An international team of paleontologists has discovered the oldest predatory shark known to science, belonging to the modern lamniformes lineage – the group to which today's great white sharks belong. This monster roamed off the northern coast of Australia about 115 million years ago – long before whales, megalodons and most other marine giants appeared. The work was published in the journal Communications Biology (ComBio). We are talking about a representative of the cardiabiontid family – ancient giant predatory sharks, previously known mainly thanks to finds dating back to no more than 100 million years old. New data pushes the appearance of these marine super-predators back 15 million years. The fossil was found on the coast near the city of Darwin – in an area that during the Cretaceous period was the floor of the ancient ocean connecting Gondwana and Laurasia. The area is already known for its finds of plesiosaurs and ichthyosaurs, but the new vertebrae reveal the existence of an even more impressive predator. In total, the researchers studied five vertebrae, each about 12 centimeters in diameter. They were discovered in the late 1980s and 1990s, but for a long time there remained no detailed analysis in museum collections. It is the re-examination of these patterns that enables us to reconsider their meaning. According to scientists' calculations, the shark's body length can reach 8 meters. By comparison, modern great white sharks rarely exceed 6 meters. In this case, we are talking about an ancestor that lived in an era when lamniform species were just beginning to evolve. The skeleton of a shark consists of cartilage, which is extremely poorly preserved in fossil form. Therefore, most of the findings are represented by the teeth that sharks lose throughout their lives. However, it is the vertebrae that help estimate body size more reliably. The team used data from modern ichthyology, computed tomography, mathematical modeling and comparisons with living sharks. This allowed us to reconstruct the possible appearance of the ancient predator, which according to scientists, looked almost like a “modern giant shark”. One of the important findings of the study is that the “shark” body shape has been extremely successful from an evolutionary perspective. By the mid-Cretaceous period, lamniforms had reached the top of the food chain – and since then, their basic structural scheme has remained largely unchanged. Scientists think similar giants may have existed in other parts of the ancient ocean, and now researchers plan to search for similar finds around the world.
