The Evolution of Camelids in the Pacific Northwest in Response to the Grassland Expansion
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Date
2020
Authors
Froehlich, Eleanor
Journal Title
Journal ISSN
Volume Title
Publisher
University of Oregon
Abstract
Camelids, the artiodactyl group including camels, llamas, and alpacas, evolved in North America during the Eocene. The first camelids were smaller than a goat; however, some extinct genera were giraffe sized. Most studies of North American camelids focus on fossils found in the Great Plains and as a result little is known about how camelid diversity responded to climate and vegetation changes in the Pacific Northwest. Horses are a well-studied example of ungulate responses to climactic changes and grassland expansion. They show a general increase in body size that is concurrent with their switch from browsing to mixed feeding and eventually to the grazing we see in modern examples. I suspect that as the environment in the Pacific Northwest dried out, camelids also increased in size due to the grassland expansion. I also believe that camelids incorporated more grasses into their diet. I tested this by documenting camelid diversity in the Pacific Northwest, specifically the states of Idaho, Oregon, and Washington, using the published fossil occurrences on the Paleobiology Database. Body size data was estimated using tooth measurements collected on the Fossilworks database. Camelid species were categorized according to two ecological parameters, body size and diet. I used these to track camelid evolution through time. I found that although body mass does increase there were still small browsing lineages late into the Miocene. This study provides a broader biogeographical picture of how grassland expansion influenced camelid evolution and ecology.
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Keywords
paleontology, paleoecology, evolution, camelids