New late barremian-early aptian ammonites of Dzirula massif (Georgia).
2019
Seven new species of ammonites, representatives of the extinct Cephalopod mollusks, are described. Four of them (Colchidites delicatus sp. nov., C. subangulatus sp. nov., Paraimerites nelliae sp. nov. and P. aff. katsharavai Rouch.) belong to the Barremian family Heteroceratidae Spath, but the rest – to the Early Aptian family Deshayesitidae Stoyanow (Deshayesites tamarae sp. nov.) and Aptian-Albian family Douvilleiceratidae Parona et Bonarelli (Cheloniceras accommodatum sp. nov., Ch. quadrarium modicum subsp. nov.). Distribution of the terminal group of Colchidites – Colchidites securiformis Djan. within the Late Barremian epicontinental sea of the Dzirula massif has been proved. In addition, based on study of the new palaeontological materials the assumption of the phylogenic connection between the Douvilleiceratidae Parona et Bonarelli (Cheloniceras Hyatt) and Acanthohoplitidae Stoyanow (Gargasiceras Casey, Colombiceras Hyatt) seems more convincing. The study of the abovementioned groups and families is of great significance for the relative dating of the oil-bearing rocks, detailed subdivision and correlation of sediments, as well as for reconstruction of physical and geographical properties in Early Cretaceous. Fig. 3, Tab. 7, Ref. 14.
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