There seem to be a number of really big macroevolutionary events in natural history, and Zimmer does well in explaining what happened and why with the fish-tetrapod event, the blind alleys, and people involved. I would have liked more detail in anatomy, DNA relationships, and the like, but that probably would have bored most people. The land animal-whale transition feels closer to home, but seems to be to be a side-show to the major events in evolutionary history. Zimmer writes well but it would be good to have a technical volume to go with it. Footnotes / endnotes would also be pleasant addition for the reader that wants to follow up, but they are missing.