SOLOMONS, Md. — Fossil discoveries along Maryland’s Calvert Cliffs reveal that ancestors of the great white shark, dating back 15 million years, consumed marine mammals like dolphins and whales despite lacking the serrated teeth of modern great whites (Carcharodon carcharias), according to a study published on June 27, 2025. The findings, led by Dr. Stephen J. Godfrey, curator of paleontology at the Calvert Marine Museum, challenge previous assumptions about the diet of the Miocene Epoch shark Carcharodon hastalis.
Modern great white sharks use boldly serrated, triangular teeth to slice energy-rich marine mammals, such as seals and dolphins, into bite-sized pieces. In contrast, Carcharodon hastalis, an ancestor from 15 million years ago, had comparably sized but unserrated teeth. Scientists long assumed this species primarily ate smaller prey, like fish, due to the lack of serrations. However, two fossilized vertebrae—one from a small dolphin and another likely from a small baleen whale—found along the fossil-rich Calvert Cliffs, contain embedded, unserrated teeth from Carcharodon hastalis. These fossils confirm that the sharks fed on marine mammals before serrated teeth evolved.
The discoveries suggest that feeding on large prey with unserrated teeth may have driven the evolution of serrated cutting edges in later species. An intermediate species, Carcharodon hubbelli, now extinct, developed lightly serrated teeth, bridging the gap to the modern great white’s steak-knife-like dentition. The study, published in Acta Palaeontologica Polonica, involved researchers from St. Mary’s College of Maryland, Johns Hopkins University Materials Science and Engineering, and syGlass, which used virtual reality to visualize a 3D scan of one embedded tooth.
One fossilized vertebra was CT-scanned at Johns Hopkins University, revealing the precise positioning of the shark tooth within the bone. The 3D visualization, processed using syGlass’s virtual reality engine, provided detailed insights into the predation event. These analyses confirmed the teeth’s pointed crowns penetrated the vertebrae, indicating active predation or scavenging by Carcharodon hastalis on marine mammals.
The Calvert Cliffs, a renowned fossil site along Maryland’s Chesapeake Bay, have yielded numerous Miocene Epoch specimens, offering a window into marine life 15 million years ago. The cliffs’ sedimentary layers preserve bones, teeth, and other remains, making them a critical resource for paleontological research. The newly discovered vertebrae add to this legacy, reshaping understanding of shark evolution and diet.
Dr. Godfrey’s team noted that the unserrated teeth of Carcharodon hastalis were still capable of inflicting significant damage, as evidenced by the embedded fossils. The dolphin and whale vertebrae, likely from juvenile or small species, suggest the sharks targeted prey similar to modern great whites but relied on different biting mechanics. The absence of serrations may have required more forceful bites or repeated attacks to process prey, potentially spurring evolutionary adaptations for efficiency.
The study highlights the interdisciplinary approach to paleontology, combining traditional fossil analysis with advanced imaging technologies. The CT scan and 3D visualization provided non-destructive methods to examine the fossils, preserving them for future research. Collaboration across institutions, including academic and technological partners, enabled a comprehensive analysis of the specimens.
These findings underscore the evolutionary pressures that shaped modern great whites. The transition from unserrated to serrated teeth likely improved feeding efficiency, allowing sharks to exploit energy-rich marine mammals more effectively. This adaptation may have contributed to the success of the great white lineage, which remains a dominant ocean predator today.
The Calvert Marine Museum, a hub for studying Chesapeake Bay fossils, continues to support research into the region’s prehistoric marine life. The cliffs, stretching along Calvert County’s shoreline, attract scientists and fossil hunters, with discoveries like these vertebrae enhancing global knowledge of shark evolution. The study’s publication marks a significant contribution to paleontology, revealing how dietary habits influenced one of the ocean’s most iconic predators.