• 1. Whales are Mammals
• 2. Relation to Hippos
• 3. Ambulocetus
• 4. Whales become aquatic
• 5. Cladogram

The Evolution of Whales: 6. Further Reading

• Evolution of Seals, Sea Lions and Walruses (only links)
• The Evolution of Dugongs and Manatees (only links)
• up to Life

Elsewhere on the web

• Wikipedia: Evolution of cetaceans
• Cetacean Paleaobiology from University of Bristol
• The evolution of whales from Berkeley's Understanding Evolution site
• Research on the Origin and Early Evolution of Whales (Cetacea) from Philip Gingerich's pages at the University of Michigan
• Whale Origins from Northeastern Ohio Universities
• Whale Evolution on Squidoo
• Hitchhiker's Guide to the Galaxy on Whale Evolution
• The Origin of Whales and the Power of Independent Evidence from TalkOrigins.org
• Whence Whales by Kate Wong (Scientific American article, 2001)
• Evolution of Whales by Babinski, adapted from Nat Geo (CPU drain)

Books

• At the Water's Edge: Fish with Fingers, Whales with Legs, and How Life Came Ashore but Then Went Back to Sea by Carl Zimmer (1998)
• Evolution: What the Fossils Say and Why It Matters by Donald R. Prothero (2007)
• Aquagenesis: The Origin and Evolution of Life in the Sea by Richard Ellis (2001)
• Why Evolution is True by Jerry Coyne (2009)
• Written in Stone by Brian Switek (2010)
• The Emergence of Whales: Evolutionary Patterns in the Origin of Cetacea by J.G.M. Thewissen (1998)
• The Encyclopedia of Marine Mammals edited by W.F. Perrin, Bernd G. Würsig and J.G.M. Thewissen (2002)

Articles

• Evolutionary Treasures Locked in the Teeth of Early Whales by Brian Switek in his Laelaps blog in October 2011
• The Mammals That Conquered the Seas by Kate Wong in the May 2002 Scientific American (requires a digital subsciption; article also available in the 2006 book "Evolution: A Scientific American Reader").

Research papers

• Relationships of Cetacea (Artiodactyla) Among Mammals: Increased Taxon Sampling Alters Interpretations of Key Fossils and Character Evolution