Morphometric study of porosity and morphology of fossil Globigerinoides, during the Late Oligocene and Early Pliocene. Implications for the construction of a climatic and environmental paleoproxy
Globigerinoides is a group of planktonic foraminifera who appeared in the world's oceans around the Late Oligocene and are still largely present in the equatorial, tropical and subtropical regions of the modern Ocean. Several proposals of phylogeny have been presented since their discovery by d...
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| Format: | Dataset |
| Language: | English |
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PANGAEA
2018
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| Online Access: | https://doi.pangaea.de/10.1594/PANGAEA.890078 https://doi.org/10.1594/PANGAEA.890078 |
| Summary: | Globigerinoides is a group of planktonic foraminifera who appeared in the world's oceans around the Late Oligocene and are still largely present in the equatorial, tropical and subtropical regions of the modern Ocean. Several proposals of phylogeny have been presented since their discovery by d'Orbigny (1839), without reaching a consensus. Recent molecular studies have revealed an unexpectedly great and sometimes cryptic complexity, which further complicates the relationships between species of this genus. As a complementary contribution to this problem, the present study attempts a morphometric approach on fossil species from Late Oligocene and Early Pliocene. The study focuses on an analysis of (1) the porosity of the test and (2) the general morphology of fossil specimens. The porosity of the test appears to be mostly determined by the temperature of the sea-surface (SST) as related to latitude, but also by productivity. Especially in the vicinity of the equator porosity of the test is found to be an efficient indicator for paleoenvironmental conditions. The morphometric analysis of the tests reveals a single cluster of Globigerinoides morphologies during the Late Oligocene, and two separate such clusters during the Early Pliocene. The Late Oligocene cluster is suggested to reflect the range of the single species Globigerinoides primordius during an early phase of stabilization of its morphology prior to speciation into younger morpho-species. During the Early Pliocene each of the two clusters are interpreted to represent mixtures of several morphologically close species. One cluster includes species like G. ruber, G. conglobatus, G. obliquus while the other cluster is composed of G. sacculifer-like morphologies (with or without sac). However, statistical analysis of the present morphometric study was not successful for unambiguously separating specific groups within the two recognized Early Pliocene clusters. Suggestions are envisioned concerning promising experiments for characterization and distinction of ... |
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