Rotaliid Shell Architecture and the Palaeodiversity of the Lockhartia Sea

Abstract

In the Paleogene the earliest foraminiferal diversity hotspot seems to center in Southern Turkey, in an area of considerable extension around the Lake Van. The centers of Paleogene larger foraminiferal diversity is defined as the Lockhartia communities. This group of complex and large-sized K-strategist rotaliids may serve as index fossil for a so-called Lockhartia Sea, a part of the Paleogene Neotethys, reaching in Asia from Tibet to Pakistan, Afghanistan, Iran and southern Turkey, in Africa from Somalia to Egypt and all over the Arabian Peninsula. The basic structural elements of most rotaliid foraminifera differentiate more than six subfamilies each represented by a single genus that is more than a single phylogenetic lineage. There are three main types of architecture defining the subfamilies Rotaliinae, Lockhartiinae and Kathininae closely evolving together. Counting the taxa per Shallow Benthic Zones reveals common trends in distribution: a rapid increase of taxa in the Paleocene and stability on a very low level from the Cuisian to the beginning of the Bartonian. For the rotaliids, the peak of diversity is observed in SBZ 4, in the Miscellaneidae one zone earlier, in SBZ 3.