And another 60 million (the Carboniferous period) to figure out how to break down lignin. Trees were the equivalent of our plastic pollution crises - no way to return the nutrients to the ecosystem or even deal with the mass other than burial or burning - for millions of years.

All fungi today that rot wood descend from just one fungal evolution event, and even today we don't really understand how they manage to digest the lignin. https://www.scientificamerican.com/article/mushroom-evolution-breaks-down-lignin-slows-coal-formation/