Miocene–Pleistocene planktic foraminifers from D. S. D. P. Sites 208 and 77, and phylogeny and classification of Cenozoic species
Rich assemblages of tropical and subtropical planktic foraminifers from two coarsely sampled upper-Cenozoic deep-sea sequences suggest the need for changes in taxonomic method with a corresponding reclassification which includes all Cenozoic species. This is necessitated by the observation that repr...
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| Format: | Book |
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University of Chicago
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| Online Access: | http://hdl.handle.net/1885/9006 https://openresearch-repository.anu.edu.au/bitstream/1885/9006/4/Fordham%2c_MiocenePleistocene1986a.pdf.jpg |
| Summary: | Rich assemblages of tropical and subtropical planktic foraminifers from two coarsely sampled upper-Cenozoic deep-sea sequences suggest the need for changes in taxonomic method with a corresponding reclassification which includes all Cenozoic species. This is necessitated by the observation that representative collections of assemblages from phylogenetic lineages exhibit unexpectedly high degrees of variation in test morphology both within assemblages and through sequences of assemblages, and so much more inclusive concepts of many species are required. Also, speciation events in many of these species lineages appear to have been preserved by the appearance of discontinuities in variation within sequences of assemblages. These observations combined with the extensive literature which documents stratigraphic distribution of infraspecific taxa are used to revise the phylogeny of late-Cenozoic species with regard to the branching sequence. This method of phylogeny reconstruction has been termed stratophenetic analysis by P.O. Gingerich. Because the common ancestry of most of these clades appears to lie in the early Cenozoic, the branching sequence is extended to the beginning of the Cenozoic based on the work of W.H. Blow. Two complementary suprageneric classifications of Cenozoic species are offered, each based on this cladogram. Both schemes refer to a revised set of generic and species taxa. The fossil species is defined cladistically: a lineage of populations existing from the splitting event of its immediate ancestor until splitting into its descendants or until terminal extinction. Degree of anagenesis associated with cladogenesis or occurring between cladogenetic events is ignored in species definition. This taxonomy results in 138 nominal Cenozoic species (four new), one for each internodal segment of the cladogram. The genus is defined phylogenetically but is neither cladistic nor, as normally applied, phylic. For primarily practical purposes the genus is used to combine species which form an ... |
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