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RESEARCH PRODUCT

Biogeography of Triassic ammonoids

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After the end-Permian mass extinction, ammonoids experienced an explosive recovery followed by episodes of radiation and extinction. These events were associated with sudden biogeographic changes often closely related to major climatic and oceanographic changes. Previous biogeographic studies of Triassic ammonoids have rarely focused on a specific time-interval and were rarely based on quantitative methods. Thus, we will first review biogeographical methods and the biogeographical signals known from Triassic ammonoids. Secondly, we will focus on quantitative approaches that improve our knowledge of ammonoid biogeographical structuring and dynamics during the Triassic, and we will discuss controlling factors such as Sea Surface Temperature and oceanic circulation. We show that a biogeographical latitudinal structuring of faunas persisted along the eastern Panthalassa during the Ladinian, as a marked differentiation between Tethys and Panthalassic realms. Biogeographical configurations of the Carnian, Norian and Rhaetian appear more homogeneous, although a weak latitudinal structuring may have continued up to the late Carnian.