Final Report Summary - THE CUTTING EDGE (The Cutting Edge: Insights from biomechanical tooth studies to explore the interaction of ecological diversity and evolutionary convergence.)
Teeth are an important aspect of vertebrate anatomy: they lie directly at the interface of the animal and its environment and are therefore an ideal tool to explore the biomechanics and ecology diversity of extinct organisms. Dental structures in vertebrates come in a wide range of shapes and sizes and are abundant in the fossil record. Tooth form, even in extinct animals, offers a direct link to whatever the animal is capable of feeding upon and how feeding was performed, i.e. their functional ecology. Furthermore, teeth have the potential to be a model system for comparisons of function and ecology across clades and through time as the mechanical processes involved in food mastication can be explored through the paradigm of universal physical laws and applied to any vertebrate group. The objective of this project was to quantify the biomechanical/ecological diversity of vertebrate dental structures over time and explore the role that evolutionary convergence plays in shaping the pattern of functional and ecological change. There were two main goals to this project: 1) Quantify the relationship between tooth shape, complexity, and function and then use the data from the first part 2) To quantify changes in the patterns and diversity of tooth design across taxa and through time.
The relationship between tooth morphology and function is highly complex and heavily influenced by the material properties of the food being eaten. Physical cutting experiments performed using a specially-designed guillotine testing device show that variation in tooth shape can have drastic effects on the energy required to fracture food. However, this is heavily influenced by the properties of the food, whether they are soft and deformable (meat) or stiff and more fibrous (vegetables) . Parallel work on beak shape in African seedcrackers shows that this is true of non-dental feeding structures as well. The types of food being chewed can also have a great impact on the types of stress and potential damage seen in teeth. Using finite element models (FEM) I tested the effects of different stresses on teeth created by different types of food. I isolated specific structures, such as a ring of enamel around the base of some mammal teeth called a cingulum, and found that the cingulum is particularly useful in reducing strains caused by chewing soft, tough foods such as gum or caramel . These results are of particular interest to dentists, who have long noted specific types of tooth damage (called abfraction), which occurs precisely in the region where a cingulum would be in human teeth.
In order to further explore the relationship between tooth form and food properties, I have pursued ways of integrating physical fracture experiments and FE models. Fully validated FE models based on physical experiments show that the relationship between food and tooth is an energetic one . Animals feed to gain energy; however, it takes energy to chew and break down food. My results show that certain tooth forms can reduce the energy required to break down food by reducing the amount of energy expended during chewing. This means that the food is being processed more efficiently at less cost to the animal. In order to further explore the relationship between tooth form and food properties, I have pursued ways of integrating physical fracture experiments and FE models. Fully validated FE models based on physical experiments show that the relationship between food and tooth is an energetic one3 . Animals feed to gain energy; however, it takes energy to chew and break down food. My results show that certain tooth forms can reduce the energy required to break down food by reducing the amount of energy expended during chewing. This means that the food is being processed more efficiently at less cost to the animal.
The relationship between tooth morphology and function is highly complex and heavily influenced by the material properties of the food being eaten. Physical cutting experiments performed using a specially-designed guillotine testing device show that variation in tooth shape can have drastic effects on the energy required to fracture food. However, this is heavily influenced by the properties of the food, whether they are soft and deformable (meat) or stiff and more fibrous (vegetables) . Parallel work on beak shape in African seedcrackers shows that this is true of non-dental feeding structures as well. The types of food being chewed can also have a great impact on the types of stress and potential damage seen in teeth. Using finite element models (FEM) I tested the effects of different stresses on teeth created by different types of food. I isolated specific structures, such as a ring of enamel around the base of some mammal teeth called a cingulum, and found that the cingulum is particularly useful in reducing strains caused by chewing soft, tough foods such as gum or caramel . These results are of particular interest to dentists, who have long noted specific types of tooth damage (called abfraction), which occurs precisely in the region where a cingulum would be in human teeth.
In order to further explore the relationship between tooth form and food properties, I have pursued ways of integrating physical fracture experiments and FE models. Fully validated FE models based on physical experiments show that the relationship between food and tooth is an energetic one . Animals feed to gain energy; however, it takes energy to chew and break down food. My results show that certain tooth forms can reduce the energy required to break down food by reducing the amount of energy expended during chewing. This means that the food is being processed more efficiently at less cost to the animal. In order to further explore the relationship between tooth form and food properties, I have pursued ways of integrating physical fracture experiments and FE models. Fully validated FE models based on physical experiments show that the relationship between food and tooth is an energetic one3 . Animals feed to gain energy; however, it takes energy to chew and break down food. My results show that certain tooth forms can reduce the energy required to break down food by reducing the amount of energy expended during chewing. This means that the food is being processed more efficiently at less cost to the animal.
