Early-Middle Triassic recovery
Palynological data from Hungary were used to reconstruct the pattern of vegetational changes during the recovery phase (fig. 1) following the end-Permian biotic crisis. The earliest assemblages of the Hungarian record contain an overwhelming abundance of Pleuromeia spores (Densoisporites nejburgii). These are successionally replaced by pollen grains of seedferns and conifers. Some of the initially invading conifers and seedferns are shrubby or herbaceous. One well-studied plant is Aethophyllum, the only herbaceous conifer known so far. The size of fossil logs and root structures support the idea that the succesional climax vegetation includes genuine conifer trees. This gradual replacement of Pleuromeia vegetation towards a Voltzia-dominant climax vegetation can be recognized in palynological records (fig. 2) from Europe and adjacent parts of Africa and Asia. The newly arrived conifers are unknown from the extensive Late Permian megafossil and palynological record, and little is known about the source areas for these immigrants. It is likely that their ancestors survived in isolated refugia where suitable habitats continued to exist for extensive periods. The successional replacement of quillworts by conifers took place within a period of ~0.5 million years.
Looy C.V., Brugman W.A., Dilcher D.L. and Visscher H., 1999. The delayed resurgence of forests after the Permian-Triassic ecologic crisis. Proceedings National Academy of Science, USA 96: 13857-13862. PDF
Commentary: Pfefferkorn, H.M., 1999. Recuperation from mass extinctions. Proceedings National Academy of Science 101: 13597-13599. PDF