A team of paleontologists, cave specialists and park rangers is exploring a trove of fossil treasures at Mammoth Cave National Park that has yielded one of the most diverse Mississippian shark faunas in North America.
During a news conference Wednesday at the park, fossil shark specialist John-Paul Hodnett of the Maryland-National Capital Parks and Planning Commission described the discoveries.
In total, at least 40 species of sharks and their relatives have been identified, including six new species.
Rare preservation of three-dimensional skeletal cartilage documented in Mammoth Cave allows researchers to understand the anatomy and relationships of these ancient sharks.
The discoveries in remote cave locations within the park were made during an ongoing paleontological resources inventory that began in November 2019.
The largest species found was Saivodus striatus, which was the apex predator of the different species found at Mammoth Cave. Hodnett said this shark is often found to be a bit larger than current great white sharks.
The 325 million-year-old fossil-rich limestone of the Mammoth Cave system was formed during the late Paleozoic Era during a period known to geologists as the Mississippian Period. At this time, the cave system was actually an ocean floor.
The park staff reported a few fossil shark teeth exposed in the cave walls of Ste. Genevieve Limestone in several locations.
Hodnett was recruited to help identify the shark fossils, which were primarily teeth and fin spines. Since most of the skeleton of sharks is composed of cartilage, rather than bone, the skeletons of sharks are rarely preserved as fossils.
“It’s very exciting,” Hodnett said of the discoveries. “It’s like training a brand new child for the world and letting other people see it. I am absolutely amazed at the diversity of sharks we see while exploring the passages that make up Mammoth Cave.
“What I’m hoping to get out of this project is to see what different kinds of sharks are at different layers, and how they change over time,” Hodnett continued. “We are getting new things we have never seen before in science. This is the only place we are finding sharks in this specific geological layer. It’s a weird mystery we are trying to solve.”
Most of the shark fossils have been discovered in areas inaccessible to visitors on cave tours, but park staff are preparing photographs, artists’ renditions and three-dimensional models for the visitors to view and explore in park exhibits.
In order for Hodnett and other team members to reach the fossil site, they had to crawl on their hands and knees for more than a quarter of a mile.
A new painting showing some of the Mississippian shark and invertebrate fauna from Mammoth Cave has been completed by paleoartist Julius Csotonyi and was premiered to the public Tuesday, which also happened to be National Fossil Day.
“We are very excited to find such an important set of fossils at the park,” said Rick Toomey, cave resource management specialist and research coordinator at Mammoth Cave National Park. “Although we have known that we had a few shark teeth in the limestone exposed in the cave, we never imagined that we would have the abundance and diversity of sharks that Hodnett has identified.”
In addition to this diversity of primitive sharks at Mammoth Cave, two partial cartilaginous skeletons of different species of sharks were also found.
One specimen was discovered by a caver with the Cave Research Foundation, and the other has been known by the park guides for years.
The preservation of cartilage in layers of Paleozoic rock is a very rare occurrence and moved the team to thoroughly document these specimens.
National Park Service geologist Jack Wood lugged equipment through narrow cave passages to capture images of the two rare specimens. Wood produced 3D models of the cartilaginous shark remains which are posted on the National Park Service website.
Paleontological resource inventories, similar to the one underway at Mammoth Cave National Park, have helped to document fossils in at least 277 different national parks throughout the United States.
These inventories enable scientists to establish baseline fossil data capturing the scope, significance, distribution and management issues related to park fossils. Many new and important fossil discoveries are tied to field inventories in national parks.
For the immediate future, Hodnett and other researchers are still going through the site to find any further discoveries. In fact, Hodnett said a new species was found only just a few days ago.
“I’ll be back for multiple trips just to collect more data,” Hodnett added. “We are literally just scratching the surface, and the information is pouring out. It’s going to take a while to process all the findings, but we are excited with what we are seeing right off the bat.”