Here is a two-for-one fossil: two different species preserved along the same bedding plane of a chunk of feldspar-rich shale from the Middle Eocene Ione Formation, western foothills of the Sierra Nevada. At top is an undescribed fossil leaf--Note the well-preserved midrib (primary vein) , secondary veins, elongated petiole (stem) and the margin; venation is pinnate, the leaf margin entire--that is, the edge of the fossil is smooth and non-serrated. Paleobotanists should be able to identify this specimen, eventually. Reddish-brown coloration is due to the presence of the mineral iron oxide, which formed during Eocene times in a semi-tropical, humid, chemically reducing paleoenvironment.
At bottom is a fragment of a fossil climbing fern, called Lygodium kaulfussi, from the Middle Eocene Ione Formation, western foothills of the Sierra Nevada, California; reddish coloration is also caused by iron oxide residues in the rocks; you are looking at two preserved lobes of a three to five-lobed species. Lygodium kaulfussi is most closely related to the living climbing fern, Lygodium palmatum, which is the only species of the genus Lygodium native to North America--it has been recorded from Mississippi, Alabama, and Georgia north through New England. The roughly 45 million-year-old specimen came from an extraordinarily rich locality on private property in Amador County--a specific site currently under formal paleobotanical study by Dr. Jack A. Wolfe (retired member of the United States Geological Survey) and Howard E. Schorn (retired Collections Manager of Fossil Plants at the University California Museum of Paleontology in Berkeley), among others, who hope to use the fossils to help approximate the paleoelevation of the ancestral Sierra Nevada region during the geologic past. Along with the Eocene Clarno Formation of Oregon, this specific fossil site yields the only known common to abundant Lygodium climbing fern fossils west of the Rocky Mountains region of the United States. Scattered, rare occurrences have been reported from select few localities in California, but only those Lygodium specimens collected from the site under study in Amador County have found their way to a museum. Hence, the Lygodium fossils from the Amador County locality are the only known fossils of climbing fern, collected in California, presently residing in a museum.
Please note: All fossil localities in the Ione Formation of Amador County, California, presently occur on private property; explicit permission from the land owners must be secured before collecting fossils there.