Recognition of an extended record of euglenoid cysts: Implications for the end-Triassic mass extinction

Bas van de Schootbrugge*, Andreas Koutsodendris, Wilson Taylor, Fabian Weston, Charles Wellman, Paul K. Strother

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

The enigmatic non-pollen palynomorph Chomotriletes, occurs consistently within sediments associated with the end-Triassic mass-extinction. Based on a detailed palynological survey and other published records from Europe, Chomotriletes is prevalent within the uppermost Rhaetian Contorta and Triletes Beds and its equivalents elsewhere. Chomotriletes is now a senior synonym for Permian Circulisporites, Meso- to Cenozoic Pseudoschizaea, and Quaternary to Recent Concentricystes. Its widespread occurrence has significance for our understanding of the end-Triassic mass-extinction, but its biological affinity and ecological preference have remained contentious for almost a century. We undertook a TEM examination of a Holocene and a Pliocene example of Concentricystes and found their structure to be a close match to the wall of Jurassic Pseudoschizaea from Italy that has been interpreted to belong to cysts of the Euglenophyceae. Together with a nascent understanding of a deep time record of the euglenoid, Moyeria, Chomotriletes helps document a terrestrial signature of the Euglenophyceae in the fossil record. An extensive literature survey indicates that Chomotriletes is associated with wetlands and riverine floodplain soils, and that it inhabited mainly temperate to tropical latitudes and continues to do so to the present day. Its presence in ancient marine sediments therefore indicates transport via weathering and erosion. The association with wetlands is in line with the ecological preferences of species of the Euglenophyceae. The presence of euglenoid cysts in association with the end-Triassic extinction fits a scenario in which enhanced rainfall followed by strong soil erosion resulted in the release and redeposition of Chomotriletes into shallow marine settings.

Original languageEnglish
Article number105043
Number of pages12
JournalReview of Palaeobotany and Palynology
Volume322
Early online date21 Dec 2023
DOIs
Publication statusPublished - Mar 2024

Bibliographical note

Publisher Copyright:
© 2023

Funding

Funding was provided by the Natural Environment Research Council (grant NE/R001324/1 ) to CHW. Additional support was provided by the Human Frontiers Science Program (grant RGP 0066/2021 ) to T. Vandenbroucke, B. van de Schootbrugge, C. Looy, and B. Lomax. We thank Remco Bos (U. of Utrecht) for assistance with isolating specimens.

FundersFunder number
UK Natural Environment Research CouncilNE/R001324/1
Human Frontier Science ProgramRGP 0066/2021

    Keywords

    • Acritarch
    • Algal cyst
    • Euglena
    • NPP
    • Phycology
    • Reworked palynomorphs

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