Patterns in the Evolution of Herbivory in Large Terrestrial Mammals: The Paleogene of North America

By: Christine M. Janis

In this paper I examine the generic richness through Paleogene time of ungulates and ungulate-like mammals distinguished both by dental morphology (=dietary type) and body size. Many of these general dietary trends have been discussed by other workers (e.g., Wing and Tiffney 1987, Collinson and Hooker 1991, Maas and Krause 1994, Gunnell et al. 1995). However, this paper represents a new approach by attempting to quantify patterns of change in dental morphologies and also examining patterns in the evolution of body size, specifically fucusing on ungulates and ungulate-like mammals. Hernvall, Hunter and Fortelius (1996, in press), convergently with the inception of this work, adopted a somewhat similar approach to the quantification of dental morphologies, but their work has broader range (including all of the Northern Hemisphere) and uses faunal data that are of coarser resolution. This paper not only provides a quantification of some generally known trends but arrives at some novel conclusions, such as the speculation (based on the dietary habits of the ungulates) that the initial climatic event in the middle Eocene of the continental interior of the US was drying rather than cooling.

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