Ecological consequences of the evolution of key adaptations, and niche partitioning in C(3)-dominated environments

Key adaptations are evolution of new traits that lead to amplified diversification rates in an ensuing clade, possibly leading to adaptive radiations. Morphological evolution can lead to either ecological stenotopy or eurytopy, with the former manifest as decreased niche breadth, and the latter as increased breadth. This dissertation aims to address whether evolution of hypsodonty creates stenotopy or eurytopy, as well as determining if resource use is distinguishable before the C4 global carbon shift.; Analysis of the number of biogeographic provinces and localities occupied, as well as species longevity in taxa showed no significant difference between hypsodont and brachydont taxa. Further, preliminary isotopic data using the delta 13C values of late Pleistocene Florida ungulates reveal that hypsodont taxa have a wider variability in diet than do brachydont taxa, which suggested that hypsodont taxa are eurytopic, or ecologically generalized.; Results from the morphological analysis of occlusal tooth enamel revealed that enamel length was significantly correlated with tooth area and estimated body mass, but not with feeding strategy. The occlusal enamel length in ungulate teeth was constrained by the size of the tooth and ultimately was determined by the mass of the individual, not the diet, and therefore was no help in determining ungulate resource breadth.; Two separate isotopic analyses were further conducted to robustly test for resource use. First, analysis of ungulates from the modern Yellowstone National Park revealed that delta13C values from tooth enamel could identify resource use in C3-dominated communities, laying the groundwork for its application to ancient ecosystems. In the second analysis of the Miocene C3-dominated Black Hawk Ranch, California (BHR) and Love Bone Bed, Florida (LBB) communities, isotopic values revealed resource partitioning at LBB but not at BHR. More positive delta13C values are observed in taxa occupying open habitats at both the modern and ancient localities. The results highlight the ability of the isotopic techniques to discern resource use before the C4 global carbon shift.; The evolution of hypsodonty illustrates that the evolution of specialized morphologies can result in either ecological specialization or generalization, and that resource breadth is possible to determine in ancient taxa using isotopic techniques.