An early Devonian flora from the Baviaanskloof Formation (Table Mountain Group) of South Africa

Robert W Gess,Cyrille Prestianni

doi:10.1038/s41598-021-90180-z

Abstract

Newly discovered early plant bearing lenses from the Baviaanskloof Formation at Impofu Dam in the Eastern Cape Province of South Africa provide evidence for one of the most diverse Late Silurian to Early Devonian assemblages known to date. This work represents the first account of this flora. Fifteen taxa are presented, including eleven diagnosed to existing genera, of which eight may be reasonably diagnosed to existing species including several species of the genus Cooksonia. Three new taxa, Krommia parvapila, Elandia itshoba and Mtshaelo kougaensis are described. This flora is furthermore remarkable for the large number of complete or sub-complete specimens allowing good understanding of earliest plant architecture. The assemblage bears the greatest resemblance to Early Lochkovian assemblages from the Parana Basin of Brazil and the Anglo Welsh basin. Biostratigraphic constraints on the dating of the Baviaanskloof Formation are provided by this flora, which represents the oldest known from Africa.

Highlights

The late Silurian to earliest Devonian comprised a pivotal time in the evolution of early terrestrial ecosystems characterized by the progressive decline of cryptophytes and the rise of several lineages of trilete spore producing plants
The upper of these lenses (UPL) includes a greater proportion of larger plants which are frequently more fragmentary
This paper represents a first account of the newly discovered early land plant bearing lenses from the Baviaanskloof Formation strata at Impofu Dam in the Eastern Cape province of South Africa

Summary

Introduction

The late Silurian to earliest Devonian comprised a pivotal time in the evolution of early terrestrial ecosystems characterized by the progressive decline of cryptophytes (sensu1) and the rise of several lineages of trilete spore producing plants. The only previously published high latitude floras from this time interval are those from the Paraná Basin of Brasil and Argentina 2–6, with a single plant species having been reported from southern Africa This latter taxon, Dutoitia pulchra, was originally reported as being of Silurian age and as being from Bokkeveld Group strata exposed in the Blaaukrantz River valley in South Africa. Comparison of the new flora with coeval assemblages from the Paraná (Brazil) and Anglo-Welsh Basins (United Kingdom) sheds new light on the formerly uncertain dating of the Baviaanskloof Formation, and by extension the age of the Dutoitia type material, as well as the transition from the Table Mountain Group to the overlying Bokkeveld Group. Prior to designation of the Baviaanskloof Formation[30,58] these strata were often considered to form the basal part of the Bokkeveld Group[16,70]

Methods

Findings

Discussion

Conclusion