Silicified, upright axes of Palmoxylon are abundant in the Green River Formation in Eden Valley, Wyoming. Three new species of Palmoxylon, as well as the previously described Palmoxylon macginitiei Tidwell et al., were collected. These new species are P. edenense, P. contortum, and P. colei. They are compared to P. macginitiei and other anatomically similar Palmoxylon species. Palmoxylon edenense appears to be the most abundant species at this locality.
Tidwell, William D.; Medlyn, David A.; and Thayn, Gregory F.
"Three new species of Palmoxylon from the Eocene Green River Formation, Wyoming,"
Great Basin Naturalist: Vol. 33
, Article 1.
Available at: http://scholarsarchive.byu.edu/gbn/vol33/iss2/1