Revision of thelodonts, acanthodians, conodonts, and the depositional environments in the Burgen outlier (Ludlow, Silurian) of Gotland, Sweden

This is a Preprint and has not been peer reviewed. The published version of this Preprint is available: https://doi.org/10.1080/11035897.2021.1907441. This is version 1 of this Preprint.

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Authors

Emilia Jarochowska, Oskar Bremer, Alexandra Yiu, Tiiu Märss, Henning Blom, Thomas Mörs, Vivi Vajda

Abstract

Ludfordian strata exposed in the Burgen outlier in eastern Gotland record a time of initial faunal recovery after a global environmental perturbation manifested in the Ludfordian Carbon Isotope Excursion (LCIE). Vertebrate microfossils in the collection of the late Lennart Jeppsson, hosted at the Swedish Museum of Natural History, hold the key to reconstruct the dynamics of faunal immigration and diversification during the decline of the LCIE, but the stratigraphic relationships of the strata have been debated. Historically, they had been placed in the Burgsvik Formation, which included the Burgsvik Sandstone and the Burgsvik Oolite members. We revise the fauna in the Jeppsson collection and characterize key outcrops of Burgen and Kapellet. The former Burgsvik Oolite Member is here revised as the Burgen Oolite Formation. In the Burgen outlier, back-shoal facies of this formation are represented and their position in the Ozarkodina snajdri Biozone is supported. The shallow-marine position compared to the coeval strata in southern Gotland is reflected in the higher δ13Ccarb values, reaching +9.2‰. The back-shoal succession includes high-diversity metazoan reefs, which indicate a complete recovery of the carbonate producers as the LCIE declined. The impoverishment of conodonts associated with the LCIE in southern Gotland might be a product of facies preferences, as the diverse environments in the outlier yielded all 21 species known from the formation. Fish diversity also returned to normal levels as the LCIE declined, with a minimum of nine species. In line with previous reports, thelodont scales appear to dominate samples from the Burgen outlier.

DOI

https://doi.org/10.31223/X56W4R

Subjects

Biodiversity, Earth Sciences, Ecology and Evolutionary Biology, Life Sciences, Physical Sciences and Mathematics

Keywords

extinction, biostratigraphy, palynology, recovery, acanthodians, Burgsvik Formation, Ludlow, thelodonts, Lau event, carbon isotope excursion

Dates

Published: 2021-04-20 05:17

License

CC BY Attribution 4.0 International

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Conflict of interest statement:
None

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