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

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.

KEYWORDS:

• Porifera
• phylogeny
• mass extinction
• Reticulosa
• Heteractinida

Acknowledgements

The specimen was collected and kindly donated by R. Ch. Tagarieva. Rustem Yakupov acknowledges the support of the Russian State program, grant no. 0246-2019-0118. The manuscript was enhanced by helpful comments from Christian Skovsted (editor) and two anonymous referees.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Russian State program under Grant 0246-2019-0118.