The Cretaceous-Tertiary extinction witnessed the disappearance of many organismal groups, but the planktonic Foraminifera (a floating one-celled animal group) survived as a single lineage of dwarfed species. These surviving species diversified in the world's oceans and are common microfossils in marine sediments. Drs. Gerta Keller and Norman MacLeod propose a study of the surviving lineages preserved immediately following the extinction. Quantitative study of their morphology will allow reconstruction of ancestor-descendant relationships. Analysis of species diversity patterns, as well as carbon and oxygen isotope ratios preserved in shell material, will provide new insight into the environmental changes that may have coincided with or caused the extinction and subsequent evolutionary radiation. The proposed study will find a wide audience among all paleontologists interested in extinctions, among paleoecologists and paleoceanographers, and among evolutionary biologists in general.
