Stephanie A. Martin, Bader H. Alhajeri, Scott J. Functional dental theory predicts that tooth shape responds evolutionarily to the mechanical properties of food. Most studies of mammalian teeth have focused on qualitative measures of dental anatomy and have not formally tested how the functional components of teeth adapt in response to diet. Here we generated a series of predictions for tooth morphology based on biomechanical models of food processing. We used murine rodents Old World rats and mice to test these predictions for the relationship between diet and morphology and to identify a suite of functional dental characteristics that best predict diets. One hundred and five dental characteristics were extracted from images of the upper and lower tooth rows and incisors for 98 species. After accounting for phylogenetic relationships, we showed that species evolving plant-dominated diets evolved deeper incisors, longer third molars, longer molar crests, blunter posteriorly angled cusps, and more expanded laterally oriented occlusal cusps than species adapting to animal-dominated diets.
All animals have teeth that are adapted to eating certain types of food. For instance, herbivores, because they are plant eaters, have strong and flat molars that are made for grinding leaves and small or non-existent canine teeth. Carnivores, the meat eaters of the animal world, have very defined canine teeth for tearing at meat, combined with a sometimes limited number of molars. Omnivores, because they eat both meat and plants, have a combination of sharp front teeth and molars for grinding. Herbivores have teeth that are highly specialized for eating plants. Because plant matter is often difficult to break down, the molars of herbivores are wider and flatter, designed to grind food, and aid in digestion. Herbivore incisors are sharp for tearing plants, but they may not be present on both the upper and lower jaw. White tail deer are a perfect example of an herbivore that has only lower incisors and a rigid upper jaw that assists in the tearing of plants.
Determining the diet of a species is complicated and time consuming. All of these surface area characteristics are related to the amount of food that can be broken down per mastication cycle; reduced surface area and volume results in less food processed but increased stresses on those foods. Ungulate cheek teeth: developmental, functional, and evolutionary interrelations. Animal-dominated diets do not require as much force for efficient food breakdown, so a longer, less robust jaw is expected, except in durophagous taxa. Here we generated a series of predictions for tooth morphology based on biomechanical models of food processing. Non-molar measurements condylobasal length, upper incisor depth and width, and jaw-lever length; Fig. American Journal of Physical Anthropology : — Several measures reflecting lateral cusp angle lower metacone, upper labial anterocone ah, and upper metacone ah angle proxies were selected by our standard DFA. Abstract Functional dental theory predicts that tooth shape responds evolutionarily to the mechanical properties of food. While exploring tooth development in murines, Kavanagh et al.
Animals with teeth like humans that use their molars for grinding and their incisors and canines for ripping or tearing are said to have heterodont dentition. Plant ChemCast. In: Gittleman JL ed. Van Valkenburgh, ,