Exploring the major depletions of conodont diversity during the Triassic

In this paper, we show that the Triassic fossil record reflects just two great depletions of conodont diversity before the Rhaetian, which occurred in the Smithian (Olenekian, Early Triassic) and in the Julian (Carnian, Late Triassic). By exploring this context, our results highlighted that they respond to different origination–extinction dynamics. Thus, while the Smithian diversity depletion can be interpreted as a consequence of elevated extinction, the Julian diversity depletion was triggered by fluctuations in origination regime. This evidence suggests that, despite the role of extinction on diversity losses, conodonts suffered crucial changes on the origination regimes during the Late Triassic which triggered these events. Notwithstanding, our results indicate that the end-Triassic diversity depletion of conodonts was produced by background extinction levels in a context of lower origination. This suggests that several biological factors, rather than a unique, environmental and/or cyclic cause, could have influenced the evolutionary history of conodonts during the Triassic.