Crinoids from Svalbard in the aftermath of the end−Permian mass extinction

Abstract

Abstract:The end−Permian mass extinction constituted a major event in the history of cri− noids. It led to the demise of the major Paleozoic crinoid groups including cladids, disparids, flexibles and camerates. It is widely accepted that a single lineage, derived from a late Paleo− zoic cladid ancestor (Ampelocrinidae), survived this mass extinction. Holocrinid crinoids (Holocrinus, Holocrinida) along with recently described genus Baudicrinus (Encrinida), the only crinoid groups known from the Early Triassic, are considered the stem groups for the post−Paleozoic monophyletic subclass Articulata. Here, we report preliminary data on unex− pectedly diverse crinoid faunas comprising at least four orders from the Lower Triassic (Induan and Olenekian) of Svalbard, extending their stratigraphic ranges deeper into the early Mesozoic. These findings strongly imply that the recovery of crinoids in the aftermath of the end−Permian extinction began much earlier at higher palaeolatitudes than in the central Tethys.

Boreal earliest Triassic biotas elucidate globally depauperate hard substrate communities after the end-Permian mass extinction

“…The recovery of lower tier, skeletonised biotas was therefore evidently delayed in comparison to soft-bottom communities313262, a phenomenon that we show manifested simultaneously within both low, and mid-high palaeolatitude assemblages. Certainly, some filter feeding organisms such as crinoids seem to have re-diversified earlier in the Boreal Realm (at least after the latest Induan A. fassaensis bivalve zone equivalent63), yet typical encrusters including cyclostome bryozoans and serpulid polychaetes did not fully re-establish until the Rhaetian64. This conspicuous underrepresentation – which is likely not taphonomic because Palaeozoic encrusters possessed similar calcitic skeletons65 and cemented to the substrate throughout the sessile phase of their life cycle – accords with extreme fluctuations in oceanic salinity66, de-oxygenation94067, intense weathering and run-off that are thought to have promoted widespread eutrophication and the proliferation of stromatolite-forming microbial substrates10112668 in the absence of mat-grazing organisms5569.…”

New data from Oman indicate benthic high biomass productivity coupled with low taxonomic diversity in the aftermath of the Permian–Triassic Boundary mass extinction

“…in Svalbard (Salamon et al . ) and was assigned to Holocrinidae, Encrinidae, Ainigmacrinidae and Roveacrinida predating the origin of the latter three clades to the Early Triassic. It was concluded that crinoid diversification began earlier in boreal realms than in the tropics.…”

“…In the boreal realm, a silicified community of late Griesbachian and Dienerian crinoid sclerites has been recovered from the Vardebukta Fm. in Svalbard (Salamon et al 2015) and was assigned to Holocrinidae, Encrinidae, Ainigmacrinidae and Roveacrinida predating the origin of the latter three clades to the Early Triassic. It was concluded that crinoid diversification began earlier in boreal realms than in the tropics.…”

Early Triassic benthic invertebrates from the Great Bank of Guizhou, South China: systematic palaeontology and palaeobiology

“…) and Festningen, Svalbard (Salamon et al . ). The occurrence of Holocrinus on the Great Bank of Guizhou and in western Zhejiang (Chen et al .…”