Toarcian Stage

Toarcian turnover

The Toarcian Age (183–174 Ma) is the fourth and last age in the Early Jurassic Epoch of the Jurassic Period of the Mesozoic Era. It occurs after the Pliensbachian Age, and before the Aalenian Age.

"During the Pliensbachian–Toarcian interval of the Early Jurassic, there is a well-known second order marine extinction that is observable at the species and genus levels. Ammonite diversity data from successions throughout Europe and parts of the Arctic suggest that this extinction may have been multi-phased with diversity declining over six separate intervals. The main-phase of decline begins at the Pliensbachian–Toarcian boundary and extends into the Lower Toarcian, to a level that is correlative with the Tenuicostatum/Serpentinum Zone boundary." (Caruthers, Smith, and Gröcke 2013)
Cooling coincided with a massive volcanic event, the North Sea Dome, which restricted the flow of seawater and the associated heat that it carried from the equator towards the North Pole region (Korte et al. 2015)
Large conifers and seed plants continue to dominate
An ambiguous plant from China, Nanjinganthus dendrostyla, referred to as the oldest known angiosperm, although many paleobotanists question the interpretation of these fossils.

Above: Figure 2 from Fu et al. 2018, showing fossils of Nanjinganthus

Above: Reconstruction of Nanjinganthus