Originating in British Columbia, Canada, these Middle Eocene leaf fossils exemplify some of the defining events of Paleobiology in the Tertiary (see discussion below). Four types of plant fossils are in association:

• Betula (Birch) - Family: Betulacaea
• Fagopsis (Oak) - Family: Fagacaea
• Pine needles - Order Coniferals
• Metasequoia (Dawn Redwood) - Family: Taxodiaceae (a Conifer that unlike the predominant evergreen Conifers was actually deciduous)

The perfect little oak leaf, betrayed urticoid teeth, is rare in the formation.

The Eocene was a period when flowering plants continued a massive radiation that began in the Paleocene Epoch. Plants thrived, and with that many animals, as new environmental niches were filled. The first grasses appeared with growth near the root as opposed to the tip, providing a renewable food resource and place of refuge for many animals. Small mammals radiated. Many new species of shrubs, trees and small plants appeared. A variety of trees thrived in a warm Eocene climate, including beech, elm, chestnut, magnolia, redwood, birch, and cedar, and more. The evolution of plants was providing a powerful selective pressure across the entire animal Kingdom, and many new symbiotic systems appeared.