The term Toarcian turnover, alternatively the Toarcian extinction, the Pliensbachian-Toarcian extinction, or the Early Jurassic extinction, refers to the wave of extinctions that marked the end of the Pliensbachian stage and the start of the Toarcian stage of the Early Jurassic period, c. 183 million years ago.
The Toarcian turnover was most strongly manifested in aquatic lifeforms, notably in mollusk groups like ammonites. Its reach was global in extent, as evidenced by research in European (peninsula of Peniche, Portugal) and Japanese waters, the Andean basin, the floor of the former Tethys Sea. Evidence points to anoxic bottom waters as the probable cause of these marine extinctions, linked in turn to the massive volcanism of the Karoo-Ferrar eruptions in the relevant era. The Toarcian turnover was the seventh-largest mass extinction in Earth's history.
- Wignall, Paul B., and Anthony Hallam. Mass Extinctions and Their Aftermath. Oxford, Oxford University Press, 1997; pp. 164-5
- Location Archived 2013-06-29 at Archive.is
- Calcareous cliffs of Peniche peninsula (west coast of Portugal): geological heritage inventory and characterization - paper by A. R. Rilo, L. V. Duarte, and A. Tavares (in Portuguese, with abstract in Spanish and English)
- The Evolution of the Coastline at Peniche and Berlengas Islands – article by Teresa Azevedo, and Elisabete Nunes
- MacLeod, Kenneth G., and Christian Koeberl. Catastrophic Events and Mass Extinctions: Impacts and Beyond. Boulder, CO, Geological Society of America, 2002; pp. 525-9.
- Marti, Joan, and Gerald Ernst. Volcanoes and the Environment. Cambridge, Cambridge University Press, 2005; p. 219.
- Volcanic eruptions once caused mass extinctions in the oceans – could climate change do the same?
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