Two intriguing pluricolumnals (Crinoidea) from the Lower Palaeozoic of Powys and Shropshire

Complete fossils must be preferred to fragments for most palaeontological studies, but disarticulated specimens are nonetheless potential sources of noteworthy data. Two crinoid pluricolumnals are recorded from the lower Palaeozoic; informed discussion shows each is a basis for palaeobiological interpretation. Both are gracile and are probably belong to disparids. Floricrinus (col.) sp. is from the Silurian of Wenlock Edge, Shropshire, either from the Much Wenlock Limestone Formation (Wenlock) or, more likely, the Lower Elton Formation (Ludlow). This is the first crinoid from the Silurian of the British Isles with a pentapetaloid arrangement of the areola, a geometry common in the Middle-Upper Ordovician and higher in the geologic column. Pluricolumnal gen. et sp. indet. is from the Lower Llanvirn of Powys. One end of the otherwise straight specimen is tightly coiled. This is likely the proxistele, the most flexible region of the column, and the coiling occurred after the crown was lost by autotomy in response to an environmental disturbance. (C) 2020 The Geologists' Association. Published by Elsevier Ltd. All rights reserved.

Automated summary

Complete fossils are generally preferred over fragments for most palaeontological studies, but disarticulated specimens can still provide valuable data. Two crinoid pluricolumnals from the lower Palaeozoic are discussed, offering insight for palaeobiological interpretation. These gracile specimens are likely disparids, with one being from the Silurian of Wenlock Edge and the other from the Lower Llanvirn of Powys.