Otodontiformes

Otodontiformes is an extinct order of mackerel sharks that lived from the Early Cretaceous to the Late Miocene epochs. These sharks are primarily known from their fossilized teeth, which are often large and robust. The most famous member of this group is Otodus obliquus, a species whose teeth could reach up to 10 cm (4 inches) in length. Otodontiformes are distinguished by their large, triangular teeth with smooth or weakly serrated edges and a prominent central cusp. The order is thought to have included some of the largest predatory fish that ever lived.

The exact phylogenetic placement of Otodontiformes within Chondrichthyes has been a subject of debate. Historically, they were often grouped with other large lamniform sharks. However, recent studies, particularly those analyzing tooth morphology and cladistic analyses, have suggested a potential divergence from the main lineage of Lamniformes, leading to their classification as a separate order. This classification emphasizes their unique evolutionary path and distinct anatomical features, especially in their dentition, which differs in cusp structure and serration patterns from many other mackerel sharks.

Fossil evidence for Otodontiformes is found globally, indicating a wide distribution during their existence. Their presence in marine sediments from various continents points to a significant ecological role in Mesozoic and Cenozoic oceans. The extinction of Otodontiformes is thought to have occurred by the end of the Miocene, possibly due to competition with other predatory sharks, changes in prey availability, or broader environmental shifts. Their disappearance marks the end of an era for some of the planet's apex predators.