Allometry predicts trabecular bone structural properties in the carnivoran jaw joint

Area of Science:

• Paleontology
• Biomechanics
• Evolutionary Biology

Background:

• Cranial morphology in carnivorans is influenced by feeding and non-feeding factors.
• The temporomandibular joint (TMJ) is crucial for feeding and experiences mechanical stress, making it a potential indicator of feeding ecology.

Purpose of the Study:

• To investigate the relationship between TMJ trabecular bone structure, morphology, mechanics, and feeding ecology in Carnivora.
• To determine if regional skull characteristics like the TMJ are more sensitive to feeding ecology than whole-skull measures.

Main Methods:

• Constructed 3D models and 3D prints of the TMJ trabecular bone structure.
• Performed compression tests on TMJ models from 40 diverse carnivoran species.
• Measured morphological and mechanical performance attributes of the TMJ trabecular bone.

Main Results:

• Trabecular bone structure (fill volume, complexity, elastic modulus, compressive strength) showed no significant relationship with phylogeny or ecology.
• Body size was the primary influence on TMJ trabecular bone morphology and mechanics.
• Positive allometry was observed for structural complexity relative to centroid size and body mass.

Conclusions:

• Carnivoran TMJ trabecular bone structure does not appear to significantly remodel in response to different feeding tasks.
• Body size, rather than feeding ecology, is the dominant factor shaping TMJ biomechanics in carnivorans.
• The TMJ may be less sensitive to feeding ecology than previously hypothesized, contrary to expectations for regional skull characteristics.