Italiano: Jaw muscles of Basilosaurus isis and constraints for FEA. A. Jaw muscles of B. isis and muscle vector and moment arms for leverage-based force calculation. B. Adductors (red arrows) mapped onto a CTbased finite element model of the cranium of Basilosaurus isis WH-74, including the dentaries. C. Constraints for finite element analyses. In the all-muscles active analysis, the cranium was fully constrained at the left and right temporomandibular joints (TMJ), and tooth constraints were applied in respective bite analyses. In the posterior shear analysis, the only active muscles are the posterior temporalis, and only P3 is constrained.