1. Fisheries Division, Cefas; Lowestoft NR33 0HT U.K.
2. Department of Earth Sciences Natural History Museum; London SW7 5BD U.K.
3. Laboratory of Molluscs Borissiak Paleontological Institute; Russian Academy of Sciences; Moscow 117997 Russia
4. Laboratory of Stratigraphy of Oil and Gas Bearing Reservoirs Kazan Federal University; Kazan 420000 Russia
5. Department of Stratigraphy Geological Institute; Russian Academy of Sciences; Moscow 119017 Russia