Fossils of Sequoiadendron chaneyi have been described from the Middle Miocene floras found in the area of Middlegate Basin in Churchill County, Nevada. The area of the Middlegate basin is preserved as the Middlegate and Eastgate Formations, which grew along the shores of an ancient lake.[3] While S. chaneyi is found in both formations, it is much rarer in the Middlegate formation, which was a south-facing scrubland-type ecosystem, being represented by only a few twiglets with foliage. In contrast, S. chaneyi is abundant in the Eastgate formation, which was a north-facing forested setting of hills and valleys, being represented by abundant foliage and several cones. Specimens figured as Glyptostrobus by Jack Wolfe in 1964 from the Middlegate basin were re-identified by Daniel Axelrod in 1985 as S. chaneyi, based on morphology and the presence of cones in the same deposits.[3]
Fossils of S. chaneyi have been found in the late Miocene Relief Peak Formation of Alpine County, California.[4] The fossils are found in the topmost section of the Relief Peak Formation at the contact of the formation and the Mount Reba Conglomerate. The stratigraphy and composition of formations indicate that the fossils of the Mount Reba flora were deposited in a low, broad valley environment that drained southwesterly and was exposed to the storm track. While present in the flora, S. chaneyi was a very rare component of it, being known from only three foliage specimens. The specimens were most likely transported downstream from the site where the trees were growing.[4]
S. chaneyi is known from the Middle Miocene Chloropagus Formation deposits of Storey County, Nevada, west of Fernley.[5] While the fossils are locally abundant at several of the Purple Mountain flora sites, it is found as a component at most of the sites. The higher concentrations seem to be associated with those deposits which were formed in mesic bottomlands.[5]
