Journal article
A spike in malformed chitinozoans announces the Ireviken Ocean Anoxic event in the lower Wenlock
Global and planetary change, Vol.258, 105302
03/2026
DOI: 10.1016/j.gloplacha.2026.105302
Abstract
The Silurian record is punctuated by several large, positive stable carbon isotope excursions that coincide with extinction events. Increasingly, these events are interpreted as Silurian Ocean Anoxic Events (OAEs). Malformed chitinozoans (extinct organic-walled zooplankton) recently emerged as potential early indicators of these biogeochemical disturbances. This study is part of an integrated research effort testing the hypothesis that increased chitinozoan teratology is a hallmark signature of most of these Silurian OAEs. Here we focus on the Ireviken Event (lower Wenlock; 433 Ma).
Examination of more than 500,000 chitinozoan specimens in 74 samples from the well-studied Lusklint 1 outcrop and the complementary Lusklint-1 core (Gotland, Sweden), allowed their classification into normal, abnormal, and potentially abnormal categories. Ratios of normal versus abnormal chitinozoans across the Ireviken Event reveal malformation concentrations 3 to 33 times higher than background levels. Notably, the rise in teratological forms begins below the lowest conodont extinction datums that traditionally define the onset of the extinction event. This extended anomaly suggests that environmental stress, likely related to marine redox instability and metal contamination, preceded the earliest biotic turnover.
In vivo teratologic growth is an emerging powerful proxy for identifying original paleo-oceanographic stress. Our findings establish malformed chitinozoans as early harbingers of this pivotal Silurian OAE. By integrating detailed records of teratology with the stratigraphic context of the Ireviken OAE, this study demonstrates that malformations offer a sensitive and underutilized tool for reconstructing the sequence and drivers of Silurian OAEs.
•Elevated numbers of malformed chitinozoans mark the Ireviken Event•The eight types of teratology far exceed intraspecific morphological variation•We confirm chitinozoan teratology as a hallmark signature of Silurian OAEs•Chitinozoans are early responders to the environmental changes of the Ireviken Event
Details
- Title: Subtitle
- A spike in malformed chitinozoans announces the Ireviken Ocean Anoxic event in the lower Wenlock
- Creators
- Iris Vancoppenolle - University College GhentPoul Emsbo - United States Geological SurveyPatrick I. McLaughlinTim De Backer - Ghent UniversityCarolina Klock - Ghent UniversityMikael Calner - Lund UniversityBradley D. Cramer - University of IowaAxel Munnecke - Friedrich-Alexander-Universität Erlangen-NürnbergThijs R.A. Vandenbroucke - Ghent University
- Resource Type
- Journal article
- Publication Details
- Global and planetary change, Vol.258, 105302
- DOI
- 10.1016/j.gloplacha.2026.105302
- ISSN
- 0921-8181
- eISSN
- 1872-6364
- Publisher
- Elsevier B.V
- Grant note
- Research Foundation, Flanders (FWO): G038722N HFSP- Human Frontiers Science Program: RGP0066/2021 Bijzonder Onderzoeksfonds-Universiteit Gent (BOF- UGent) starting grant: BOF17/STA/013 Crafoord Foundation (Lund): 20220567 FWO: I013118N
IV, PE, PIM, TDB and TRAV are funded by the Research Foundation, Flanders (FWO) through research grant G038722N, (Monsters of the Apocalypse) . CK and TRAV received support from the HFSP- Human Frontiers Science Program (grant RGP0066/2021) . TDB was funded through a Bijzonder Onderzoeksfonds-Universiteit Gent (BOF- UGent) starting grant (BOF17/STA/013 to TRAV) . The authors acknowledge Crafoord Foundation (Lund) grant 20220567 to MC for recovery of the Lusklint-1 core. Chitinozoan SEM images were generated using infrastructure funded through FWO grant I013118N. We thank Emilia Jarochowska and Monica Streifert for assistance with the field collections, Georg Maier for preparing and measuring the stable isotope samples, and Sabine Vancauwenberghe for help with the lab processing of the samples. Anthony Butcher and Sonia Camina provided helpful reviews. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
- Language
- English
- Electronic publication date
- 01/12/2026
- Date published
- 03/2026
- Academic Unit
- International Programs; School of Earth, Environment, and Sustainability
- Record Identifier
- 9985121500902771
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