Figure 97 from: Sereno P (2012) Taxonomy, morphology, masticatory function and phylogeny of heterodontosaurid dinosaurs. ZooKeys 226: 1-225. https://doi.org/10.3897/zookeys.226.2840

Figure 97 - Jaw adductor musculature and keratin sheathing in a psittaciform bird and parrot-beaked dinosaur. Differentiation of facial components of the adductor muscle mass to increase bite force A Pionites leucogaster (white-bellied parrot) (from Sereno et al. 2010) B Psittacosaurus gobiensis with inferred jaw muscles and keratin sheathing (from Sereno et al. 2010). Abbreviations: amep adductor mandibulae externus profundus ames adductor mandibulae externus superficialis amev adductor mandibulae externus ventralis dm depressor mandibulae psm pseudomasseter pt pterygoideus ptvl pterygoideus ventralis lateralis.