities is hunting for fossil shark teeth, so this week I’ll share my favorite spots to find these toothy treasures. Let’s dig in!
Prehistoric Bites
Miocene/Pliocene fossils, clockwise from the top: Shark Teeth, Turtle Shell, Stingray Grinding Plates, Crab Claws, Dolphin Tooth, Fish Vertebra, Whale Bone. Center: Ephiphysis vertebral growth plate from a dolphin. These are known as "cookies."
Why are we fascinated with sharks?
The simple answer is sharks are big and scary. Cue the music from Jaws or watch a scene from The Meg, and you’ll know what I mean.
In some cultures, sharks have symbolic meanings. In Hawaiian legends, guardian spirits can take the form of sharks, which are considered protectors and symbols of strength.
Sharks are interesting biologically. They use finely-tuned electroreception to locate prey and have up to 15 layers of teeth. These teeth continually shed throughout their lifetimes. One shark can grow up to 50,000 teeth.
Long in the tooth: Sharks are chondrichthyans: cartilaginous fishes. Because cartilage doesn’t preserve well, fossil sharks are identified by their teeth and skin scales, known as dermal denticles.
The oldest shark fossils:
The first shark-like fossils are from after the Great Ordovician Biodiversification Event about 450 million years ago.
The oldest named shark comes from the middle Ordovician Stairway Sandstone in central Australia. Jawed fish were still developing at this time, so the first sharks may have been jawless and toothless!
The best-preserved specimens of complete early sharks are from the late Devonian Cleveland Shale, near Lake Erie in Ohio. These species looked more like fish than today’s sharks. Some lived in freshwater.
What do shark fossils tell us about shark evolution?
When placoderms (armored fish) became extinct at the end of the Devonian, sharks filled the vacant ecological niches. The Carboniferous became known as the Golden Age of Sharks.
After barely surviving the Permian extinction event, sharks were eclipsed in the Mesozoic by the dominant marine reptiles. They diversified into eight shark orders.
When the K/Pg mass extinction event killed off marine reptiles and nonavian dinosaurs, sharks became the top ocean predators in the Cenozoic, feasting on newly evolved marine mammals.
What about giant sharks?
Sharks evolved to giant sizes in the Cenozoic, including the gigantic Otodus megalodon in the Miocene epoch.
A Meg could reach 59 feet in length and weigh up to 48 tons, three times the size of a great white shark.
Megalodons went extinct at the end of the Pliocene, except in Hollywood where they live “beneath the thermocline.” (Bring on the groaning, all ye marine scientists).
You can learn more about the progression of shark fossils here.
Where to Find These Toothy Time Capsules?
Handmade sieve used in fossil hunting/ Courtesy of Sharon Lyon
Most of my fossil hunting has been in Maryland and Virginia, but there are tons of locales to explore worldwide!
In Maryland, Miocene fossils occur within the Calvert, Choptank, and St. Mary’s Formations (20–10 million years old) from the cliffs along Chesapeake Bay. In Virginia, Pliocene fossils occur within the Yorktown Formation (5–2.5 million years old).
Maryland fossil hunting hubs:
Calvert Cliffs State Park: From the parking area, it is an easy walk to the beach where collecting is allowed.
Flag Ponds Nature Park: Park at the small visitors’ cabin, where you can view examples of fossils, then meander down the nature walk to the beach. The nearby cliffs belong to a nuclear power plant.
Matoaka Beach Cottages: These cabins are privately owned and charge a fee for day hunting or to rent for an extended stay.
Virginia fossil hunting hubs:
Westmoreland State Park: Visit the nature center, then hike the easy 0.6-mile Fossil Beach trail to the Potomac River.
Stratford Hall: Start at the visitor center to learn about Virginia history and get a map for beach parking.
Chippokes Plantation State Park: Fossils here are from the Pliocene Yorktown Formation, along the James River. Shells are aplenty, but shark teeth require a sharp eye.
York River State Park: A Fossil Beach sign directs you during a short walk. The park’s brochure requests you take one fossil per person, so four of us brought home one shark tooth, one fish vertebra, one crab claw, and one sting ray tooth. Part of the shoreline has been stabilized recently to limit erosion (good for the shoreline, bad for fossil hunting).
What to look for:
Walk the shoreline and the high tide line and look at anything black or brown in color. Check the outflow areas of any creeks.
You can also find other Miocene/Pliocene fossils, such as stingray teeth, fish bones, whale bone, turtle shell, crocodile teeth, crab claws, and porpoise teeth—not to mention a collection of bivalves and gastropods.
Remember: Follow all posted signs, only collect on beaches and not in cliffs, check tide charts, and pay all fees (be a good geo-citizen!)
Must-See Museum: The Calvert Marine Museum
Examine the vast array of fossils discovered in Calvert Cliffs at the Calvert Marine Museum in Solomons, Maryland. Watch a geo-animation video about the area and take a selfie with a 35-foot restoration of a Megalodon. Be sure to ask about the museum’s paleo prep lab.
I’ve found this book immensely helpful for identifying my beach finds. Each fossil is photographed from different angles, with concise information, including taxonomy.
Do you have a favorite fossil collecting site? Let me know at editorial@aapg.org. I hope you enjoyed my maiden voyage with the GeoLifestyle newsletter. Happy fossil hunting! See you next week!
Sharon Lyon
Editor, GeoLifestyle
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