Date of Award

4-2019

Degree Type

Thesis

Degree Name

Health Sciences (M.H.S.)

Department

Biomedical Sciences

First Advisor

Laura Stroik

Second Advisor

Melissa Tallman

Third Advisor

Amy Russell

Academic Year

2018/2019

Abstract

Mammalian dental anatomy has evolved in accordance with the physical properties of its diet, and multiple features on each tooth have specific functions related to the breakdown of food during mastication and ingestion. Tooth structure is under tight genetic control and much of the anatomical variation in dentition across species is related to adaptation to a specific dietary regime. This diet-dentition relationship can be exploited to reconstruct mammalian diets from fossil specimens through calculation of dental topographic metrics. To date, most studies of dietary reconstruction using dental topography have focused on mandibular molars; thus, this study seeks to test whether the dietary signal from maxillary molars is congruent with that of the mandibular dentition.

As a test case, an extant sample of maxillary and mandibular phyllostomid bat dentitions from Balta, Peru were collected and classified by dietary regime: frugivore, frugivore-nectarivore, insectivore-frugivore, and insectivore. The specimens were cast using epoxy material, after which second molars were excised, mounted on discs, and microCT-scanned at 13μm resolution. The resulting images were compiled to create a 3D surface model of the anatomical tooth crown, and topographic metrics were then calculated.

Paired t-tests of relief index (RFI), Dirichlet normal energy (DNE), and orientation patch count-rotated (OPCR) values of maxillary and mandibular molars within each dietary group demonstrated that there is a significant difference between maxillary and mandibular dental topographies across diets (P<0.05). Additionally, discriminant function analysis of maxillary and mandibular dental topography indicated that maxillary second molars are as effective at predicting a species’ diet as mandibular molars, and a combination of maxillary and mandibular dental topographic values predicts diet more effectively with an 65% success rate. Results from this study increase the dietary prediction accuracy for complete fossil specimens, expand paleontological dental topographic analysis to include maxillary molars, and demonstrate the potential of incorporating an occlusal approach to dental topography.

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