Vertebrate diversity reveals perturbations in faunal communities prior to the Hangenberg event in the Montagne Noire (France)

The Hangenberg crisis represents a mass extinction marked by a biodiversity turnover at the Devonian-Carboniferous boundary. However, the last million years before this dramatic event have been poorly investigated. Here we report new data on the size and abundances of vertebrate remains as well as carbon isotope data from the latest Famennian in the Montagne Noire (France). A significant decrease in fish abundance and a general reduction in the size of vertebrate remains are observed during a period of stable environment before the onset of the Hangenberg crisis. No perturbations are recorded by the carbon isotopes, supporting the stability of the environment. This significant change in the structuration of vertebrate communities prior to the Hangenberg crisis is not linked to any turnover in other faunal groups. That could be interpreted as changes in faunal repartition that predate mass extinctions.

Automated summary

The Hangenberg crisis represents a mass extinction event at the Devonian-Carboniferous boundary. New data from the latest Famennian in France shows a decrease in fish abundance and a reduction in the size of vertebrate remains during a stable environment period before the crisis. There were no perturbations recorded by carbon isotopes, indicating environmental stability. The significant change in vertebrate community structure prior to the Hangenberg crisis is not linked to turnover in other faunal groups.