Last month, geology professor Marty Becker and five students spent three days fossil hunting along the banks of Arkansas' Ouachita River. They weren't looking for dinosaur bones, but for sharks' teeth and other fossils from a prehistoric ocean that once covered much of the United States.
"It's one thing to see fossils in a textbook," Ben Daniels, junior physics major, said. "It's something else to pull one out of a stream. It makes it so much more real."
According to a popular scientific theory, a meteorite impacted the earth 65 million years ago, landing right off the Yucatan peninsula of Mexico and wiping out the dinosaurs. But the dinosaurs weren't the only animals that disappeared.
"Simultaneous with the dinosaurs going extinct, many species of shark went extinct," Becker said. "You had all these animals living together in this gigantic ocean, and then, 65 million years ago, that's the end. They're replaced by completely new species. From a geological perspective, the extinction appears almost instantaneously."
In his research, Becker studies sharks and related animals from the Cretaceous time period, approximately 65 to 80 million years ago.
The fossils in Arkansas are the subject of an upcoming paper in The Journal of Paleontology. This is Becker's fourth time visiting the site.
The Arkansas site was a previously undiscovered piece of the prehistoric coastline which reached from New Jersey to Texas and up to North Dakota. Shark fossils had been found in every other state along this former coast.
"Connecting the relation of these things is incredibly important for someone who studies paleontology," Becker said. "Arkansas was the last remaining piece of the shark puzzle, and we got it."
Some of the fossils they found were lying near the surface of the ground, mixed with dirt and gravel. Others took a sledgehammer to uncover.
"We pulled limestone slabs out of the river, and the bottoms of them were just covered with teeth," John Gannon, junior physics major, said.
In addition to sharks' teeth, they found mollusk fossils known as ammonites. These mollusks are known as "index fossils." Since they died out during a very narrow margin of geologic time, ammonites allow scientists to accurately determine the age of surrounding fossils.
They also found the teeth of stingrays, sawfish and enchodus, a prehistoric fish similar to a salmon with barracuda-like teeth. The site also had sedimentary structures in limestone that preserved the rippled shape of a beach.
Becker's students agreed that the hands-on experience was a valuable one.
"Being out in the field, you learn so much more about where to look for stuff than in two semesters in class," Gannon said.
"I was always interested in paleontology, but I never had the chance to do anything like this," Daniels said. "It's really been an inspiration to me. I definitely want to go on more digs."
The students also agree that traveling to a different part of the country was an interesting experience, with its local culture and catfish buffets. The time they spent traveling also brought them closer together.
"We really got to bond with the professor and other students," Catherine Jedrzejczyk, senior physics major, said.
Now, bucketfuls of gravel from the trip wait in Becker's lab to be sifted through.
Next semester, Gannon will be studying the taphonomy (the process of being buried and fossilized) involved in the site, while Daniels will work on identifying the different species of ammonites they found.
One gets the sense that Becker's students are in awe of finding something from so long ago. While on the trip, Gannon said he almost cut himself on a shark's tooth and realized, "you've got something that's 65 million years old, and it's still sharp enough to prick my finger."
"I can't wait to return to this site again," Becker said. "It holds so much promise for research and exposing students to the excitement of fossil discovery."
