How to translate text using browser tools
1 July 2003 What is Nummulites lyelli? Evolution in large foraminifera during the Middle Eocene, Egypt
Mohamed Boukhary, Dalia Kamal
Author Affiliations +

Nummulites lyelli D'Archiac and Haime 1853, is described for the first time from photographs of both generations, using material from the species type locality at El-Mishgigah, in the El-Gharaq Formation exposed in the Fayum Depression. Nummulites praelyelli n.sp., described from the Mokattam Formation below the Citadel of Salah El Din, in the eastern part of Cairo, is interpreted to be the ancestor of Nummulites lyelli Archiac and Haime. The main ontogenetic trend in this newly identified lineage is a gradual change from tight to lax coiling during growth, whereas the opposite onotgenetic trend is found in the lineage of Nummulites gizehensis (Forskål) In this work, the group of Nummulites gizehensis and allied species is separated from the group of Nummulites lyelli, partly on this basis but definitively on the basis of granulation and septal morphology. We suggest that at the beginning of the Bartonian, Nummulites lyelli ecologically displaced the Late Lutetian Nummulites gizehensis in both space and time, rather than evolving from it.

Mohamed Boukhary and Dalia Kamal "What is Nummulites lyelli? Evolution in large foraminifera during the Middle Eocene, Egypt," Micropaleontology 49(2), 171-187, (1 July 2003).[0171:WINLEI]2.0.CO;2
Received: 10 January 2002; Accepted: 1 October 2002; Published: 1 July 2003

This article is only available to subscribers.
It is not available for individual sale.

Get copyright permission
Back to Top