Because of the lack of dates from the northern region, all volcanic ashes will be evaluated for their dating potential, and selected ones will dated. Recent micropaleontological work at Dinosaur NM and elsewhere on the Colorado Plateau has yielded preliminary paleontological age determinations. This work has focused on fossil pollen, spores, charopytes and ostracodes. Reconnaissance work has revealed that these microfossils are also present in the northern part of the Morrison basin. Therefore, favorable horizons in this area will be sampled for similar analyses.
Paleoclimatic inferences provide broad and important constraints on ecosystem reconstruction.
Some rock types are indicators of paleoclimate and the distribution of these rock types can be useful in reconstructing the Morrison paleoclimate. These climatic indicators can be used to evaluate changes in climate through time, which may be cyclical and predictable, as well as latitudinal variations in climate at any given time in the rock record. The Morrison Formation contains all of these rock types, in addition to stream and overbank deposits. Another approach to paleoclimate is through reconstruction of the ancient landscape on a large scale. Paleolatitude, determined by paleomagnetic studies already available in the literature, can be combined with paleotopographic reconstructions, drainage patterns, and wind directions, to determine such things as rain shadow effects and latitudinal variations in paleoclimate.