Diatom life cycles and ecology in the Cretaceous. Issue 3 (13th March 2017)

• Record Type: Journal Article
• Authors: Jewson, David H.; Harwood, David M.
• Editors: Kroth, P.
• Is Part Of: Journal of phycology. Volume 53:Issue 3(2017:Jun.)
• Page Start: 616
• Page End: 628
• Publication Date: 2017-03-13
• Subjects: cell cycle -- cretaceous -- diatom -- ecology -- evolution -- life cycle -- marine -- size; Algae -- Periodicals; 579.8
• DOI: 10.1111/jpy.12519
• Languages: English
• ISSNs: 0022-3646

Abstract

Abstract : 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.