Theriosynoecum Wyomingense (Branson, 1935), a Possible Guide Ostracode to the Salt Water Mash Member of the Morrison Formation

The ostracode species Theriosynoecum wyomingense (Branson, 1935) appears to be restricted to the Salt Wash Member of the Morrison Formation in the Colorado Plateau area and to equivalents of the Salt Wash Member in lithologically undifferentiated sedimentary rocks in Wyoming, South Dakota, and Montana. Associated charophytes tend to support this hypothesis.