Biomechanics of the Hadrosaurid dental battery: a functional approach using Finite Element Analysis

BECERRA, M.G.; TABORDA, JEREMIAS R. A.; SALINAS, G.C.; JUAREZ VALIERI, R.D.; FABIANELLI, M.N.; MESO, J. G.; PRIETO-MARQUEZ, A.

General Roca

Congreso; Reunión de Comunicaciones de la Asociación Paleontológica Argentina; 2023

Asociación Paleontológica Argentina

The hadrosaurid dental battery is one of the most complex adaptations to assist intraoral processing of a high-fiber herbivorous diet among amniotes. It comprises staggered and tightly-packed teeth with continuous replacement and systematic wear, resulting in an oblique coplanar facet in all teeth, which affects more than one tooth per dental family. The use of finite element analysis to address the cranial biomechanics in hadrosaurids is scarce, and none of this research separates teeth from each other and the jaw, nor described how the dental battery behaves in front of stress due to mastication. Our preliminary study aims testing how the hadrosaurid dentition responds to stress by using a 3D reconstructed dental battery, with detail on considering teeth as independent structures interacting with each other within the dental battery, and these with the jaw. To achieve this, we used a maxillary fragment of Willinakaqe salitralensis sensu Juarez-Valieri et al., MPCA-Pv SM 10, from the Allen Formation at Salitral Moreno (middle Campanian - lower Maastrichtian; Río Negro; Argentina). The specimen was 3D segmented, separating bone, teeth, and cement for performing the finite element models, additionally separating five successive dental families, tooth by tooth. To each finite element model, we applied the properties of the respective tissue (bone, teeth, cementum), performed the analysis using a random force of 100 N perpendicular to the upper jaw axis, and described the stress distribution along the dental battery, testing two scenarios: the first comprise the wear surface of the entire dental battery; the second with the wear facet of teeth belonging to a single dental family. In the two scenarios, when a vertical force is applied, tension spreads mainly within each dental family in apicobasal direction and reaches the bearing bone, with less propagation to the neighboring families, the latter involving the interdental contact of one tooth with those basally positioned teeth of the neighboring families, spreading basally. Our results contrast with others using hadrosaurids, given that these never separated bone from teeth, nor discriminated tissue types (considering all as bone), obtaining a uniform stress propagation along the jaw. Our study is the first considering how stress affects each tooth within the dental family and within the hadrosaurid dental battery, these are promising results considering that this sophisticated adaptation is one of the reasons for their increased adaptability and rapid success as an herbivorous component of different faunas worldwide near the end of the Cretaceous.