ABSTRACT
BACKGROUND In the last chapter, we looked at the fauna (mainly fishes) from the lacustrine deposits dating between the Paleocene and the late Eocene from a vast intermontane basin within the Rocky Mountain system. In this chapter, we look at another Rocky Mountain intermontane basin, slightly younger in age, which is famed for its abundance (>1700 described species) of fossil plants and animals, mainly insects. The fauna and flora living in the two regions at slightly different times in the Paleogene, are likely to have been rather similar (see comparison
later), but the circumstances of their preservation at the two sites are different.
