Accuracy of mandibular force profiles for bite force estimation and feeding behavior reconstruction in extant and extinct carnivorans

Abstract

Mandibular force profiles apply the principles of beam theory to identify mandibular biomechanical properties that reflect the bite force and feeding strategies of extant and extinct predators. While this method uses the external dimensions of the mandibular corpus to determine its biomechanical properties, more accurate results could potentially be obtained by quantifying its internal cortical bone distribution. To test this possibility, mandibular force profiles were calculated using both external mandibular dimensions ('solid mandible model') and quantification of internal bone distribution of the mandibular corpus obtained from computed tomography scans ('hollow mandible model') for five carnivorans (Canis lupus, Crocuta crocuta, Panthera leo, Neofelis nebulosa and the extinct Canis dirus).Comparison reveals that the solid model slightly overestimates mandibular biomechanical properties, but the pattern of change in biomechanical properties along the mandible remains the same. As such, feeding behavior reconstructions are consistent between the two models and are not improved by computed tomography. Bite force estimates produced by the two models are similar, except in C. crocuta, where the solid model underestimates bite force by 10-14%. This discrepancy is due to the more solid nature of the C. crocuta mandible relative to other carnivorans. Therefore, computed tomography improves bite force estimation accuracy for taxa with thicker mandibular corpora, but not significantly so otherwise. Bite force estimates derived from mandibular force profiles are far closer to empirically measured bite force than those inferred from jaw musculature dimension. Consequently, bite force estimates derived from this method can be used to calibrate finite-element analysis models.

The diet of early birds based on modern and fossil evidence and a new framework for its reconstruction

“…The bite point is typically operationalised as the rostralmost or cranialmost point of the occlusal surface (either of the rhamphotheca or apices of teeth) (Ma et al ., 2020; Navalón et al ., 2018 a ). More rarely MA will be calculated for each tooth in the row (Sakamoto, 2010; Therrien et al ., 2016; Cox, 2017). Functionally, MA is seen as the trade‐off between speed and power in skull architecture (Stayton, 2006; Dumont et al ., 2014; Corbin et al ., 2015; Adams et al ., 2019), although this trade‐off is a simplification and can be circumvented (McHenry & Summers, 2011; Corbin et al ., 2015).…”

Quantifying bite force in coexisting tayassuids and feral suids: a comparison between morphometric functional proxies andin vivomeasurements

“…Measurements of muscle scars and lever systems based on bone structures have been used as proxies to infer properties of skull-jaw mechanics and make functional comparisons among mammalian groups (Davis, 1955;Davis, 1964;Turnbull, 1970;Kiltie, 1982;Kiltie, 1985;Emerson & Radinsky, 1980;Radinsky, 1981a;Radinsky, 1981b;Radinsky, 1987;Sicuro & Oliveira, 2002;Therrien, Henderson & Ruff, 2005;Wroe, McHenry & Thomason, 2005;Hendges et al, 2019). In the last two decades, Finite Element Analysis (FEA) became a new way to assess stress resistance of osteological structures to strain forces, such as compression, shearing, and torsion (Richmond et al, 2005;Fletcher, Janis & Rayfield, 2010;Tseng & Binder, 2010;Tseng et al, 2011;Cox, Rinderknecht & Blanco, 2015;Therrien et al, 2016;Lautenschlager et al, 2017;Morales-García et al, 2019). Some of these methods are quite complex and Cardini (2020) criticizes what he considers an excessive focus on complex mathematical models to describe the form and function of structures rather than their real ecomorphological meaning.…”

Evolutionary allometry and ecological correlates of fang length evolution in vipers

“…As ratios are problematic forms of control in regression models [24], regression models described below use raw fang length as the independent variable, while including head length as a covariate. We also report relative fang length as fang length divided by head length, as this proportion is an independent complex trait of each species [25], preserves the allometric component of fang length and is both functionally relevant [26] and intuitive (e.g. fang length can be discussed as a percentage of head length).…”