Carboniferous rainforest collapse instance of extinction event
The Carboniferous rainforest collapse (CRC) was a minor extinction event that occurred around 305 million years ago in the Carboniferous period. It altered the vast coal forests that covered the equatorial region of Euramerica (Europe and America). This event may have fragmented the forests into isolated refugia or ecological 'islands', which in turn encouraged dwarfism and, shortly after, extinction of many plant and animal species. Following the event, coal-forming tropical forests continued in large areas of the Earth, but their extent and composition were changed. 
The event occurred at the end of the Moscovian and continued into the early Kasimovian stages of the Pennsylvanian (Upper Carboniferous).Possible causes
Atmosphere and climate
There are several hypotheses about the nature and cause of the Carboniferous Rainforest Collapse, some of which include climate change. After a late Bashkirian interval of glaciation, high-frequency shifts in seasonality from humid to arid times began.The Carboniferous period is characterised by the formation of coal deposits which were formed within a context of the removal of atmospheric carbon. In the latest Middle Pennsylvanian (late Moscovian) a cycle of aridification began. At the time of the Carboniferous rainforest collapse, the climate became cooler and drier. This is reflected in the rock record as the Earth entered a short, intense ice age. Sea levels dropped by about 100 metres (330 ft), and glacial ice covered most of the southern continent of Gondwana. The climate was unfavourable to rainforests and much of the biodiversity in them. Rainforests shrank into isolated patches mostly confined to wet valleys further and further apart. Little of the original lycopsid rainforest biome survived this initial climate crisis. The concentration of carbon dioxide in the atmosphere crashed to one of its all time global lows in the Pennsylvanian and early Permian.Then a succeeding period of global warming reversed the climatic trend; the remaining rainforests, unable to survive the rapidly changing conditions, were finally wiped out.As the climate aridified again through the later Paleozoic, rainforests were eventually replaced by seasonally dry biomes. Though the exact speed and nature of the collapse is not clear, it is thought to have occurred relatively quickly in geologic terms, only a few thousand years at most.
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