The evolution of Carnivoramorpha: Phylogenetic and morphological diversification

In this dissertation, I investigate the phylogenetic, taxonomic and morphological radiation and diversification of carnivoramorphans (stem-group “Miacoidea” and crown-clade Carnivora) and other mammalian meat-eaters (eg. Creodonta). The phylogenetic portion of this thesis focuses on the relationships and diversification of most basal members of the Carnivoramorpha. Four new specimens of basal carnivoramorphans (representing two genera and one new species) are described. The specimens include the first cranial material known for these two genera and significantly increase our knowledge of these taxa and of the earliest members of Carnivoramorpha, which historically have been grouped in the non-monophyletic carnivoramorphan stem-group “Miacoidea”. Using these new specimens, I provide the first phylogenetic analysis incorporating a broad taxonomic sample of the “Miacoidea”, and representatives of extant carnivorans, using numerous characters from the dentition and cranium. The monophyly of Viverravidae is strongly supported, and is sister-group to the remaining Carnivoramorpha. “Miacidae” is not monophyletic and appears to be a paraphyletic stem-group. The most significant result is the strong support for the exclusion of both “Miacidae” and Viverravidae from Carnivora (as phylogenetically defined).; The evolutionary history of a clade has traditionally been studied through phylogenetics, and taxonomic diversity has been used as a crude proxy for morphological diversity. However, morphological diversification can provide a very different view of a clade's evolutionary history and allows the investigation of patterns and timing of morphological evolution.; I present a new method that describes the dentition of Carnivoramorpha and other mammalian meat-eaters (Creodonta), and tested its ability to accurately discriminate diet in living taxa. Using this method, I document the pattern of morphological and taxonomic diversification of Carnivoramorpha and mammalian meat-eaters in North America, and test the hypotheses that (1) morphological diversification was suppressed relative to taxonomic diversification, early in the evolutionary history of Carnivoramorpha; and (2) once an efficient system for consuming meat evolved, the dental system remained relatively unchanged. The first hypothesis is rejected as taxonomic and morphological diversity increase together through the clade's early evolution. The second hypothesis is supported as the ecological group “mammalian meat-eaters” rapidly diversified morphologically, and reached its maximum disparity early in its history.