Sharks: From Miocene to Modern Day

Meg Tooth - Anjelica Eitel - 1171x593

Megalodon’s name means “big tooth,” and that’s no exaggeration. Teeth like this one, measuring 4.5”, have been found along the shores of the Chesapeake Bay. It is currently on display at the Calvert Marine Museum.

Anjelica Eitel/CBF Staff

Taking a bite into the history of sharks in the Bay

We’ve all heard about sharks in the Bay, but did you know that these apex predators have actually been living here long before us humans ever showed up? 

Megalodon (Otodus megalodon), the world’s largest ocean predator, called the Chesapeake Bay region home millions of years ago—20-7 million years ago to be precise. Its name “megalodon” means “big tooth,” and that’s no exaggeration. Megs were estimated to have been up to 65 feet long and we still find their fossilized teeth, which are sometimes as large as 6 inches, along local beaches.

So what made the Bay region an ideal habitat for this Miocene monster? And what can those early days of sharks in the Chesapeake teach us about their modern-day cousins? I headed to my old stomping grounds at the Calvert Marine Museum (CMM) in Solomons, Maryland, to find out.

My first stops at CMM, which also doubles as the Maryland Center for Paleontology Collections and Research, were with Dr. Stephen Godfrey and Dr. Victor Perez. If you’re looking to talk shop about the shark fossils found along Calvert Cliffs, there’s no better place to start.

As I walked into their offices, it felt like I had stepped into a museum within the museum. There were shark teeth and reconstructed jaws everywhere I looked.  

Dr. Perez, who has studied sharks from the Chesapeake to Central America, explained that the Bay as we know it didn’t really exist 10 million years ago. Maryland’s entire Eastern Shore was completely submerged and sharks like megalodon inhabited waters that flooded over the Atlantic Coastal Plain. These sharks were believed to have roamed the globe, following food sources to ideal hunting grounds. Can you imagine a world so different?

Not only did megalodons change their location—over the 15+ million years they inhabited Earth, these massive creatures adapted in a number of ways. Megalodon was the final stage of evolution in a lineage of sharks called the megatooth sharks. One of megalodon’s early ancestors, named Otodus obliquus, lived around 60 million years ago. This early ancestor had teeth that were quite different from megalodon. Otodus obliquus had teeth that were narrow, with non-serrated cutting edges. These teeth were ideal for puncturing their prey and eating it whole. However, over time, megatooth sharks adapted wider teeth, with serrated edges, to feed on new prey—whales and dolphins. This simple, yet significant, adaptation shows us that even those at the top of the food chain need to evolve in an ever-changing environment if they are to survive. As Dr. Godfrey put it, “it doesn’t matter how big and powerful you are. If you can’t adapt to a changing environment, then you’ll become extinct. But the neat thing about life is that there’s this thing called evolution, and evolution is the antidote to extinction.”

A large shark tooth cuts into a fossilized vetebra that is held in someone's hand

Fossils like this dolphin vertebra with teeth marks help scientists determine what ancient sharks may have been feeding on. These specimens are on display at Calvert Marine Museum.

Anjelica Eitel/CBF Staff


Eventually, as with many creatures, megalodon’s evolution was unable to keep up. While there are several theories as to why these sharks became extinct, a popular one is that their prey—in this case, ancient whales—evolved more quickly and became exceedingly difficult targets for the meg. In the end, it may have been the shark’s highly specialized hunting practice and choice of prey that led to its downfall.

As they say, the more things change, the more they stay the same. We see similar adaptations with the sharks of today. Changes in water temperature and salinity content determine whether we see more or less sharks in Bay waters. This could mean that as we see warmer temperatures and slight increases in salinity due to climate change, shark sightings may become a more regular occurrence. CMM estuarine biologists Perry Hampton and Linda Hanna shared that there are already approximately a dozen different species of sharks found in the Chesapeake. Many of these inhabit the lower Bay, where salinity content is higher thanks to a closer proximity to the ocean. Some of the most commons types you’ll see are smooth dogfish (Mustelus canis), spiny dogfish (Squalus acanthias), and sand tiger sharks (Carcharias taurus). Sandbar sharks (Carcharhinus plumbeus) also spend much of their time in the lower Bay, and females even use the area as a nursery for their pups. In Maryland’s Bay waters, you won’t see nearly as many species—again, due to that salinity content. The one notable exception is the bull shark (Carcharhinus leucas). This species can range from 7 to 11.5 feet in length and weigh between 200 and 500 pounds, and they are known for tolerating environments with more freshwater. They’re also fans of warmer temperatures, so as waters become hotter, there’s a chance that we could see more sharks in areas like Southern Maryland

A thin, gray spiny dogfish lays slightly curled on the sand beneath the water

Spiny dogfish are commonly found in the lower Bay south of the Potomac River. Males will grow just over 3 feet long, and females can reach 4 feet in length.

Rick Starr/NOAA CBNMS


Something to keep in mind, however, is that the presence of apex predators is almost always a good thing. When we find creatures like sharks and dolphins in the Bay, it means that the ecosystem is healthy enough to support a robust prey population. For example, bull sharks enjoy snacking on cownose rays, which eat oysters and clams, which rely on plankton to survive. While the thought of sharks sharing the Bay can seem frightening, it’s a sign that nature is balancing itself out.  

But for now, how can us fin fans appreciate the sharks of yore? A few months back, we shared a nature journaling blog about proggin’—also known as beachcombing. In addition to sea glass and shells, we can find fossil treasures along many of the beaches that line the Bay. One of my favorite spots growing up was Brownies Beach, which is officially known as Bayfront Park, in Chesapeake Beach. Here, even the amateur fossil hunter can find dozens of shark teeth in an hour or so. This site is currently closed to the public, but keep it on your list for next summer. It’s worth the wait! 

If you travel a little farther south along Calvert Cliffs, Flag Ponds Nature Park and Matoaka Beach Cabins are both great spots to enjoy the Bay and unearth ancient treasures. Head over to Charles County and you’ll find Nanjemoy Wildlife Management Area, formerly known as Purse State Park, a 217-acre site with beach access and even more spots for diving into the past. It is important to note that whenever exploring along any of these formations, you must have permission to be there and never dig into cliffs. As long as you’re following the proper protocols, enjoy the beach and happy hunting!

A collection of gray, black, and tan shark teeth with a larger tooth laying on top

Shark teeth of all shapes and sizes are still waiting to be discovered. You just need to know where to look!

Anjelica Eitel/CBF Staff

Want to learn more? Check out these helpful resources:

Anjelica-Eitel-Headshot_90x110

Anjelica Eitel

Digital Engagement and Social Media Manager, CBF

AEitel@cbf.org

Issues in this Post




Disclaimer

The views and opinions expressed in the media or articles on this site are those of the speakers or authors and do not necessarily reflect the views and opinions held by CBF and the inclusion of such information does not imply endorsement by CBF. CBF is not responsible for the contents of any linked Website, or any link contained in a linked Website, or any changes or updates to such Websites. The inclusion of any link is provided only for information purposes.


The Bay Needs You

The 2020 State of the Bay Report makes it clear that the Bay needs our support now more than ever. Your donation helps the Chesapeake Bay Foundation maintain our momentum toward a restored Bay, rivers, and streams for today and generations to come.

Donate Today

Save the Bay

Founded in 1967, the Chesapeake Bay Foundation (CBF) is the largest independent conservation organization dedicated solely to saving the Bay.

Save the Bay
x
This website uses cookies to tailor and enhance your online experience. By continuing, you are agreeing to our use of cookies. For more information, including details on how to disable cookies, please visit our Privacy Policy. Close