Acutipuerilis and other non-lithistid sponges from the early Silurian of the Southern Urals, Russia

Abstract

ABSTRACT Despite the recent discovery of abundant and diverse latest Ordovician sponges in China, early Silurian sponges are generally scarce, and non-lithistid, spiculate sponges remain poorly known. This is particularly true outside of a few well-studied regions, and monographic biases strongly influence the published record of the group. A new, well-preserved example of the spinose reticulosan Acutipuerilis from the Silurian of the southern Ural Mountains represents the first such fossil from this region and the first post-Ordovician asthenospongiid. Hexaradiate heteractinid spicules assigned to Toquimiella? sp. co-occur in the same rocks with fragments of other reticulosans including the reticulosan Plectoderma? sp., but no other fully articulated remains have been found. These three genera were previously known only from their type localities in Laurentia and Avalonia, in different environments, and the remarkable co-occurrence here raises the possibility of a change in sponge ecology and distribution following the Hirnantian Extinction.