![]() After the K-Pg boundary, during the Palaeocene and part of the Eocene, the role of apex predator in oceans was still occupied by reptiles, with large marine crocodiles like the genera Thoracosaurus (Danian, Palaeocene) and Dyrosaurus (Ypresian, Eocene) (Gallagher Citation2003 Jouve et al. Mosasauroids were marine reptiles with a lacertiform appearance, and the largest species exceeded 10 m in length (Bullard and Caldwell Citation2010 Driscoll et al. Citation2014 Madzia and Cau Citation2017). Near the end of the Cretaceous period (98–65.5 Ma), Mosasauroidea (Squamata) roamed the seas together with Pliosauroidea and ruled the aquatic environments till the end of the Mesozoic (Polcyn et al. ![]() Pliosauroids included large-sized predators like Kronosaurus queenslandicus, with a total body length of 9–10.9 m and an estimated bite force of more than 27000 N (McHenry Citation2009 Foffa et al. From the late Triassic to the late Cretaceous, the role of marine apex predators was mainly played by marine reptiles such as the Pliosauroidea (Plesiosauria, Sauropterygia) (Foffa et al. During the Late Devonian, the top predator of the seas was the placoderm Dunkleosteus, an armoured, jawed fish more than 8 m long, and calculated to have had a bite force of 7495 N at the rear gnathal plates (Anderson and Westneat Citation2009 Ferrón et al. Once jaws had evolved, bite force became a defining characteristic of predators. Since the earliest predator–prey interaction, oceans have always had their sea monsters. Other macroraptorial sperm whales such as the roughly coeval Acrophyseter from Peru likely employed the same feeding technique. varolai likely fed via ‘grip-and-shear’ feeding, snapping the food items with an anterior bite and then cutting them with a powerful posterior bite. ![]() Considering the significant difference observed between the anterior and posterior bite forces, Z. varolai might have fed upon medium-sized marine vertebrates like other odontocetes. These values are similar to those estimated for other marine predators known for their powerful bite. varolai exerted an anterior bite force of more than 4000 N and a posterior bite force of more than 10000 N. ![]() To explore multiple bite scenarios, we set four different load cases on a 3D model of the cranium obtained via digital photogrammetry, considering the temporalis and masseter muscles as jaw adductors. Here, we estimate the bite force of Zygophyseter varolai, a macroraptorial physeteroid from lower upper Miocene strata of the Pietra leccese formation (Apulia, Italy) using the finite element analysis (FEA). Differing from the extant physeteroids, macroraptorial sperm whales are currently regarded as apex predators of the Miocene seas based on several morphofunctional observations. ![]()
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