Diatom life cycles and ecology in the Cretaceous

The earliest known diatom fossils with well‐preserved siliceous frustules are from Lower Cretaceous neritic marine deposits in Antarctica. In this study, we analyzed the cell wall structure to establish whether their cell and life cycles were similar to modern forms. At least two filamentous species...

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Bibliographic Details
Published in:Journal of phycology 2017-06, Vol.53 (3), p.616-628
Main Authors: Jewson, David H., Harwood, David M., Kroth, P.
Format: Article
Language:English
Subjects:
Adaptation
Biological Evolution
cell cycle
Cell division
Cell size
Cell Wall - ultrastructure
Cell walls
Cretaceous
Cycles
Deposits
diatom
Diatoms
Diatoms - physiology
Diatoms - ultrastructure
Ecological adaptation
Ecology
Evolution
Fossils
Fossils - ultrastructure
Height
life cycle
Life cycles
Life History Traits
Mantle
marine
Microscopy, Electron, Scanning
Restoration
Sex
size
Species Specificity
Structures
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Summary:The earliest known diatom fossils with well‐preserved siliceous frustules are from Lower Cretaceous neritic marine deposits in Antarctica. In this study, we analyzed the cell wall structure to establish whether their cell and life cycles were similar to modern forms. At least two filamentous species (Basilicostephanus ornatus and Archepyrgus melosiroides) had girdle band structures that functioned during cell division in a similar way to present day Aulacoseira species. Also, size analyses of cell diameter indicated that the cyclic process of size decline and size restoration used to time modern diatom life cycles was present in five species from the Lower Cretaceous (B. ornatus, A. melosiroides, Gladius antiquus, Ancylopyrgus reticulatus, Kreagra forfex) as well as two species from Upper Cretaceous deposits (Trinacria anissimowii and Eunotogramma fueloepi) from the Southwest Pacific. The results indicate that the “Diatom Sex Clock” was present from an early evolutionary stage. Other ecological adaptations included changes in mantle height and coiling. Overall, the results suggest that at least some of the species in these early assemblages are on a direct ancestral line to modern forms.
ISSN:0022-3646
1529-8817
DOI:10.1111/jpy.12519