Abstract This paper summarizes research on Ordovician to Lochkovian vegetation development in a palaeogeographic framework. A terrestrialization model is described. Palaeogeographic maps are modified to explain the vegetation migrations. Land plants first evolved on the Gondwana plate and colonized Avalonia and later Laurentia and Baltica when those plates were in close proximity (Ashgill–Llandovery). South America was colonized during the Llandovery following the collapse of the ice sheet centred on the southern pole which had previously been an impassable barrier for miospores. An Aeronian–Telychian event related to the global early Silurian transgression modified the vegetation by destroying biotopes where the earliest vegetation was thriving. During the regression, trilete spore-producing plants appear to have been more able to respond to environmental changes and dominated the vegetation from the Homerian. Cryptospore-producing plants could survive under a wide range of climates, which helped them to survive during the Hirnantian glaciation. On the contrary, the earliest trilete spore-producing plants were probably climatically restricted, as suggested by latitudinal variation in assemblage composition. By the end of the Silurian, there were several phytogeographic units. Information on the earliest vegetation favours palaeogeographic reconstructions where plates are in close proximity.

Abstract Alluvial floodplains were a critical setting during the Late Devonian for the evolution of terrestriality among plants, invertebrate and vertebrates. The Red Hill site in Pennsylvania, US, provides a range of information about the physical and biotic setting of a floodplain ecosystem along the southern margin of the Euramerican landmass during the late Famennian age. An avulsion model for floodplain sedimentation is favoured in which a variety of inter-channel depositional settings formed a wide range of aquatic and terrestrial habitats. The Red Hill flora demonstrates ecological partitioning of the floodplain landscape at a high taxonomic level. In addition to progymnosperm forests, lycopsid wetlands and zygopterid fern glades, the flora includes patches of early spermatophytes occupying sites disturbed by fires. The Red Hill fauna illustrates the development of a diverse penecontemporaneous community including terrestrial invertebrates and a wide range of vertebrates that were living within aquatic habitats. Among the vertebrates are several limbed tetrapodomorphs that inhabited the burgeoning shallow water habitats on the floodplain.

Abstract A Late Cretaceous (Campanian) leaf megaflora from the Vomb Trough in southern Skåne, Sweden, has been investigated on the basis of collections held at the Swedish Museum of Natural History. The main plant-bearing locality is Köpinge, but single specimens originate from Högestad, Ingelstorp, Rödmölla, Svenstorps mölla and Tosterup. The fossil flora is dominated by the angiosperm (eudicot) Debeya ( Dewalquea ) haldemiana (Debey ex de Saporta & Marion) Halamski. Other dicots are cf. Dryophyllum sp., Ettingshausenia sp., Rarytkinia ? sp., Dicotylophyllum friesii (Nilsson) comb. nov. and Salicites wahlbergii (Nilsson) Hisinger. Conifers are represented by cf. Aachenia sp. (cone scales), Pagiophyllum sp. and Cyparissidium sp. (leaves). Single poorly preserved specimens of ferns and monocots have also been identified. The terrestrial palynomorphs (the focus herein) clearly link to the megaflora, although with different relative abundances. The fern spore Cyathidites dominates along with the conifer pollen Perinopollenites elatoides and Classopollis . Angiosperm pollen comprise up to 15% of the assemblage, represented by monocolpate, tricolpate and periporate pollen and the extinct Normapolles group. The spores in the kerogen residue show a thermal alteration index (TAI) of 2+. The flora probably represents mainly a coastal lowland Debeya /conifer forest, and is similar to approximately coeval assemblages from analogous palaeo-communities described from eastern Poland, western Ukraine and Westphalia.