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Functional morphology of the jaw adductor muscles in the Canidae
Author(s) -
Penrose Fay,
Cox Philip,
Kemp Graham,
Jeffery Nathan
Publication year - 2020
Publication title -
the anatomical record
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.678
H-Index - 62
eISSN - 1932-8494
pISSN - 1932-8486
DOI - 10.1002/ar.24391
Subject(s) - adductor muscles , bite force quotient , masticatory force , anatomy , skull , biting , pterygoid muscles , biology , muscle architecture , mastication , mandible (arthropod mouthpart) , allometry , zygomatic arch , strain (injury) , biomechanics , orthodontics , zoology , medicine , ecology , genus , paleontology
Cranial form is closely allied to diet and feeding behavior in the Canidae, with the force and velocity of jaw‐closing depending on the bony morphology of the skull and mandible, and the mass, architecture, and siting of the jaw adductor muscles. Previously, little has been reported on the details of the form and function of canid jaw adductor muscles, with earlier studies basing functional hypotheses on data derived from dry skull specimens. Here we use empirically derived muscle data from fresh‐frozen specimens to explore the architecture of the muscles, and to inform finite element analyses models that predict bite force and strain energy in 12 species of wild canid. The inclusion of muscle architectural detail is shown to influence masticatory muscle force production capability calculations, indicating that muscles with longer fascicles were disadvantaged compared to muscles with shorter fascicles. No clear patterns of allometry were detected. Dietary groups were differentiated by temporalis fascicle angles, which, when allied with the differentiation of rostral length reported in previous studies, may further contribute to specializations of fast jaw‐closing or forceful jaw‐closing species. The most biomechanically demanding masticatory function is canine biting, and the highest strain energy values were reported in this loading condition, particularly in the zygomatic arches and caudal rostrum. Specific head shapes may be constrained by size, with scaled strain energy models predicting that some bony morphologies may only be viable in species with small body masses.