Floristic migration in South America during the Carboniferous: phytogeographic and biostratigraphic implications

Abstract

New data on the Carboniferous flora of northern South America are combined with existing data for Gondwanaland to re-examine the floristic evolution of South America during the Carboniferous. The integration of paleobotanical, palynological, paleomagnetic, paleogeographic and paleoclimatologic data, makes it possible to reconstruct the floristic evolution of South America during the Carboniferous as a dynamic process, that was mainly controlled by the northward movement of the South American plate towards the equator during the Carboniferous. Three Carboniferous floras, the ‘cold’ Archaeosigillaria– Lepidodendropsis– Frenguellia Flora, the temperate Nothorhacopteris Flora and the tropical Euramerican Flora characterize South America. Intra-South American floristic migration is documented by the different age and composition of the Nothorhacopteris Flora. It is of late Early Carboniferous age in northern South America (Bolivia, northeastern Brazil and Peru) whereas it is of Late Carboniferous age in southern South America (Argentina and southern Brazil). The flora was adapted to warm temperate climatic conditions indicating that southern South America moved into this climatic zone during the Late Carboniferous. This migration explains the different ages recorded for the same taxa (e.g., Nothorhacopteris) in northern and southern South America. Taxonomic differences between the northern and southern Nothorhacopteris Flora reflect Viséan–Westphalian evolution.