Morphometrics of the Paleocene coccolith genera Cruciplacolithus, Chiasmolithus, and Sullivania

A complex evolutionary history

Timothy Bralower, Matthew Parrow

Research output: Contribution to journalReview article

10 Citations (Scopus)

Abstract

Investigation of the evolution of calcareous nannoplankton is hindered by the extremely small size (5-10 μm) of their fossils. We introduce new technology, a scanning electron microscope connected to an image analysis system (SEM-IAS), which allows this field to be explored as never before. This system enables a host of morphocharacters to be measured and included in studies of phylogeny and evolutionary dynamics. We have applied the SEM-IAS to study the evolution of Paleocene coccolith genera Cruciplacolithus, Chiasmolithus, and Sullivania. A variety of detailed measurements have been made on over 4000 coccoliths from Deep Sea Drilling Project Site 384 in the temperate North Atlantic and Ocean Drilling Program Site 690 in the Weddell Sea off Antarctica. Our results indicate no simple relationships between morphocharacters, the shapes of all three genera are both complex and highly variable. Although most morphocharacters possess little phylogenetic significance, the areas of different shield cycles show gradual divergence between Chiasmolithus and Sullivania through the Paleocene. Change of most other morphocharacters occurs at variable rates and reversals in trends are common. Minimal correlation exists between the trends and oscillatory shape changes observed at the two sites. We conclude that these trends and oscillations represent local, transitory ecophenotypic variation of the complex form. There is little stasis in the ten-million-year record studied.

Original languageEnglish (US)
Pages (from-to)352-385
Number of pages34
JournalPaleobiology
Volume22
Issue number3
DOIs
StatePublished - Jan 1 1996

Fingerprint

coccolith
drilling
scanning electron microscopes
Oceans and Seas
Paleocene
History
image analysis
Atlantic Ocean
Electrons
history
phylogeny
Phylogeny
Antarctica
oscillation
electron
fossils
nanoplankton
oceans
Deep Sea Drilling Project
Technology

All Science Journal Classification (ASJC) codes

  • Ecology, Evolution, Behavior and Systematics
  • Ecology
  • Agricultural and Biological Sciences(all)
  • Palaeontology

Cite this

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abstract = "Investigation of the evolution of calcareous nannoplankton is hindered by the extremely small size (5-10 μm) of their fossils. We introduce new technology, a scanning electron microscope connected to an image analysis system (SEM-IAS), which allows this field to be explored as never before. This system enables a host of morphocharacters to be measured and included in studies of phylogeny and evolutionary dynamics. We have applied the SEM-IAS to study the evolution of Paleocene coccolith genera Cruciplacolithus, Chiasmolithus, and Sullivania. A variety of detailed measurements have been made on over 4000 coccoliths from Deep Sea Drilling Project Site 384 in the temperate North Atlantic and Ocean Drilling Program Site 690 in the Weddell Sea off Antarctica. Our results indicate no simple relationships between morphocharacters, the shapes of all three genera are both complex and highly variable. Although most morphocharacters possess little phylogenetic significance, the areas of different shield cycles show gradual divergence between Chiasmolithus and Sullivania through the Paleocene. Change of most other morphocharacters occurs at variable rates and reversals in trends are common. Minimal correlation exists between the trends and oscillatory shape changes observed at the two sites. We conclude that these trends and oscillations represent local, transitory ecophenotypic variation of the complex form. There is little stasis in the ten-million-year record studied.",
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Morphometrics of the Paleocene coccolith genera Cruciplacolithus, Chiasmolithus, and Sullivania : A complex evolutionary history. / Bralower, Timothy; Parrow, Matthew.

In: Paleobiology, Vol. 22, No. 3, 01.01.1996, p. 352-385.

Research output: Contribution to journalReview article

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