Gondwana was covered by dwarf lycophytes, even smaller than those of the Angaran realm. Subtropical and temperate lycophytes such as Lepidodendropsis, Archaeosigillaria, and Frenguellia could be found in some parts of the supercontinent, such as Argentina and Australia. In the middle Tournaisian glaciation, species-poor frigid tundra developed in western Argentina. These south polar tundras hosted the oldest known seed plants in Gondwanan territories, which likely spread south across a land bridge once the Rheic Ocean closed between Laurussia and Gondwana. Tournaisian terrestrial sediments in South America are additionally characterized by the miospore index fossil Waltzispora lanzonii. The floral diversity of Tournaisian southern tundra consists almost entirely of relict Devonian genera; this suggests that Late Devonian land plant extinctions in lower latitudes were mostly driven by competition from new tropical species, rather than global environmental pressures. Notable formations Albert Formation (New Brunswick, Canada) Agua de Lucho Formation (Argentina) Ballagan Formation / Cementstone Group (Scotland) Herbesskaya Formation (Russia) Horton Bluff Formation (Nova Scotia, Canada) Mansfield Group (Australia) Price Formation (West Virginia / Virginia, United States) Tournai Formation (Belgium) References Bibliography ; 1832: Mémoire sur la constitution géologique de la province de Liège, Mémoires couronnés par l'Académie Royale des Sciences et Belles-Lettres de Bruxelles 8 (3), VII. ; 2004: A Geologic Time Scale 2004, Cambridge University Press ; 2006: The Carboniferous system, use of the new official names for the subsystems, series and stages, Geologica Acta 4(3), pp 403–407 ; 2006: Global time scale and regional stratigraphic reference scales of Central and West Europe, East Europe, Tethys, South China, and North America as used in the Devonian–Carboniferous–Permian Correlation Chart 2003 (DCP 2003), Palaeogeography, Palaeoclimatology, Palaeoecology 240 (1-2): pp 318–372 ; 1937: Die Devon-Karbon-Grenze, Comptes Rendus (2) du Cinquième Congrès International de Stratigraphie et Géologie du Carbonifère, Heerlen 1935 (2), pp 703–714 ; 1991: Decision on the Devonian–Carboniferous Boundary Stratotype, Episodes 14 (4), pp 331–336 External links Early Carboniferous timescale at the website of the Norwegian network of offshore records of geology and stratigraphy Tournaisian, Geowhen Database The Tournaisian age, www.palaeos.com Mississippian geochronology Geological ages . Stratigraphy of Europe Tournai