Reading through the descriptions of each time period, it suddenly struck me that I had no idea Earth had so many mass extinctions. It's a bit mind-blowing that

Reading through the descriptions of each time period, it suddenly struck me that I had no idea Earth had so many mass extinctions. It's a bit mind-blowing that the one that put an end to the dinosaurs was not even the worst (by percentage of species killed off). I also somehow hadn't appreciated that multi-cellular animals existed before multi-cellular plants.