Spirolites radwanskiin. igen. n. isp.: vermetid gastropod attachment etching trace from the middle Miocene rocky coast of the Paratethys, Poland

Abstract

A new ichnogenus and ichnospecies, Spirolites radwanskii, is a spiral boring recognized in large limestone clasts deposited in a Miocene cliff-foot ramp. It is characterized by a semi-circular or inverted Ω-shaped cross section, gradually increasing width, gradual entrenching in the rock from the narrower side, consistent coiling direction, steep margin from the wider side, two-order annuli, and occasional truncation of the narrower side by the wider part. It is interpreted as a boring of vermetid gastropods, similar to the recent Dendropoma. Spirolites co-occurs with the bivalve borings Gastrochaenolites, mostly G. torpedo, sponge borings Entobia, and the spionid polychaete boring Caulostrepsis, which are typical of the Entobia ichnofacies. Spirolites was produced in very shallow, clean and warm sea waters.

Palaeoecology and taphonomy of a middle Miocene domical cheilostome bryozoan, Siwa Oasis, the northern Western Desert of Egypt

“…9A, B). The morphological characteristics demonstrate strong similarity to Spirolites radwanskii Uchman et al., 2018. The authors interpreted this structure as the attachment etching (Fixichnia) of vermetid gastropod (Table 2).…”

“…Borings represent the most important and abundant features on the dome‐shaped cheilostome bryozoan colonies. Eight ichnogenera have been identified (Table 2; Figs 5, 6, 8, 9): Trypanites Mägdefrau, 1932, Maeandropolydora Voigt, 1965, Caulosterpsis Clarke, 1908, Gastrochaenolites (Leymerie, 1842), Spirolites Uchman et al., 2018, Renichnus Mayoral 1987, Centrichnus Bromley & Martinell, 1991, and Oichnus Bromley, 1981. The most common traces of bioerosion are those that were generated by annelids, particularly Trypanites .…”

“…(2010) and Uchman et al . (2018). Although taxonomic identification to ichnospecies level was possible for several specimens, the highly eroded dome‐shaped bryozoan colonies meant that in most cases specimens could only be identified to ichnogeneric level.…”

“…El Hedeny & El‐Sabbagh 2018; Uchman et al . 2018). The ichnotaxa associations indicate a shallow‐marine (<10 m water depth) low‐energy environment, with a low sedimentation rate and periods of non‐deposition (e.g.…”

“…For example, the ichnogenus Spirolites was dominated in very shallow, clean and warm sea waters (Uchman et al . 2018), vermetid gastropod (producer of Renichnus ) is predominantly a shallow‐water species (Jagt 2003), Caulostrepsis occurs in shallow‐water environments, in a water depth ranging from 7 to 15 m (Wisshak et al . 2005).…”