Carboniferous Rain Forest Collapse
The Carboniferous rain forest collapse was one of the largest plant extinctions in history. When much of the plant life relied on a warm climate, it took just one powerful event to destroy massive amounts of rain forest. Many of these dead plants make up coal swamps, which are major sources for fossil fuels today. Some say that because of the decline of rain forests and animals that relied on them, reptiles arose to prominence.
Theories
Temperature Change- A lack of greenhouse gasses could have caused a lethal climate change. The funny thing is that these plants' success may have been their own enemy. When the forests used CO2, they themselves cooled the atmosphere and could have been responsible for their own death.
Meteorite Impact- As previously said, a meteorite impact could cause a food web collapse, starting with plant life. During the time of this extinction event, there were several major meteorite impacts that could be to blame for this catastrophe.