Eocene Alnus Fossil Leaf from McAbee Fossil Beds

Coming from the McAbee Fossil Beds in British Columbia, Canada, this Middle Eocene plant fossil plate represents some of the defining events of Paleobiology in the Tertiary (see discussion below). The high-carbon fine preservation is owing to a fine layer of silt that accumulated over the years as a result of deposition of diatoms that bloomed in the lake each spring and died in the summer. The leaf fossils are most beautiful in the fragile shale. This matrix contains a nice Alder leaf in an aesthetic display; there is also a poorly preserved insect.

The McAbee Fossil Beds site is a Konservat-Lagerstätten owing to the exceptional preservation of the flora and fauna. The fossils are the most diverse known in British Columbia for plants and insects of the Eocene. Only a small fraction of the diversity has yet to be formally described. Some 76 plant genera are known so far. The fossil site was recently acquired by the British Columbia provincial government and declared a heritage site. As a consequence, specimens like this that were collected from before the declaration will become increasingly in demand as no further material will be available.

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 .