The rove beetle fossils of the Green River Formation! Stylianos Chatzimanolis" Department of Biological and Environmental Sciences, University of Tennessee at Chattanooga, " 615 McCallie Ave., Dept. 2653, Chattanooga, TN 37403! ! Introduction! Results! ! The Green River Formation is a system of Eocene Examination of more than 10,000 fossiliferous lakes located near the present day borders of rocks over a period of three weeks produced 354 Wyoming, Colorado and Utah. Over the past 150 specimens of rove beetles. A preliminary account years, there have been several astonishing of those revealed the presence of eight subfamilies vertebrate discoveries from these fossil beds, and at least 25 new species (see Table below) in including crocodiles, boa constrictors, numerous addition to the specimens described before by fish and the earliest known bat (Nuds and Selden Scudder.! 2008). The flora of the area has also been studied in detail (MacGinitie 1969) showing that cut-tails, ! palms and sycamores were common. However, the insect fauna remains relatively neglected with Subfamily! Species Specimens hundreds of species awaiting description.! ! Aleocharinae! Many Many Two elements make the Green River Formation Omaliinae 2 3 fossils exciting: a) the limestone matrix is very fine ! and allowed for the preservation of minute details Oxytelinae! 6+ 27 of these fossils and b) the already described fossils support the hypothesis that the climate of Fig. 2 Staphylinites obsoletum Scudder! Fig. 3 Lathrobium abscessum Scudder! Fig. 4 Steninae! Paederinae! 8+ 94+ North America was much warmer 48 million years ago than it is today. The abovementioned fossils Pselaphinae! 2 2 point to a moist subtropical climate with average Staphylininae 4+ 10 annual temperatures ~4°C higher than today. ! ! ! Steninae 1 1 Until now, only seven rove beetles have been ! described from the Green River Formation. These Tachyporinae 2 2 fossils were described by Scudder (see Scudder ! 1890 for a review) and include two Aleocharinae ! (Gyrophaena saxicola, Homalota recisa), two Oxytelinae (Bledius adamus, Oxytelus pristinus), Discussion – Future work ! one Staphylininae (Leistrotrophus patriarchicus), ! one Paederinae (Lathrobium abscessum) and The Green River Formation is one of the most Staphylinites obsoletum as insertae sedis. Almost speciose rove beetle Lagerstätte in N. America all of these species are taxonomically misplaced with several species represented by numerous and perhaps some do not belong in Staphylinidae. ! specimens. The fine limestone matrix allowed the ! preservation of minute morphological details that The objective of this study is to describe the made species level identification of most of these rove beetle fauna of the Green River formation. fossils possible. Preliminary analyses indicate that Further analyses will examine whether the some fossil taxa appear more closely related to temperature difference between Middle Eocene Fig. 5 Cryptobiina (Paederinae)! Fig. 6 Pinophilini (Paederinae)! Fig. 7 Pinophilus? (Paederinae)! species currently inhabiting the tropics than and present had a significant impact on the species inhabiting N. America. Additionally, several fauna of N. America.! fossil species are much larger in size than congeneric taxa found in N. America. Further analyses are required to examine how many of these taxa are still present in N. America at the generic level and where their closest relatives live.! ! Materials and Methods! ! Fossil specimens were examined in the Smithsonian Institution and the Museum of Comparative Zoology (Harvard). Fossils were photographed with a Visionary Digital Passport system and photographs were auto-montaged using Helicon Focus 4.2.7.! Geological Setting The formation is composed of several layers of lacurstine limestone and oil shales. Almost all of the insect fossils studied came from the Literature cited! Piceance Creek Basin and are approximately 48 million years old Grande, L. 1980. Paleontology of the Green River Formation with a review of ! (Hail and Smith 1997). ! !the fish fauna. The Geological Survey of Wyoming Bulletin 63: !1-333.! ! Hail, W. J. Jr and M. C. Smith. 1997. Geology of the Southern Part of the ! !Piceance Creek Basin, Northwestern Colorado, IMAP 2529. United !States Geological Survey, Washington, D.C.! MacGinitie, H. D. 1969. The Eocene Green River flora of northwestern !Colorado and northeastern Utah. University of California Press, 1– !204.! Nudds, J. R. and P. A. Selden. 2008. Fossil ecosystems of North America. A Fig. 8 Quedius (Staphylininae)! Fig. 9 Quediina (Staphylininae)! !guide to their sites and their extraordinary biotas. The University of !Chicago Press, 1-288 pp.! Scudder, S.H. 1890. The tertiary insects of North America. Report of the !United States Geological Survey of the Territories 13: 1–734.! ! Acknowledgments! Financial support was provided by a UTC Foundation Research Grant and NSF DEB-0741475 (to S. Chatzimanolis and M.S. Engel). I thank Conrad Labandeira, Marsh Finnegan, Dale Greenwalt and Phil Perkins for their assistance and hospitality during my visit at the Smithsonian Institution and the Museum of Comparative Zoology at Harvard University. For further information! Please contact Stylianos Chatzimanolis at [email protected] More information on this and related projects can be obtained at Fig. 1 Locality map showing the Green River Formation ! www.staphylinini.org outcrop (modified from Grande1980).! Fig. 10 Oxytellinae! Fig. 11 Omaliinae! Fig. 12 Tachyporini (Tachyporinae)! .