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How important were Angiosperm plants and mammal dung for the evolution of beetles, shows a study newly published in the Proceedings of the Royal Society. Based on DNA sequences Dr. Dirk Ahrens and Dr. Julia Schwarzer from the Zoological Research Museum A. Koenig Bonn and their colleague Prof. Alfried Vogler from the Natural History Museum London reconstructed a phylogeny of Scarab beetles, which include stag beetles, dung beetles and chafers. The researches dated the different lineages using the fossils of the group.
The evolution of the plant feeding cock chafers and allies, which are one of the most diverse beetle groups in the world, followed almost immediately thediversification of the Angiosperms from the Middle Cretaceous. This group of beetles also survived the impact of the meteorite, that exstinguished the Dinosaurs. Dung beetles originated instead much later after the success of the mammals, and in particular of the even-toed ungulates (Artiodactyla), which were thyemselfes promoted by the evolution of Angiosperms but also by the extenpansion of steppes and savannas in Miocene. Based in the timing of their evolution, the reserach consider the hypothesis little likely that early dung beetles fed on Dinosaur dung. How promising the new ressources were showed the several independet origins of herbivory and dung feeding among the Scarab beetles.
However, the reserachers still try to unravel the mystery, why there are so many species of species. In contrast to other plant feeding insects they are not specialised on certain plant species. They think that it is possible that the revolution of soil litter initiated by the success of the much more productive angiosperms offered in short time much more suitable conditions for these beetles.
Ahrens, D., Schwarzer, J. & Vogler, A.P. (2014) The evolution of scarab beetles tracks the unfolding rise of angiosperms and mammals. Proceedings of the Royal Society B 2014 281, 20141470
Eberle, J., Myburgh, R. & Ahrens, D. (2014) The evolution of morphospace in phytophagous scarab chafers: no competition - no divergence? Plos One 9 (5): e98536.