Calcareous tube-dwelling encrusting polychaetes from a lower-middle Miocene sedimentary succession, Cairo-Suez District, Egypt

This work represents the first systematic study of fossil calcareous tube-dwelling encrusting polychaetes to be conducted in Egypt. A total of 396 polychaete specimens were reported from the lower and middle Miocene Gharra and Geniefa fonnations, respectively, exposed at the Gebel Ghana section, Cairo-Suez District, Egypt. The tubeworms have been found attached to shells of oysters followed by pectinid shells, but there are few other gastropods and corals having rare attached tubes. At least nine polychaete taxa, belonging to eight genera, have been identified and systematically described. The tubewonn association is dominated by Hydtvides (39.9% of the total polychaete specimens), Filograna (25.8%), Spirobranchus (12.6%), Hyalopomatus (10.6%), and Glomerula (8.1%). Stratigraphically, Hydroides sp. and spirorbid worms were exclusively reported from the lower Miocene succession; Protula? sp. from the middle Miocene, whereas the remaining species (Filograna cf. implexa, Hyalopomatus? sp., Hydroides cf. elegans, Protis? sp., Spirobranchus cf. triqueter and Glomerula? sp.) were reported from lower-middle Miocene sediments. Only fully marine polychaete species occur in the association, characterizing shallow subtropical marine conditions. The species reported show palaeobiogeographical affinities with the Miocene of Italy, Austria, and Slovakia and are characteristic of present-day Atlantic-Mediterranean regions.

Automated summary

This study is the first systematic investigation of fossil calcareous tube-dwelling polychaetes in Egypt. Nine polychaete taxa belonging to eight genera were identified from the lower and middle Miocene formations. The dominant tube-dwelling polychaete genera include Hydtvides, Filograna, Spirobranchus, Hyalopomatus, and Glomerula. The identified species have paleobiogeographical affinities with Miocene species in Italy, Austria, and Slovakia.