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Terebella lapilloides Munster, 1833 from the Upper Jurassic-Lower Cretaceous Inalti carbonates, northern Turkey: its taxonomic position and paleoenvironmental-paleoecological significance

2014-01-01
Kaya, Mustafa Yucel
Altıner, Demir
The agglutinating annelid Terebella lapilloides Munster, 1833 is commonly encountered in reefal deposits from the Late Jurassic. This annelid is described and documented for the first time from the Upper Jurassic-Lower Cretaceous carbonates of the Inalti Formation in the Central Pontides, Turkey. The whole Inalti formation, 395 m in thickness, was studied near Burnuk village and 105 samples were collected along the section. The investigated thin sections reveal the shallow water and the reefal/fore-reefal character of the carbonates with coral-sponge frame-builders. The bioconstituents are accompanied by various microencrusters and microproblematica (such as Lithocodium aggregatum, Bacinella-type structures, Koskinobullina socialis, Radiomura cautica, Perturbatacrusta leini, Thaumatoporella parvovesiculifera, and encrusting sponges and bryozoans), boring bivalves, annelids (serpulids and terebellids), echinoids, rare benthic foraminifera, and abundant Crescentiella morronensis. Rare occurrences of calpionellids - particularly in the upper levels of the section - are also observed. The morphological analysis clearly indicates that the Terebella lapilloides population belongs to the agglutinated annelids, which are classified under the phylum Annelida, class Polychaete, and order Terebellida. Terebella lapilloides is a typical marker of fore-reef to upper slope or toe of slope breccia facies and is generally found in low-energy settings with dysoxic conditions. In some levels of the studied section, Terebella and Crescentiella form an in situ association; however, Terebella never cooccurs with other microencrusters.