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Abstract
Nummulites paucispira and Nummulites kaitbeyi are newly erected from the Upper Building Stone Member (Bartonian) of the Mokattam Formation at Kait Bey, Gebel Mokattam, Greater Cairo, Egypt both belong to Nummulites partschi group. N. paucispira and N. kaitbeyi are different in their ontogenetic growth stages; N. paucispira has a step of coiling from tight to lax, contrary to N. kaitbeyi. The regression line of both species indicates that both are distinct and they belong to different lineages. Detailed investigations of the new species N. paucispira n. sp. and N. kaitbeyi n. sp. of N. partschi group and their ontogenetic growth stages are discussed. This study is of considerable importance for distinguishing paleoecological events of Bartonian stage and for tracing the phylogenetic trends for the entire Tethys basin.
Acknowledgements
The authors thank Professor Amin Strougo, Ain Shams University for his help in the field work and collecting the samples and Dr. Flora Hayrapetyan, Institute of Geological Sciences, National Academy of Sciences of Armenia, for reviewing the manuscript.