First record of scyphocrinoids in Türkiye and recognition of the Silurian/Devonian boundary interval (Halevikdere Section, Eastern Taurides)

During the Silurian/Devonian (S/D) boundary interval, scyphocrinoids (Crinoidea, Echinodermata) flourished on a global scale. The first record of scyphocrinoids from Türkiye, especially represented by their bulbuous loboliths, is now described from the Halevikdere Section in the Eastern Taurides. The Devonian part of the section is more than 1300 m thick and covers a time span from the S/D boundary interval to the Late Devonian (Famennian). It consists mainly of fine-grained to sandy siliciclastics, event-driven conglomerates/fanglomerates and biogenic carbonates deposited in deep shelf to shallow-water coastal settings. The S/D boundary interval was measured and studied in great detail. The dominant lithology in the boundary interval is dark organic-rich shales with a few intercalated limestones, commonly as separate nodules. For biostratigraphic age determination palynomorphs and ostracods are most important and allow narrowing down the S/D boundary to an interval of a few metres. The scyphocrinoid loboliths are of the plated type and mainly derived from two layers adjacent to the S/D boundary. They are assigned to the camarocrinoids, in particular to the genus Camarocrinus (with the species Camarocrinus legrandi). The function of the loboliths as floating buoys is briefly discussed and supported.