Biodiversity of bugs (Heteroptera) from the Eocene Messel pit (Germany), from Green River (USA) and from other Paleogene fossil sites, with an analysis of their biogeographic significance
Final Report Abstract
The history of insect biodiversity and the process of its evolution during the Cenozoic are still largely unknown. The same applies for many questions concerning the historical biogeography of insects and possible interrelationships between climate change and biogeographic diversity patterns. In this study, heteropteran insects (Insecta: Heteroptera) are taken as a showcase for illuminating differences and similarities of biodiversity in different Eocene fossil sites. The project focused on the investigation of the biodiversity of Eocene Heteroptera, with emphasis on the faunas from Messel (Germany) and Green River (USA). The current investigations indicate that the biodiversity of Heteroptera in Messel seems to be higher than in Green River, and until now there are relatively few similarities on low systematic level. A comparative survey of the “morphotypes” in Messel and Green River is still ongoing. Certain groups including lace bugs (Tingidae), flat bugs (Aradidae) assassin bugs (Reduviidae), and stink bugs (Pentatomidae) have been investigated more extensively, and they are, with one exception, very different in the two taphocoenoses. Lace bugs (Tingidae) are found comparatively often in Messel, but rare in Green River. For Messel, at least one additional species can be added to the already described lace bugs, and the variability of the described species can be assessed on the base of about 50 fossil specimens. From Green River, four fossil specimens of lace bugs could be found, which show an extremely enlarged last antennal segment. These specimens will be described as new genus and species, and refine our understanding of tingid evolution and behaviour. The flat bugs (Aradidae) from Messel are very diverse, three new species have been described in this project. Especially well-represented in Messel are members of the subfamily Mezirinae that today occur in all major biogeographic regions but seem to be concentrated in the Southern Hemisphere. Comparison of the portions of subfamilies of aradid taphocoenoses in amber and in lacustrine sediments raise questions concerning the composition of the former fauna. No flat bugs are recorded from Green River. For the reduviids, there might emerge novel biogeographic relationships of certain subgroups in comparison with their extant relatives. The new fossil records from Messel and Green River indicate that during the Eocene, certain groups had a wider distribution than they have today, and that their extant distribution is relict. The same applies for a very enigmatic group of stink bugs (Pentatomidae) which occur in both Messel and Green River. They show an exaggerated spiny morphology, and the fossils from both sites are closely related, perhaps even conspecific. Possible phylogenetic relationships with exotic extant groups which would indicate strongly disjunct distributions are still under investigation. Several studies have shown this for other insect taxa, but investigations for Heteroptera on this topic are still very rare. The strongly varying biogeographic connections support the assumption that the warm and much more equable Eocene climate formerly allowed a much wider distribution of many insect groups. This is often neglected in biogeographic analyses of extant insects that base their assumptions on the extant distributions only. More analyses of fossils are necessary to address this lack of information. Synchrotron radiation tomography was applied to bug fossils from Messel at the Swiss Light Source (SLS) at the Paul Scherrer Institut in Villigen, Switzerland. Unfortunately the datasets of the Messel fossils were nearly impossible to reconstruct, because there is no evident difference between the fossil and the very organic rich oil shale matrix.
Publications
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(2010). Biodiversity of bugs (Insecta: Heteroptera) from the Messel pit and other fossil sites. In: Hoppe, A., Röhling, H.-G., Schüth, C. (eds.): GeoDarmstadt2010-Geowissenschaften sichern Zukunft, Geosciences secure the future. 10. bis 13. Oktober 2010. Schriftenreihe der Deutschen Gesellschaft für Geowissenschaften 68, 594-595
Wedmann, S
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(2011). Fossil bugs (Insecta: Heteroptera) of Messel and the Green River Formation (USA) – Are there any connections? p. 89-90. In: Lehmann, T. & Schaal, S.F.K. (eds.) (2011). The World at the Time of Messel: Puzzles in Palaeobiology, Palaeoenvironment, and the History of Early Primates. 22nd International Senckenberg Conference. 15th – 19th November 2011, Frankfurt am Main. Conference Volume. Senckenberg Gesellschaft für Naturforschung, Frankfurt am Main, 203 pp.
Koch, M., Wedmann, S., Labandeira, C., Hamlin, J.
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(2011). New studies on assassin bugs (Insecta: Heteroptera) from Messel (Germany). Beiträge zur Paläontologie 32: 15
Koch, M. , Wedmann, S.
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(2012). 47 Ma old true bugs (Insecta: Heteroptera) – do they have connections with extant ones? p. 94-95. In: Witzmann, F. & Aberhan, M. (eds.): TERRA NOSTRA, Schriften der GeoUnion Alfred-Wegener-Stiftung 2012/3: Centenary Meeting of the Paläontologische Gesellschaft 24.09. – 29.09.2012, 242pp. Publisher GeoUnion Alfred-Wegener-Stiftung, Berlin, ISSN 0946-8978
Koch, M. & Wedmann, S.
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(2013). Unusual fossil lace bugs (Heteroptera: Tingidae) from Green River. p. 184. In: Reitner, J et al (Eds.): Palaeobiology and Geobiology of Fossil Lagerstätten through Earth History. A joint conference of the Paläontologische Gesellschaft and the Palaeontological Society of China, Göttingen, Germany, September 23-27, 2013, ISBN: 978-3-86395-135-1
Wedmann, S. & Wappler, T.
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(2014 online). New flatbug (Hemiptera: Heteroptera: Aradidae) records from the Middle Eocene Messel Maar, Germany. Paläontologische Zeitschrift
Wappler, T., Heiss, E., Wedmann, S.
