Scientists have discovered fossils of a basking shark belonging to the order Lamniformes in northern Australia that is about 115 million years old. This discovery shows that these large ocean sharks reached their enormous size much earlier than previously thought. The work has been published in the journal Communications Biology (ComBio:).
Lamniformes is an order of sharks commonly known as herring sharks. It includes some of the most famous sharks, such as the great white and mako sharks, as well as lesser-known species, such as the goblin shark and megamouth shark.
The vertebrae were found on the coast near Darwin, part of the Tethys Ocean during the Cretaceous period. Normally, sharks only retain their teeth because their skeleton is cartilaginous, so large vertebrae are rare. The five parts found were very similar to the vertebrae of a modern great white shark. But if in adult white sharks they reach a diameter of about 8 cm, then in Darwin's fossil predator the width exceeds 12 cm.
The morphology of their vertebrae allows them to be classified as cardabiodontids – giant predatory sharks that inhabited the world's oceans about 100 million years ago. However, new data suggest that Darwin's lamniformes were around 15 million years old and even then had reached sizes typical of cardabiodontids.
The authors estimate that these sharks grew to six to eight meters long and weighed more than three tons, occupying niches as apex predators in the group's evolution. They live in shallow coastal waters and are able to compete with large marine reptiles.
Researchers say the discovery rewrites the evolutionary chronology of sharks and highlights the importance of Australian fossils in understanding ancient ecosystems. Each new fragment helps restore a picture of the oceans, where giant predators ruled millions of years ago.
