By combining muscle architectural data with biomechanical variables relating to the jaw, we produce anatomically derived maximum bite force estimations for 23 species of catarrhine and platyrrhine primates. We investigate how bite force scales across the sample as a whole (and within each parvorder) relative to two size proxies, body mass and cranial geometric mean, and the effect of diet upon bite force. Bite force is estimated at three representative bite points along the dental row: the first maxillary incisor, canine, and third‐most mesial paracone. We modeled bite force by combining calculated physiological cross‐sectional area of the jaw adductors from Hartstone‐Rose et al. [Anat Rec 301 (2018) 311–324] with osteological measurements of lever‐ and load‐arm lengths from the same specimens [Hartstone‐Rose et al., Anat Rec 295 (2012) 1336–1351]. Bite force scales with positive allometry relative to cranial geometric mean across our entire sample and tends toward positive allometry relative to body mass. Bite force tends toward positive allometry within platyrrhines but scales isometrically within catarrhines. There was no statistically significant scaling difference with diet. Our findings imply an absence of a dietary signal in the scaling of bite force, a result that differs from the scaling of physiological cross‐sectional area alone. That is, although previous studies have found a dietary signal in the muscle fiber architecture in these species, when these are combined with their leverages, that signal is undetectable. On the parvorder level, our data also demonstrate that the platyrrhine masticatory system appears more mechanically advantageous than that of catarrhines. Anat Rec, 2019. © 2019 American Association for Anatomy Anat Rec, 303:2026–2035, 2020. © 2019 American Association for Anatomy
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
more » « less- PAR ID:
- 10456291
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- The Anatomical Record
- Volume:
- 302
- Issue:
- 12
- ISSN:
- 1932-8486
- Page Range / eLocation ID:
- p. 2287-2299
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Carnivorans represent extreme ecomorphological diversity, encompassing remarkable variation in form, habitat, and diet. The relationship between the masticatory musculature and dietary ecology has been explored in a number of carnivoran lineages, including felids and the superfamily Musteloidea. In this study, we present novel architectural data on two additional carnivoran families—Ursidae and Canidae—and supplement these previous studies with additional felid, musteloid, herpestid, hyaenid, and viverrid taxa (a total of 53 species across 10 families). Gross dissection data were collected following a standardized protocol—sharp dissection followed by chemical digestion. Summed jaw adductor forces were also transformed into bite force estimates (BF) using osteologically calculated leverages. All data were linearized, log‐transformed, and size‐adjusted using two proxies for each taxon—body mass (BM) and cranial geometric mean—to assess relative scaling trends. These architectural data were then analyzed in the context of dietary ecology to examine the impact of dietary size (DS) and dietary mechanical properties (DMP). Muscle mass, physiological cross‐sectional area, and BF scaled with isometry or positive allometry in all cases, whereas fascicle lengths (FLs) scaled with isometry or negative allometry. With respect to diet, BM‐adjusted FLs were strongly correlated with DS in musteloids, but not in any other lineage. The relationship between size‐adjusted BF and DMP was also significant within musteloids, and across the sample as a whole, but not within other individual lineages. This interfamilial trend may reflect the increased morphological and dietary diversity of musteloids relative to other carnivoran groups.
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ABSTRACT The masticatory apparatus has been the focus of many studies in comparative anatomy—especially analyses of skulls and teeth, but also of the mandibular adductor muscles which are responsible for the production of bite force and the movements of the mandible during food processing and transport. The fiber architecture of these muscles has been correlated to specific diets (e.g., prey size in felids) and modes of foraging (e.g., tree gouging in marmosets). Despite the well‐elucidated functional implications of this architecture, little is known about its ontogeny. To characterize age‐related myological changes, we studied the masticatory muscles in a large (
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Abstract Jaw muscles are key features of the vertebrate feeding apparatus. The jaw musculature is housed in the skull whose morphology reflects a compromise between multiple functions, including feeding, housing sensory structures, and defense, and the skull constrains jaw muscle geometry. Thus, jaw muscle anatomy may be suboptimally oriented for the production of bite force. Crocodylians are a group of vertebrates that generate the highest bite forces ever measured with a flat skull suited to their aquatic ambush predatory style. However, basal members of the crocodylian line (e.g.,
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