Hangenberg event
The Hangenberg event is a bioevent that occurred at the end of the Famennian stage associated with the Late Devonian extinction ; it was an anoxic event marked by a black shale. It has been proposed that this was related to a rapid sea-level fall due to the last phase of the Devonian Southern Hemisphere glaciation. It has also been suggested that it was linked to an increase in terrestrial plant cover, leading to increased nutrient supply in rivers. This may have led to eutrophication of semi-restricted epicontinental seas and could have stimulated algal blooms.
It is named from the Hangenberg Shale, part of a sequence that straddles the Devonian-Carboniferous boundary, from the Rhenish Massif in Germany.
Following the extinction, vertebrates experienced reduced body size for the following 36 million years, at least in part because smaller taxa diversified more successfully.
