To avoid these problems, data from each worker has been examined in this study as an independent data set. The estimates of evolutionary change (metrics) resulting from the analyses are compared to each other in intervals of overlap to check for consistency, and combined to create a composite record of evolutionary change over the entire Neogene.

Radiolarian stratigraphic occurrence data from each author, if available from more than one site, were combined to make composite range charts of taxa occurrences (Appendix 1 and Appendix 2). Data sources included the author's own files and ODP's online archives (NGDC's ODP archive and the ODP archive). All samples were dated using age models developed by the Neptune project (Lazarus 1994) and the Neptune Database at the MRC research center in Basel  and are based on the published leg primary stratigraphic data sets (Barron et al. 1991; Harwood et al. 1992) and the Berggren et al. (1995) time scale. First and last occurrences of taxa were estimated for the most part using per taxon average stratigraphic gap size, which, in the absence of detailed information on preservation potential variation (Marshall 1990, 1994, 1997), appears to be a reasonable measure of potential age uncertainty for each event in sections with non-uniform discrete sampling.

The data was binned into 1 m.y. intervals for summary statistics. This binning interval was chosen as the maximum resolution that was compatible with the average age uncertainty in the placement of first and last occurrence events. With the 1 m.y. interval chosen, the event age uncertainty estimates largely fell within the bin intervals. Where they crossed a bin boundary the mid-point of the uncertainty interval was used. Diversity was estimated by range-through methods, and evolutionary change was represented by the metrics percent first occurrences, percent last occurrences and turnover (sum of the two former). Individual taxon longevities (with or without the inclusion of taxa whose ranges are truncated by the upper and lower limits of the sample sets) were also compiled for selected time intervals and higher taxonomic groups.

Paleoenvironmental data were compiled from several of the same sites used for radiolarian analysis, and samples ages were obtained using the identical age models for the sites. Stable isotopes of oxygen and carbon are from Leg 120 sites 747 and 751 (Mackensen et al. 1992; Wright and Miller 1992), while percent carbonate in the bulk sediment is from Site 751 (Mackensen et al. 1992). Neogene stable oxygen isotope data from these sites estimate both Southern Ocean near-surface water temperatures and ice sheet volume on Antarctica, while stable carbon isotope ratio data record both local and global changes in patterns of organic carbon storage, and thus indirectly indicate changes in ocean nutrient chemistry (Kennett 1982, Miller and Fairbanks 1985; Mackensen et al. 1992; Wright and Miller 1992). In the Antarctic Neogene, pelagic sediments such as those studied here consist of essentially only two major components - biogenic carbonate and biogenic opal (mostly diatoms). Although dissolution also affects the record, within the sites reported here changes in carbonate content primarily reflect changes in oceanic productivity - both absolute values and the nature of the dominant primary producers (Kennett and Barker 1990; Mackensen et al. 1992; Diester-Haass 1994; Diester-Haass and Zahn 1996; Diester-Haass et al. 2002).