Date of Award
Master of Science (MS)
Michael E. Nelson
The middle Eocene Powder Wash local fauna from northeastern Utah is found in a moderately sorted, very fine quartz sandstone that was deposited along the shore of ancient Lake Uinta. Settling experiments with recent bones of similar size show that the bones behaved as larger particles than the grains of the enclosing sediment. In place measurements of bone orientation show the total sample of bones has a random orientation. Subpopulations of bones based on size are oriented perpendicular to the ancient shoreline and are parallel to each other but plunge in opposite direction, with the larger ones plunging towards the land and the smaller bones plunging away from it. Current from an incoming stream, runoff from shore, or swash and backwash on the beach produced the orientations. Most fossils are completely disarticulated and fragmentary; however, the preservation of delicate features, such as lizard teeth and the slender roots and pointed cusps of mammal teeth, suggest that mechanical abrasion was not a factor in pre-burial damage. The fossil accumulation probably represents a coprocoenosis, formed by the accumulation of carnivore scat and avian predator pellets. Many biases, especially those introduced by the activities of carnivores, make the paleoecological interpretation of a coprocoenosis difficult.
Copyright 1978 Dale M. Gnidovec
Gnidovec, Dale M., "Tophonomy of the Powder Wash Vertebrate Quarry, Green River Formation (Eocene), Uintah County, Utah" (1978). Master's Theses. 1702.