Paper No. 301-10
Presentation Time: 9:00 AM-6:30 PM
UNEXPECTEDLY DIVERSE CRINOID FAUNA FROM SVALBARD IN THE AFTERMATH OF THE END-PERMIAN MASS EXTINCTION
The end-Permian mass extinction constitutes the major breakdown in the history of life. With regards to crinoids (Crinoidea), it led to the demise of the major Paleozoic crinoid groups including cladids, disparids, flexibles and camerates. It has been argued that only a single lineage derived from a Late Paleozoic ancestor survived this mass extinction. Holocrinids (Holocrinida), the oldest Mesozoic crinoids, are considered the stem group for the post-Paleozoic monophyletic subclass Articulata. New findings of crinoids from the Lower Triassic (Induan and Olenekian) of Svalbard radically reassess the previous hypothesis about the severity of the end-Permian mass extinction on crinoids and provide new insights into the origins and early evolution of post-Paleozoic crinoids. More specifically, we show that at least several taxa belonging to at least four orders already existed in the Early Triassic of Svalbard. This implies that the aftermath recovery of crinoids should have begun much earlier in higher paleolatitudes than in central Tethys. It seems highly improbable that such a rapid rate of morphological divergence from a single holocrinid lineage could have taken place within few Myrs following the P/T boundary. More probably, the divergence of the crown-group articulates could have likely occurred in the Late Paleozoic implying the survival of more than a single crinoid lineage from the end-Permian extinction.