The Rhizopalmoxylon (petrified palm roots) species from the hills west of Redmond, Utah were originally reported as from the Jurassic Arapien Shale. However, the Utah State Geologic Map upon which this was largely based is erroneous, and the strata containing the palm roots are in the Tertiary Dipping Vat Formation, rather than in the Jurassic Arapien Shale. From the palm roots previously reported, three new species have been identified: Rhizopalmoxylon behuninii, R. blackii, and R. scottii.
Specimens of the new species, Palmoxylon gustavesonii, were collected from the Dipping Vat Formation east and south of Redmond. This formation unconformably overlies the Arapien Shale in the vicinity of the previously reported Jurassic palms. At the present time, the palm axes reported from the Arapien Shale cannot be conclusively demonstrated to have come from the Dipping Vat Formation. However, the presence of another species of petrified palm in the Dipping Vat Formation is sufficient to cast doubt on their existence in the Arapien Shale.
Tidwell, William D.; Medlyn, David A.; and Thayn, Gregory F.
"Fossil palm materials from the Tertiary Dipping Vat Formation of central Utah,"
Great Basin Naturalist: Vol. 32
, Article 1.
Available at: http://scholarsarchive.byu.edu/gbn/vol32/iss1/1