Blaire Van Valkenburgh
GE CLST 70A - Evolution of Cosmos and Life
GE CLST 70B - Evolution of Cosmos and Life
GE CLST 70CW - Evolution of the Cosmos and Life: Special Topics in Life Sciences
The questions which interest me are both ecological and evolutionary, and I approach them from the perspective of a paleobiologist and functional morphologist. My organisms of choice are vertebrates, particularly mammals. In several studies, I explored the effects of competition, prey diversity and environment on predator morphologies within past and present communities. In this work, I used the tools of biomechanics to infer critical aspects of carnivore feeding and locomotor behavior from skeletal and dental morphology. For example, quantitative indices of claw shape, limb proportions, joint mechanics and body size were used to determine locomotor behavior. Similar indices describing relative tooth size and shape indicated dietary content among living and extinct predators. Based on these morphologic indices of behavior, I was able to compare the pattern of ecological separation among coexisting carnivores in several ancient and modern communities, all of which differed in prey diversity and/or vegetation structure. Future work will expand the array of time periods sampled and attempt to follow the course of morphological divergence within a single community over several million years. Most recently, I completed an analysis of tooth fracture frequencies in the large carnivores of the Pleistocene Rancho La Brea tarpits. Comparisons with a sample of modern carnivores, such as hyenas and wolves, revealed that the big meat-eaters of the tar pits suffered up to five times more tooth breakage. Apparently, the now extinct dire wolves, American lions, and sabertooth cats, were forced to consume their kills more fully, chewing the bones, and thereby injuring their teeth. Carnivores eat more bone when prey are difficult to acquire and thus the high tooth fracture frequencies suggest competition for food was more intense ten to thirty thousand years ago. Studies underway include an exploration of the growth and development of bite strength in members of a captive population of spotted hyenas, analysis of feeding behavior in large African carnivores, and further studies of tooth fracture frequencies in additional mammalian species.
Koepfli, K-P., Jenks, S.M., Eizirik, E., Zahirpour, Van Valkenburgh, B., and Wayne, R.K.. 2006. Molecular systematics of the Hyaenidae: relationships of a relictual lineage resolved by molecular supermatrix Molecular Phylogenetics and Evolution 38: 603-620.
Munoz-Duran, J. and Van Valkenburgh. B.. 2006. The Rancholabrean record of Carnivora: taphonomic effect of body size, habitat breadth, and the preservation potential of caves Palaios 21: 424-430.
Van Valkenburgh, B., Wang, X., and Damuth, J.. 2004. Copeâ€™s rule, hypercarnivory, and extinction in North American canids Science 306: 101-103.
Van Valkenburgh, B.. 2004. How to build a dog. Part 1: A bonanza of senses The Bark 27: 32-35.
Van Valkenburgh, B.. 2004. How to build a dog. Part 2: Form follows function The Bark 28: 40-44.
Van Valkenburgh, B. and Molnar, R.E.. 2003. Dinosaurian and mammalian predators compared Paleobiology 28: 527-543.
Spencer, L. , B. Van Valkenburgh, and J. M. Harris.. 2003. Taphonomic analysis of large mammals recovered from the Pleistocene Rancho La Brea tar seeps Paleobiology 29: 561-575.
Binder, W., Thompson, E.N. and Van Valkenburgh, B.. 2002. Temporal variation in tooth fracture among Rancho La Brea dire wolves Journal of Vertebrate Paleontology 22: 423-428.
Van Valkenburgh, B., and Sacco, T.. 2002. Sexual dimorphism and intra-sexual competition in large Pleistocene carnivores Journal of Vertebrate Paleontology 22: 164-169.
Van Valkenburgh, B and Jenkins, I.. 2002. Evolutionary patterns in the history of Permo-Triassic and Cenozoic synapsid predators
The Fossil Record of Predation. M. Kowalewski, P.H. Kelley (eds). Paleontological Society Special Publications Vol. 8 267-289.