ABSTRACT
BACKGROUND: PANGEA AND THE END-PERMIAN EXTINCTION In the last two chapters, we saw how the terrestrial environment became green with plant life, closely followed by animals rustling through the undergrowth; by the Pennsylvanian Period lush tropical forests were widespread. These forests were dominated by lycopod trees and pteridosperm (seed-ferns) understorey, and animal life included amphibians, insects, and arachnids. The Paleozoic seas had witnessed the rise of arthropods (e.g. trilobites, eurypterids), planktonic graptolites, and brachiopods, and coral reefs were widespread in tropical regions. However, the end of both the Permian Period and the Paleozoic Era was defined by the sudden change in fauna and flora which resulted from a major mass extinction event – the greatest the Earth has ever witnessed, wiping out 95% of all life. As we now enter the Triassic Period, and the Mesozoic Era, life on Earth is quite different from what it was before. Trilobites, eurypterids, and graptolites are extinct; bivalved mollusks, not brachiopods, are now the dominant shelled animals on the sea floor; there are new types of corals forming reefs; reptiles have diversified greatly and increased in size, and gymnospermous trees, especially conifers, now dominate the flora on land.
