A new paper:
The tyrannosaurids are among the most wellâstudied dinosaurs described by science, and analysis of their feeding biomechanics allows for comparison between established tyrannosaurid genera and across ontogeny. We used 3D finite element analysis (FEA) to model and quantify the mechanical properties of the mandibles (lower jaws) of three tyrannosaurine tyrannosaurids of different sizes. To increase evolutionary scope and context for 3D tyrannosaurine results, a broader sample of validated 2D mandible FEA enabled comparisons between ontogenetic stages of Tyrannosaurus rex and other large theropods. We found that mandibles of small juvenile and large subadult tyrannosaurs experienced lower stress overall because muscle forces were relatively lower, but experienced greater simulated stresses at decreasing sizes when specimen muscle force or surface area is normalized. Strain on postâdentary ligaments decreases stress and strain in the posterior region of the dentary and where teeth impacted food. Tension from the lateral insertion of the looping m. ventral pterygoid muscle increases compressive stress on the angular but may decrease anterior bending stress on the mandible. Low midâmandible bending stresses are congruent with ultraârobust teeth and high anterior bite force in adult Tyrannosaurus rex. Mandible strength increases with size through ontogeny in T. rex and phylogenetically among other tyrannosaurids, in addition to that tyrannosaurid mandibles exceed mandible strength of other theropods at equivalent ramus length. These results may indicate separate predatory strategies used by juvenile and mature tyrannosaurids; juvenile tyrannosaurids lacked the boneâcrunching bite of adult specimens and hunted smaller prey, while adult tyrannosaurids fed on larger prey.