Researchers Uncover Remains of Prehistoric Shark Species Even Older Than Dinosaurs in a Cave in America

The legacy of "sea dogs" has welcomed two more chapters. Two new species of prehistoric sharks have been discovered by experts in the deep geological layers of the USA, according to Daily Galaxy. They did the findings as part of the Paleontological Resource Inventory, a program facilitated by the National Park Service (NPS). Findings regarding these species have been detailed in the Journal of Vertebrate Paleontology. The two previously unknown prehistoric shark species uncovered by experts are "Troglocladodus trimblei" and "Glikmanius careforum."

NPS claimed that the former was named after the park superintendent who found the first specimen, and the latter in honor of the Cave Research Foundation (CRF). Remains of the species were spotted in Mammoth Cave National Park in Kentucky, as well as a northern Alabama site. Examinations revealed that both species date back to somewhere around 325 million years and belong to an ancient family called ctenacanths. It makes them even older than dinosaurs. These species were deemed distant relatives of modern sharks. 

Also, NPS released a reconstruction of these prehistoric shark species. The digital image showcases two T. trimblei floating above with G. careforum in the foreground. Experts believe these creatures were more suited for coastal conditions and exhibited behavior similar to grey sharks. Findings like these aid the organization as well as experts to better their analysis of marine biodiversity on Earth and how sharks evolved through it. In 2019, Park Superintendent Barclay Trimble of Mammoth Cave National Park discovered the first specimen of prehistoric shark fossils in a single ancient tooth belonging to T. trimblei, according to Earth.

This was followed by several similar discoveries. Researchers believe that these fossils were preserved in an exceptional state in the cave because of the area's stable temperature. Further analysis of these prehistoric shark fossils showcased that both species were around 10–12 feet (3–3.6 meters) in length. The size is similar to that exhibited by the modern oceanic whitetip shark. The fossils of prehistoric sharks were compared with specimens from the same period detected in other parts of the world. The comparison helped experts understand how sharks evolved in terms of skeletal features, tooth arrangement, and body size. Such a database could help experts understand how fish diversity has changed due to the transformation in oceans and the merging of landmasses.

One of the most noteworthy specimens in the cave turned out to be a set of jaws from a young G. careforum for experts. This sample was valuable for researchers due to its exceptional preservation, which typically did not happen in shark fossils containing cartilage. It allowed experts to understand how cartilage evolved in prehistoric sharks and provided them with more insights about the beast. The cartilage's examination showcased that G. careforum possibly sported a short head with exceptional bite ability. Experts believe that this ability allowed the creatures to prey on beings like orthocones and smaller fish. 

Moreover, fossils of T. trimblei indicated a unique tooth pattern in these creatures. These prehistoric beings displayed a branching design, which seemed to help them hunt within the Mississippian seas. Researchers believe that both T. trimblei and G. careforum shared the same habitat, which stretched across waters in modern-day Kentucky and Alabama. Other creatures in this habitat possibly included shelled organisms, bony fish, and other marine beings. They collected the remains of these prehistoric sharks in limestone formations deposited sometime between the Middle to Late Mississippian Period.

To date, 70 ancient fish species have been detected in this cave system. The previous findings were not surprising to experts. The researchers already knew that the region was once submerged under shallow seas, and therefore, the remains of ancient marine species did not raise any eyebrows. The prehistoric shark fossil discoveries in Mammoth Cave National Park, though, have attracted the attention of experts worldwide. It is essential because the remains can add to the ongoing pursuit of understanding how shark groups diversified when the supercontinent Pangea was being built.

Many scientists believe these fossils could provide them with a glimpse of the marine environment that thrived when present-day eastern North America was enveloped by a warm sea. These prehistoric fossils were spread across multiple rock layers. Tracing these fossils allowed experts to understand how the environment changed across thousands of years in the region. The insights revealed that the levels of coastal waters fluctuated as landmasses came close to each other, eventually merging into one continent. Researchers think such movements impacted the evolution and composition of ancient sharks like T. trimblei and G. careforum.