Scaling and Accommodation of Jaw Adductor Muscles in Canidae

Penrose, Fay; Kemp, Graham J.; Jeffery, Nathan

doi:10.1002/ar.23355

Cited by 20 publications

(31 citation statements)

References 57 publications

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“…Jaw adductor MM scaled isometrically against BM and with slight positive allometry against GM. These results mirror trends seen in the jaw adductors of Felids (Hartstone-Rose et al, 2012) and within Canids (Penrose et al, 2016). Weighted FLs scaled with negative allometry against both size variables, which is also consistent with the results of felid jaw adductor FL.…”

Section: Scaling Of Architectural Properties Within the Musteloideasupporting

confidence: 84%

Bite Force and Masticatory Muscle Architecture Adaptations in the Dietarily Diverse Musteloidea (Carnivora)

Hartstone‐Rose

Hertzig

Dickinson

2019

The Anatomical Record

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Dietary ecology and its relationship with both muscle architecture and bite force potential has been studied in many mammalian (and non‐mammalian) taxa. However, despite the diversity of dietary niches that characterizes the superfamily Musteloidea, the masticatory muscle fiber architecture of its members has yet to be investigated anatomically. In this study, we present myological data from the jaw adductors in combination with biomechanical data derived from craniomandibular measurements for 17 species representing all four families (Ailuridae, Mephitidae, Mustelidae, and Procyonidae) of Musteloid. These data are combined to calculate bite force potential at each of three bite points along the dental row. Across our sample as a whole, masticatory muscle mass scaled with isometry or slight positive allometry against both body mass and skull size (measured via a cranial geometric mean). Total jaw adductor physiological cross‐sectional area scaled with positive allometry against both body mass and skull size, while weighted fiber length scaled with negative allometry. From a dietary perspective, fiber length is strongly correlated with dietary size such that taxa that exploit larger foods demonstrated myological adaptations toward gape maximization. However, no consistent relationship between bite force potential and dietary mechanical resistance was observed. These trends confirm previous findings observed within the carnivoran family Felidae (as well as within primates), suggesting that the mechanisms by which masticatory anatomy adapts to dietary ecology may be more universally consistent than previously recognized. Anat Rec, 302:2287–2299, 2019. © 2019 American Association for Anatomy

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Section: Scaling Of Architectural Properties Within the Musteloideasupporting

confidence: 84%

Bite Force and Masticatory Muscle Architecture Adaptations in the Dietarily Diverse Musteloidea (Carnivora)

Hartstone‐Rose

Hertzig

Dickinson

2019

The Anatomical Record

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“…Details of the muscle dissections can be found in Penrose et al (). In a fox head dissection ( Vulpes vulpes 7), we found that the lateral pterygoid contributed approximately 3% to the overall pterygoid mass (medial pterygoids 8.71 g, lateral pterygoids 0.28 g), and 0.27% to the total jaw adductor muscle mass.…”

Section: Resultsmentioning

confidence: 99%

“…All concur that its role is likely to be insignificant due to its small size and the bony constraints of the TMJ (Hartstone‐Rose, Perry, & Morrow, ; Herring, ; Ström, Holm, Clemensson, Haraldson, & Carlsson, ; Turnbull, ). Further details of the dissection protocol can be found in Penrose et al (Penrose et al, ). The specimen that had undergone MR scanning at both occlusion and wide gape, Vulpes vulpes 6, was also subsequently dissected and photographed at occlusion and wide gape, to confirm the limit of gape ( Vulpes vulpes 6 dissected at wide gape is shown in Figure b).…”

Section: Methodsmentioning

confidence: 99%

“…Previous analyses indicated that the differences in form of the cranial part of the skull are associated with changes in body mass and, specifically, that shape change is related to housing the jaw adductor muscles on the cranium (Penrose, Kemp, & Jeffery, ). Body mass related shape change is associated with the disparity in scaling between the jaw adductor muscles, which scale isometrically, and brain volume, which scales with negative allometry (Penrose et al, ; Radinsky, ). This does not, however, preclude the possibility that there may be further functionality of cranial shape differences in addition to increasing surface area.…”

Section: Introductionmentioning

confidence: 99%

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Functional morphology of the jaw adductor muscles in the Canidae

Penrose

Cox

Kemp

et al. 2020

The Anatomical Record

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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.

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“…Furthermore, musteloid estimated bite force scales with positive allometry relative to cranial size, a pattern that is consistent with estimated bite force scaling relative to body mass across all of Carnivora (Christiansen & Wroe, ). Because larger carnivorans exhibit larger jaw adductor muscles that can generate larger bite forces (Hartstone‐Rose et al ., ; Penrose et al ., ), our results suggest that musteloids evolved larger bite forces simply through evolutionary shifts towards larger head and body and head sizes.…”

Section: Discussionmentioning

confidence: 99%

Effects of diet on cranial morphology and biting ability in musteloid mammals

Law

Duran

Hung

et al. 2018

J of Evolutionary Biology

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Size and shape are often considered important variables that lead to variation in performance. In studies of feeding, size‐corrected metrics of the skull are often used as proxies of biting performance; however, few studies have examined the relationship between cranial shape in its entirety and estimated bite force across species and how dietary ecologies may affect these variables differently. Here, we used geometric morphometric and phylogenetic comparative approaches to examine relationships between cranial morphology and estimated bite force in the carnivoran clade Musteloidea. We found a strong relationship between cranial size and estimated bite force but did not find a significant relationship between cranial shape and size‐corrected estimated bite force. Many‐to‐one mapping of form to function may explain this pattern because a variety of evolutionary shape changes rather than a single shape change may have contributed to an increase in relative biting ability. We also found that dietary ecologies influenced cranial shape evolution but did not influence cranial size nor size‐corrected bite force evolution. Although musteloids with different diets exhibit variation in cranial shapes, they have similar estimated bite forces suggesting that other feeding performance metrics and potentially nonfeeding traits are also important contributors to cranial evolution. We postulate that axial and appendicular adaptations and the interesting feeding behaviours reported for species within this group also facilitate different dietary ecologies between species. Future work integrating cranial, axial and appendicular form and function with behavioural observations will reveal further insights into the evolution of dietary ecologies and other ecological variables.

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Scaling and Accommodation of Jaw Adductor Muscles in Canidae

Cited by 20 publications

References 57 publications

Bite Force and Masticatory Muscle Architecture Adaptations in the Dietarily Diverse Musteloidea (Carnivora)

Bite Force and Masticatory Muscle Architecture Adaptations in the Dietarily Diverse Musteloidea (Carnivora)

Functional morphology of the jaw adductor muscles in the Canidae

Effects of diet on cranial morphology and biting ability in musteloid mammals

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