An Updated Review of the Fish Faunas From the Green River Formation, the World’s Most Productive Freshwater Lagerstätten

Abstract

The Green River Formation has provided what is clearly the richest, most diverse sample of Early Tertiary freshwater vertebrate faunas in the world (see numerous illustrations in , for example). In addition to a wide array of non-fish fossils, the formation provides an unparalleled sample of the Early Tertiary fish fauna of North America, with hundreds of thousands of beautifully preserved skeletons belonging to at least 16 different families. The composition, relationships, and importance of the Green River Formation fish faunas have become increasingly evident as detailed studies on these faunas continue. An earlier review by (, ) has been a commonly used identification guide to the fishes of the Green River Formation. It was written over 20 years ago when there were far fewer specimens, fewer detailed descriptions and almost no phylogenetic studies of Green River fish species together with other closely related fossil and living species. In light of progress since that earlier review, I believe that the time is right for a new synthesis. This paper provides an updated taxonomic assessment of the Green River fishes, summarizes recent works on them, and points out some remaining questions concerning various Green River taxa.