Qualitative approaches reveal parallelism of mandibular function in therian carnivores
Data files
Oct 06, 2025 version files 102.60 KB
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README.md
3 KB
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Supplementary_Table_1(1).csv
22.12 KB
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Supplementary_Table_2.csv
7.62 KB
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Theria_LM_tps_format.txt
24.46 KB
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Therian_mandible_manuscript_code.R
45.39 KB
Abstract
The evolution of the mandible in mammalian carnivores is influenced by ecological demands that have changed over their phylogenetic history. We combined geometric morphometrics and biomechanical analysis (including beam analysis and finite element analysis or FEA) to assess the interaction between form and function as the mandible has adapted independently to carnivorous diets in therian clades, including Metatheria, Mesonychia, “Creodonta,” and Carnivoramorpha. Our goal was to determine the relative contributions of mechanical advantage, mandibular force or resistance to bending and torsion, to the evolution of mandibular shape in these groups, and to determine whether they produce differential rates of shape evolution in the horizontal and ascending rami, which respectively are the tooth-bearing and muscle-loading parts of the structure.
We found that the ascending ramus has higher rates of evolution than the horizontal ramus, making it the more rapidly evolving portion of the mandible. Statistical evaluation supports this interpretation as mechanical advantage and resistance to force explain more of the variance in shape than do the beam mechanics estimates that are heavily influenced by the mandibular body. Regression analysis shows that the evolution of specialized carnivory was associated with stronger mandibles in which mandibular shape changed by shortening and thickening of the mandible, increasing the areas of muscle attachment, and increasing the carnassial blade length. Principal component analysis of mandible shape shows that different clades in Theria have been able to fill out similar specialized carnivorous niches with similar functional metrics despite having different mandibular morphologies.
Dataset DOI: 10.5061/dryad.d7wm37qd7
Description of the data and file structure
- Supplementary_Table_1(1).csv contains all the specimens used in this study, their categorical information (i.e., taxonomic group and dietary ecology), and functional morphological/biomechanical measurements that were used in data analyses. Measurements include mandible length (measured in centimeters), surface area (measured in cm2), volume (measured in cm3), dorosventral bending force (DBF) which is a ratio, labiolingual bending force (LBF) which is a ratio, relative mandibular force (RMF) which is a ratio, mechanical advantage (MA) which is ratio between lever arms between either the masseter or temporalis muscle in-levers and either the canine or carnassial out-levers, stress (measured in pascals) for loads of scaled 100 N (newtons) on the canine or the canrassial, and the strain (a dimensionless unit) for a load of scaled 100 N on the canine.
- Supplementary_Table_2.csv is the result of the convergence testing of volumetric average stress data of derived dietary ecologies with raw Ct1, Ct2, Ct3, and Ct4 values for the overall groups and taxonomic pairs.
- Theria_LM_tps_format.txt is the landmark coordinates for all specimens used for geometric morphometric analyses in TPS format. This can be loaded in geometric morphometric analysis software/code packages such as geomorph in R using the function readland.tps.
- Therian_mandible_manuscript_code.R is the R code script used to run the analyses, including geometric morphometrics (including Procrustes alignment, multivariate regression, ANOVA, determining mean shapes, and comparing rates of shape evolution), phylogenetic analysis, and convergent analysis. Code compatible with R Studio to read and work with.
Access information
Other publicly accessible locations of the data:
- Zenodo
Data was derived from the following sources:
- Museums: the American Museum of Natural History; USA (AMNH), Natural History Museum, London (formerly the British Museum of Natural History); UK (BMNH), the Egyptian Geological Museum; Egypt (CGM), Museo de Paleontologia, Facultad de Ciencias Exactas, Fisicas y Naturales de la Universidad Nacional deo Cordoba; Argentina (CORD-PZ), Indiana University Paleontology Collections; USA (IUPC), Museo de Historia Natural “Alcide d’Orbigny;” Bolivia (MHNC), Muséum d’Histoire Naturelle de Toulouse; France (MHNT.PAL), Museum National d’Historie Naturelle; France (MNHN), Museo Regional Provincial “Padre M. J. Molina;” Argemtoma (MPM-PV), University of Michigan Museum of Zoology; USA (UMMZ), University of Florida; USA (UF), Smithsonian Institution National Museum of Natural History; USA (USNM), Yale Peabody Museum; USA (YPM)
- Data acquisition was either taken in person, from photographs posted on museum databases, or from published research papers.