When Dinosaurs Roamed a Fiery Landscape

Fire is hardly an unexpected danger/ part of nature.. There are forest fires readily across the world even now, in a comparatively low-oxygen atmosphere. There are plenty of trees that need fire to be able to germinate, such as the giant redwood, which was dying out until rangers stopped putting out forest fires back in the last century.
Also though, it may be possible that charcoal has a higher preservation bias than most other wood remains, petrification for example only happens under very rare circumstances in swamps, for example (I think, I don't have my palaeobotany lecture notes with me atm..). More charcoal in the fossil record than other wood remains would put a slight bias on the data of anyone studying the topic