ANCIENT SPIDERS AND SALT LAKES

The Green River Formation crops out over 25,000 square miles of Wyoming, Colorado, and Utah, averages 2000' in thickness, and represents one of the world’s longest-lived Great Lakes systems, lasting approximately 17 million years. Spider fossils are abundant in some horizons but, until recently, only a single specimen (Linyphia byrami Cockerell, 1925) had been described. In the first part of this talk, a sample of spiders from the families Uloboridae, Hersiliidae, Selenopidae, and Thomisidae are described. Such diversity represents a variety of life modes, and habitats; it is suggested that storms and flash flooding were the likely mechanisms for transporting the spiders into the lake. In the second part of this talk, we compare the spider fauna of Green River with those of two other paleolake deposits, and demonstrate how spider leg flexure can serve as a proxy for the paleosalinity of ancient lakes.