Cyanobacteria and seasonal death: A new taphonomic model for the Eocene Messel lake

Two new observations lead us to reconsider the taphonomy of Messel. First, several horses as well as turtles indicate death at a specific season although they come from different horizons. Second, specific structures in the Sediments are very similar to those found in Neumark-Nord. There they could be related to Cyanobacteria. Blooms of Cyanobacteria may poison die surface water. From actual observations it is known that animals drinking such poison water collapse immediately and die mostly near or within the water soon. This model might explain why birds and bats are so frequent throughout the entire profile of Messel. Both drink from the water surface during flight. In contrast to volcanic exhalations, assumed so far, such algae blooms occur repeatedly and always during early summer and autumn. An erratum to this article is available at .