Nematode fossil trails from the Green River Formation (Eocene) in the Uinta Basin, Utah

Abstract

Wavelike trails that are interpreted as nematode trails occur in large numbers at two stratigraphic horizons in the Green River Formation (Middle Eocene) in the western part of the Uinta Basin, Utah. One horizon is in the lower part of the delta facies in the Soldier Summit area and the other is in the upper part of the Parachute Creek Member or the lower part of the Evacuation Creek Member in upper Timber Creek in Wasatch County, Utah. The interpretation that those fossil trails were made by nematodes is based on the fact that nematodes are the only recent organisms known to make sinusoidal trails of the same size and form. If this interpretation is correct, these occurrences represent an interesting and a most unusual record of an entire animal phylum which is virtually un- known in the fossil record.