PICEA DIETTERTIANA,A NEW SPECIES OF PETRIFIED CONES FROM THE OLIGOCENE OF WESTERN MONTANA

Fossils described in this treatment are the first structurally-preserved ovulate cones of Picea to be reported from the Tertiary. They are 5.0-5.8 cm long and 1.6-1.8 cm at their widest diameter. Numerous ovuliferous scales are arranged spirally around the axis and each bore two winged seeds. The bract subtending the scale is 4.0-7.0 mm long and is fused to the scale for 1.0 mm. The base of the bract is inflated on the abaxial side extending for about 1.0 mm between the seeds of the adjacent scales. Both the scales and their subtending bracts are recurved at their point of divergence from the axis. The ovuliferous scales taper gradually to a point, and the thickness of the tissues at the scale apex indicates that they were woody. Anatomically, the silicified cones are very similar to those of the Recent species and indicate that all important features of the latter had evolved by Oligocene time.