Name:   Equisetites sp. Age:  Eocene Formation:  Green River Location:  Douglas Pass, Colorado Size:  Plant is 3.0 inches long. This is an excellent specimen of Equisetites sp. from the Green River Formation of Colorado. It is very easy to see that this specimen is directly related to the modern-day Equisetum. This horsetail rush is very well preserved and exhibits great detail. The individual joints or nodes are nicely displayed. It even shows the branching pattern, which is highly unusual. The fossil has great color and contrast. It is well positioned on the natural block of oil shale. This is a wonderful example of a horsetail rush from the Eocene.