Bornmalm, L. Fossils and Strata, Scandinavian University Press, Oslo, Norway, No. 41, 96pp., 1997. ISBN 82-00-37666-4. USD 29.00.
This monograph describes the benthic foraminifera (>125 µm) from two Deep Sea Drilling Project (DSDP) Sites in the Caribbean Sea (Site 502) and the eastern equatorial Pacific Ocean (Site 503) from the terminal Miocene (5.5 Ma) to the basal Pleistocene (1.7 Ma). The objectives of the study were as follows: (1) to analyse changes in absolute abundance and diversity of deep-sea benthic foraminifera; (2) to analyse fluctuations in the coarse fraction of the sediment (>63 µm), calcite dissolution based on the degree of fragmentation of planktonic foraminifera, flux of organic matter to the sea floor based on accumulation rates of benthic foraminifera; and (3) to analyse the taxonomy and illustrate the benthic foraminifera using scanning electron microscopy. The study focuses on the palaeoceanographic implications of the closure of the Isthmus of Panama in the middle Pliocene (3.5-3.0 Ma).
The monograph opens with an abstract which is followed by a comprehensive contents page. The monograph is divided into four main sections: introduction, results, palaeoceanographic interpretations and taxonomic description of selected species. The introduction provides background to the research, present day oceanographic setting of the area and the material and methods used. The results are presented under the following headings: coarse-fraction analysis, fragmentation patterns, benthic foraminifer accumulation rates (BFAR), calcium carbonate content, stable isotopes, diversity of the benthic foraminifer faunas, faunal composition, faunal differences between the holes and Q-mode principal components analysis. The text is interspersed with many graphs which show comparisons of the data from the two Sites. The raw data are shown in a number of large tables interspersed with the main text. In my opinion, it would have been better to have put these data in appendices at the end of the monograph, as are the counts of benthic foraminifera, particularly since some of them take up whole pages. The results section presents a lot of new and important data. I do feel, however, that there are not enough graphs showing abundance fluctuations of the commonly occurring benthic foraminiferal taxa. Reliance has been placed on statistical methods, particularly Q-mode principal components analysis, but only changes in absolute abundances of three common taxa (Nuttallides umbonifera, Cibicidoides wuellerstorfi and Oridorsalis umbonatus) are shown as graphs. I realise that absolute abundances of benthic foraminifera were one of the main focuses of attention, but, in my opinion it would have been important, and interesting, to have shown something on relative abundance (%) fluctuations of selected taxa as a comparison.
The next section deals with the palaeoceanographic interpretations of the results with particular reference to the closure of the Isthmus of Panama. Some interesting points emerge but the discussion is not very well focused.
The remainder and bulk (~60%) of the monograph, is devoted to the taxonomy of selected benthic foraminiferal taxa from the study area, most of which have a cosmopolitan distribution. The classification scheme used chiefly follows Loeblich and Tappan (1964, 1987). Over 130 species are discussed and most are illustrated by scanning electron micrographs (15 plates) which are interspersed in the text. Each species includes a synonymy list, a brief description, in most cases remarks on their taxonomic position and in some cases, if available, some very useful information concerning their ecology based on the literature. Sadly, there are no detailed discussions of how the species of particular genera can be distinguished from one another. The taxonomy section is followed by a list of references but no conclusions of the research are given.
Overall, this publication presents some useful and interesting information. Although it is aimed more at the specialist, it would be of interest to both micropalaeontologists and palaeoceanographers.
Chris W. Smart, Department of Geological Sciences, University of Plymouth, Drake Circus, Plymouth, Devon PL4 8AA.
References:
Loeblich, A. R. and Tappan, H. 1964. Protista 2. Sarcodina chiefly ‘Thecamoebians’ and Foraminiferida. In: Moore, R. C. (ed.) Treatise on invertebrate paleontology, Part C, 2 vols. Geological Society of America and University of Kansas Press, Boulder, Colorado and Lawrence, Kansas.
Loeblich, A. R. and Tappan, H. 1987. Foraminiferal genera and their classification. Van Nostrand Reinhold Company, New York.