Research Article

Phanerozoic Trends in the Global Diversity of Marine Invertebrates

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Science  04 Jul 2008:
Vol. 321, Issue 5885, pp. 97-100
DOI: 10.1126/science.1156963

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  1. Fig. 1.

    Genus-level diversity of both extant and extinct marine invertebrates (metazoans less tetrapods) during the Phanerozoic, based on a sampling-standardized analysis of the Paleobiology Database. Points represent 48 temporal bins defined to be of roughly equal length (averaging 11 My) by grouping short geological stages when necessary. Vertical lines show the 95% confidence intervals based on Chernoff bounds, which are always conservative regardless of the number of genera that could be sampled or variation in their sampling probabilities (18). Data are standardized by repeatedly drawing collections from a randomly generated set of 65 publications until a quota of 16,200 specimens has been recovered in each bin. On average, 461 collections had to be drawn to reach this total. The curve shows average values found across 20 separate subsampling trials—enough to yield high precision with such large sample sizes. Ma, million years ago. Cm, Cambrian; O, Ordovician; S, Silurian; D, Devonian; C, Carboniferous; P, Permian; Tr, Triassic; J, Jurassic; K, Cretaceous; Pg, Paleogene; Ng, Neogene.

  2. Fig. 2.

    Evenness estimates (thick line) for 11-My-long bins, based on Hurlbert's PIE index (27). The values are computed from the calibrated occurrence weights used in subsampling, and each is a weighted moving averages across five consecutive bins. Changes in global diversity (thin line, same as in Fig. 1) are shown for comparison.

  3. Fig. 3.

    Low- (30°S to 30°N paleolatitude) and high-latitude subsampling curves for individual 11-My-long bins. Gray lines indicate low-latitude data. (A) Data for the Cenozoic bins, including the Early/Middle Miocene (dotted lines) and Late Miocene/Pliocene/Pleistocene (solid lines). Black lines indicate data from above 30°N. (B) Data for the Ordovician bins, including the Llanvirn (dotted lines) and Caradoc (solid lines). Black lines denote data from below 30°S.

  4. Fig. 4.

    Genus-level diversity curves based on Sepkoski's compendium [thin line (5)] and our new data (thick line). Counts are of marine metazoan genera crossing boundaries between temporal bins (boundary crossers) and exclude tetrapods. Ranges are pulled forward from first fossil appearances to the Recent, instead of ending at the last known fossil appearance. Extant genera are systematically marked as such based on Sepkoski's compendium and the primary literature. There is no correction for sampling, and genera are assumed to be sampled everywhere within their ranges because Sepkoski's traditional synoptic data (5) do not record occurrences within individual collections.