Functional Morphology of the Macropod Mandible: Correlating Medial Masseter Muscle Insertion and Size
Faculty Mentor
Judd Case
Presentation Type
Poster
Start Date
4-14-2026 2:00 PM
End Date
4-14-2026 4:00 PM
Location
PUB NCR
Primary Discipline of Presentation
Biology
Abstract
This project investigates the functional link between specialized tooth shape and chewing mechanics across the diverse family Macropodidae (kangaroos and wallabies). Macropods exhibit a wide spectrum of dietary specializations, ranging from dedicated grazers that process abrasive grasses to browsers that consume tough stems and leaves. A key morphological adaptation is the co-evolution of the bladed third premolar (p3) and the powerful medial masseter muscle (indicated by a deep mandibular fossa). While previous comparative anatomy has established a correlation between p3 size and fossa depth, these studies, relying on linear measurements, cannot quantify the internal stress and strain placed on the bone during chewing. I hypothesize that the presence of a larger, more pronounced p3 and an increased fossa is a specialized adaptation associated with the high-force shearing required for browsing, whereas the smaller p3 and shallower fossa reflects the lower shear-force mechanics of grazing. To test this functional hypothesis, I will examine skeletal material from Macropodidae museum collections. I will examine Macropodidae museum specimens to gather high-resolution anatomical data, moving beyond traditional descriptions toward a quantitative comparative analysis. By measuring the physical properties of mandibular structures, I aim to find significant correlations between bone geometry and chewing efficiency. These metrics will be used to simulate functional performance, revealing the biomechanical links between jaw muscle development and tooth morphology. Ultimately, this research clarifies the evolutionary relationship between structural design and dietary shifts in macropods.
Recommended Citation
Carr, Joseph, "Functional Morphology of the Macropod Mandible: Correlating Medial Masseter Muscle Insertion and Size" (2026). 2026 Symposium. 24.
https://dc.ewu.edu/srcw_2026/ps_2026/p3_2026/24
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International License.
Functional Morphology of the Macropod Mandible: Correlating Medial Masseter Muscle Insertion and Size
PUB NCR
This project investigates the functional link between specialized tooth shape and chewing mechanics across the diverse family Macropodidae (kangaroos and wallabies). Macropods exhibit a wide spectrum of dietary specializations, ranging from dedicated grazers that process abrasive grasses to browsers that consume tough stems and leaves. A key morphological adaptation is the co-evolution of the bladed third premolar (p3) and the powerful medial masseter muscle (indicated by a deep mandibular fossa). While previous comparative anatomy has established a correlation between p3 size and fossa depth, these studies, relying on linear measurements, cannot quantify the internal stress and strain placed on the bone during chewing. I hypothesize that the presence of a larger, more pronounced p3 and an increased fossa is a specialized adaptation associated with the high-force shearing required for browsing, whereas the smaller p3 and shallower fossa reflects the lower shear-force mechanics of grazing. To test this functional hypothesis, I will examine skeletal material from Macropodidae museum collections. I will examine Macropodidae museum specimens to gather high-resolution anatomical data, moving beyond traditional descriptions toward a quantitative comparative analysis. By measuring the physical properties of mandibular structures, I aim to find significant correlations between bone geometry and chewing efficiency. These metrics will be used to simulate functional performance, revealing the biomechanical links between jaw muscle development and tooth morphology. Ultimately, this research clarifies the evolutionary relationship between structural design and dietary shifts in macropods.
