A casual science fan has likely heard of the phenomenon that is Shark Week — a week of shark-themed shows aired on The Discovery Channel annually. Some avid shark fans have likely already been glued to their TVs this week, watching the premieres of movies such as “K-Pop Shark Hunters” and “Jurassic Sharks.”
What many science novices and shark enthusiasts alike may not know is that sharks have connections to the Natural State itself, going back millions of years.
“One of the biggest surprises for people is learning that sharks once swam where Arkansas highways and forests are today,” said Dr. René Shroat-Lewis, associate professor of geology at the University of Arkansas at Little Rock.
Sharks are over 400 million years old, making them older than dinosaurs. During the Late Cretaceous Period, about 100 to 66 million years ago, much of southern Arkansas was covered by a warm, shallow sea connected to the Gulf of Mexico. These waterways were home to dozens of species of sharks, and their fossilized teeth can be found all over the state today, especially in the southwest region of the state.
“Pangea was still breaking apart and moving North America and the Eurasian continent into their current positions, forming the Atlantic Ocean as it did so,” she said.
When Shroat-Lewis was hired at UA Little Rock, she began to learn more about the marine history in the state and would often go hunt for shark teeth near Malvern on the Ouachita River. More than 17 species of sharks and rays have been found in the Arkadelphia Marl near Malvern.
Dr. René Shroat-Lewis | Photo by BENJAMIN KRAIN
“I am often asked why we mostly find shark teeth and no other body parts,” Shroat-Lewis said. “The reason is because sharks have skeletons made of cartilage, the same flexible material that makes up our ears and noses. Cartilage doesn’t fossilize very well, so complete shark skeletons are extremely rare.”
Sharks also lose teeth continuously throughout their lives, meaning that they could shed over a thousand in their lifetime.
“The sharks may be gone, but every tooth they left behind is another clue to reconstructing Arkansas’ ancient oceans,” she said.
If you want to go hunting for shark teeth yourself, Shroat-Lewis recommends checking the Ouachita River near Malvern.
“The riverbed is generally dry in the mornings, which means you can walk around on the bed,” she said. “Gravity causes the teeth to fall out of the current and get stuck in the depressions and gravel bars.”
However, she warns that any novice archaeologists need to check when the Remmel Dam will be released each day.
“You want to be out of the dry riverbed long before that water comes surging down the river,” she said.
Dr. Sinéad Ní Chadhain, chair of the department of biology at the University of Arkansas at Little Rock, said there are only a few types of sharks that can survive in freshwater environments; the most common one is called the bull shark. They are highly adaptable sharks and often go where their food goes, which can take them to some strange places.
Dr. Sinéad Ní Chadhain |
Photo by Benjamin Krain
It is highly unlikely that a shark would be in any Arkansas water in modern day, but some sharks have been reported swimming far up the Mississippi River.
Even though you probably will not come in contact with a shark in water in Arkansas, it is still important to be aware of them when taking an out-of-state beach vacation or big ocean fishing trip.
“Any time you’re in the water, it’s their realm, not yours,” said Dr. Julie Prerost, science teacher at Parkview Arts and Science Magnet High School in Little Rock.
She also advises people who are fishing from boats that if they catch a shark, they should cut it loose. Do not try to pull it up onto the boat. That is where many shark injuries are common.
“It’s important to be aware,” Prerost said.
For example, if you find yourself swimming in the ocean and a large school of fish is around, you may not want to be in that area since those fish may attract a hungry shark.
Dr. Julie Prerost
In actuality, sharks get a “bad rap” and are not the blood thirsty monsters that movies may have us believe, Ní Chadhain said. Most sharks are slow-growing and never get as large as the Great Whites and Megalodons featured in a lot of nature documentaries. Ní Chadhain said that the two biggest sharks are actually filter feeders, meaning they strain water to get the plankton and krill in the water, so you won’t ever see them violently tearing any fish apart to have their dinner.
Even though sharks have captured human interest for a long time, and still do, as displayed by events like Shark Week, the interest is not mutual.
“They’re just not that interested in people,” Ní Chadhain said.
For people who want to keep learning about Arkansas history, Shroat-Lewis invites them to check out the new Museum of Natural History that is set to open soon on the UA Little Rock campus. It will be located on the fifth floor of the Ottenheimer Library. Tentatively, the first exhibit will be “Arkansas Through Time” and will feature fossils, rocks, meteorites and other modern biological materials.
