Revision and biostratigraphic implications of Thore Halle’s Permian plant fossils from the Falkland (Malvinas) Islands

Abstract

The Permian fossil plant assemblages from the Lafonia Group on the Falkland (Malvinas) Islands collected by Thore Gustav Halle on the 1907–1909 Swedish Expedition to Patagonia and Tierra del Fuego are re-described and their systematic placement revised. Two species of sphenophytes based on foliage and one on axial remains are recognized. Eight morphotypes of Glossopteris are differentiated using more rigorously defined criteria than Halle’s original character sets. A single species each of cordaitaleans and conifers are recognized. The absence of ferns and lycophytes may indicate significant taphonomic filters on the composition of the plant assemblages. Re-assessment of the characters of the fossil woods and their nomenclatural and taxonomic problems suggests that only a single species is recognizable in the assemblage. Several of the wood and leaf species bear evidence of fungal degradation along with a broad array of arthropod herbivory and oviposition damage that add to the diversity of biotic interactions documented in the middle–high southern latitude Glossopterid Biome of the late Paleozoic. The ages of the various fossiliferous units on the Falkland (Malvinas) Islands remain equivocal, but similarities with chronostratigraphically constrained leaf assemblages from the Karoo Basin, South Africa, suggest that the Bay of Harbours Formation (uppermost unit of the Lafonia Group) is referable to the upper Guadalupian to lowermost Lopingian.