| mhorn | Дата: Thursday, 22.07.2010, 19:56 | Сообщение # 1 |
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| Lominadze T., Topchishvili M., Tsereteli I., Todria V. (2010) The relationship between the Jurassic marine fauna of Gerorgia and changes in geological environment // Georgian National Museum. Proceedings of the Natural and Prehistoric Section. No.2. P.82-89. [in Russian with English summary]
pdf: http://rogov.zwz.ru/Lominadze%20%20et%20al,2010_J_amm_environm.pdf
The issue of the quantitative dependence of the Jurassic marine fauna of Georgia on changes in the geological conditions has been examined. In the Early Jurassic the quantity of ammonites genera changed insignificantly at different times but did not exceed the number of seventeen, regardless the enlargement of the sea basin and the intensification of transgression. In the Middle Jurassic-Bajocian the number of genera increased to twenty three and in Callovian, with the beginning of a new, strong transgression it reached the maximum of twenty nine. The picture considering the development of corals is quite different. In the Middle Jurassic only separate, single forms were found. Corals reached astounding growth only in the Middle-Late Oxfordian. As for the microfauna its maximum genera number is observed also in the Middle Oxfordian. It was that time span when coral reefs and lagoons beyond reefs were formed creating unfavourable conditions for development and distribution of ammonites.
Middle Jurassic - Lower Cretaceous ammonites & aptychi
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