I read about When Fish Got Feet, Sharks Got Teeth, and Bugs Began to Swarm: A Cartoon Prehistory of Life Long Before Dinosaurs by Hannah Bonner in this wonderful post at I.N.K (Interesting Nonfiction for Kids). M and I had read a little about animals that existed before dinosaurs and we both wanted to learn more. We placed a hold on When Fish Got Feet at our library and checked out the companion volume, When Bugs Were Big, Plants Were Strange, and Tetrapods Stalked the Earth. Both books are written with humor sometimes sassy in tone and while many of the jokes go over M’s 4.5yo head, we enjoyed reading When Bugs Were Big together. This is an era of history I know very little about and I’m fascinated by the plants and creatures that existed during the Carboniferous period, the primary focus of this book.
For a huge list of books on fossils, dinosaurs, and prehistory, check out this page by retired science librarian, Jack Mount, which I also found via I.N.K.

[...] Writes (Nothing 5. 100 Scope Notes (Most Extreme Bugs) 6. Abby the Librarian (Albino Animals) 7. Sarah N. (When Bugs Were Big) 8. Becky’s Book Reviews (What’s Inside Your Tummy, Mommy?) 9. I.N.K. (FIFTEEN BOOK [...]