I love to hear learned people say, "I don't know," when asked something like, "Did the leaves of the tree ferns in Pennsylvanian times turn bright red and yellow in the fall?" And I love to hear them then speculate on all the ways one might look at such a question, reasoning from modern relatives, from known climate, from carotene. And I love to think of the fern forests and populate them with the whirr of huge dragonflies, that must have had very large creatures to catch on the wing to make it worthwhile being huge. Think of that. Populate those forests. Reason with the honest scientists, who fill those ancient places with the brilliant spores of conjecture, with songs, rain, and the swish of falling fronds.