1995/08/01 by Paul N. Pearson · 2 citations
Earth and Planetary Sciences · #Geology and Paleoclimatology Research #Marine Biology and Ecology Research #Paleontology and Stratigraphy of Fossils
paper · doi:10.1080/10292389509380516
openalex publication_date 1995/08/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/29
Survivorship curves with taxon lifespans normalised to variations in the real‐time extinction rate (the ‘Corrected Survivorship Score’ technique) are plotted for various fossil groups. Of five groups tested at the ‘species level’ (strictly speaking, Linnean morphospecies), only the calcareous nannoplankton are found to have had a constant extinction probability with respect to morphospecies age. The planktonic foraminifer, trilobite, conodont and graptolite data all show a significant age‐dependent effect (convexity of survivorship curves), which reveals in each case a progressively increasing extinction probability as morphospecies became older. This effect is found to be much reduced for trilobite genera and absent for ammonoid families, suggesting that age‐dependency of extinction probability is primarily a characteristic of the species level in some, but not all groups. However, the pattern may be partly an artefact of taxonomic methodology. Morphospecies range data, which are gathered primarily for biostratigraphic purposes, are far from ideal for the purpose of survivorship analysis. Therefore, survivorship curves for a specially‐developed lineage phylogeny of Palaeogene planktonic foraminifera are also presented. These do not indicate a similar age‐dependency to the extinction probability with respect to either the terminal or non‐terminal lineages.