BIOSTRATIGRAPHY AND NEW FORMS OF LOWER PALEOZOIC FOSSILS OF THE BOGAMBIR RIDGE (<i>North Nuratau Range, South Tien Shan</i>)
Annotatsiya
The paper deals with a debatable stratigraphic position (from Proterozoic to Silurian) of the deposits making up the Bogambir Ridge of the North Nuratau Range (South Tien Shan), where new forms of chambered sponges Tadassia Zhuravleva et Pjanovskaja gen. nov. are found along with other organic remains. The Bogambir, Ortosai, and Koibulak formations are described as part of these deposits; they are of Early-Silurian (Wenlockian), Early-Cambrian(?), and Middle- or Late-Cambrian age, respectively. To confirm the last age, the Tadassia sponges appeared to be very important; they are described in this paper too. In having stauractin spicular and siliceous porous skeletons, Tadassia is similar to representatives of the order Innaecoelida Boiko, 1990, widespread in the Mesozoic, but quite drastically it differs from the Paleozoic Silicosphinctozoa with massive skeleton.