| Here is the youngest fossil foliage from a Giant Sequoia (Sequoiadendron chaneyi Axelrod) yet discovered in the geologic record--it came from an unnamed rock formation roughly 4.8 to 5.1 million years old (early Pliocene in geologic age) near Minden-Gardnerville in Douglas County, western Nevada. During the Miocene, Giant Sequoia was rather widespread throughout the ancestral Great Basin region of Nevada, occurring at a number of famous Middle Miocene (roughly 16 to 11 million years old) fossil plant localities, such as Middlegate, Purple Mountain , Aldrich Station, Chalk Hills and Fallon. Today, Giant Sequoia is restricted to a narrow, moist belt along the western slopes of the Sierra Nevada in California; it tends to occur in rather isolated pockets, called groves, where environmental conditions favor its persistence--most notably at Sequoia National Park east of Fresno. The specimen shown here (part and counterpart of the same specimen on two different pieces of shale; in actual size, the pieces of shale shown in the images are roughly 10 centimeters, or 4 inches across) is the youngest foliage known from Big Tree in the fossil record (pollens from Sierra Redwood have been identified from younger sedimentary formations, such as the Coso Formation in Inyo County, California, at roughly 3 million years old). Also present on the matrix is a fossil leaf from a new species of evergreen live oak--identified by paleobotanist Howard Schorn--that is very closely related to the huckleberry oak, Quercus vaccinofolia, a variety now native to the Sierra Nevada and Cascade ranges of California and to the Siskiyou and North Coast Ranges of northern California and southern Oregon. The fossils reside on a slab of diatomaceous mudstone collected in early July 2001 by Dr. Diane Erwin--Collections Manager of fossil plants at the University California Museum of Paleontology (in Berkeley, California) from an isolated outcrop in the Pine Nut Mountains of Douglas County, Nevada. The specimens are now under formal paleobotanical study by Dr. Erwin and Howard Schorn (retired Collections Manager of Fossils Plants at UCMP). The first specimens of fossil giant sequoia foliage from this particular locality were collected by Howard Schorn in the 1990s. |