Abstract
The earliest known calcified opercula are described in cryptocystidean anascan cheilostome bryozoans: Onychocella inelegans (Lonsdale, 1850) from the Lower-Upper boundary beds of the Campanian of the western Kopet Dag Range and O. spinata Favorskaja, 1980 from the Maastrichtian of the central Kyzyl Kum Desert. It is supposed that these opercula consisted of two layers: a calcified rigid basal plate (modified cryptocyst) and membranous cover (continuation of the frontal membrane). In addition, opercular scars on the perforated closure plates are described for the first time in Tamanicella panagiensis Viskova et Koromyslova, 2012 from the Late Miocene (Tortonian, Lower Maeotian) of the Taman Peninsula. It is obvious that the opercula of T. panagiensis consisted of a single membranous layer with chitinized free edges.
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