"At the Water's Edge: Fish with Fingers, Whales with Legs"
by Carl Zimmer
Link: http://www.amazon.co.uk/At-Waters-Edge-Fingers-Legs/dp/0684856239/
Reading history and reviews
Finished in 2007
I really enjoyed this one, another popular science book but this time about the process of "macroevolution", which is essentially large-scale changes such as "how did aquatic animals evolve to survive on land?" (the fish with fingers) and "how did land-based animals evolve to survive in water?" (the whales with legs). Highly recommended.