The Tournaisian recovery of terrestrial vegetation following the end Devonian mass extinction

Reeves, Emma J (2017) The Tournaisian recovery of terrestrial vegetation following the end Devonian mass extinction. 61st Annual Meeting of the Palaeontological Association, Imperial College London, London, United Kingdom. 17 Dec 2017 - 19 Nov 2024 . pp. 56-57 .

Abstract

To understand how terrestrial vegetation was impacted by and recovered from the End Devonian Mass Extinction, a quantitative record of Tournaisian plant spores has been acquired from a 500 m borehole through the Ballagan Formation and related outcrop sections in the Scottish Borders. This is part of the NERC TW:eed project – an integrated study of the earliest Carboniferous tetrapods and their world. The immediate post-extinction vegetation was simple and then progressively increased in diversity, including inceptions and the return of some Devonian plant groups. After this initial reestablishment, the creeping lycopod Oxroadia (Anaplanisporites baccatus with its abundant megaspore Lagenicula subpilosa) became dominant, forming dense thickets on the floodplain. These thickets were repeatedly interspersed, on the tens of meters scale, by Prolycospora claytonii-dominated assemblages. Although not known in situ, a strong association with fragments of Genomosperma kidstoni indicates a seed plant affinity. Additionally, a marked increase in abundance of Spelaeotriletes crustatus in the late Tournaisian suggests an increasing abundance of progymnosperms. Quantitative abundance of selected spores correlates with palaeosol distribution, highlighting repeated climatic fluctuations between wetter and drier episodes. CONISS analysis reveals eight distinct assemblages that can be mapped onto long Milankovitch cycles, identified in marginal marine sections.

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