The book has some very useful information, including a "Family Tree" with a timeline showing the relationships of the different animals profiled, with a separate tree just for the primates, including Homo sapiens. A chart showing the average global temperatures from the Cretaceous Period (140 to 65 million years ago) to the present is handy for keeping track of major climate changes that affect the earth during the programme. Each chapter features a map of the world, which shows the relative positions of the continents, positions of the shorelines in comparison to recent times, size of the polar ice caps and the dominant plant types.
Walking with Prehistoric Beasts begins 49 million years ago during the Early Eocene Epoch (55 to 36 million years ago). Fifteen million years have elapsed since the extinction of the dinosaurs. Sea levels and global temperatures are high, and the earth is covered in tropical and subtropical jungles. The angiosperms (flowering plants) are spreading. Mammals are still small; the first primates, bats, rodents, ungulates and carnivorous mammals have appeared. The animals we see in this segment can be found preserved in the Messel oil shales, near Frankfurt, Germany.
We meet a family of Leptictidium, a small, omnivorous (eating both plants and animals) mammal whose name means "delicate weasel." Leptictidium must be careful, as there are large predators lurking nearby. Gastornis, a giant carnivorous bird related to Diatryma, is hunting to feed her young chick. Ambulocetus, an early whale whose name means "walking whale," patrols both in and out of the water. Propalaeotherium, one of the earliest horses, is nervous as well, with these large predators lying in wait. Godinotia, a lemur-like primate, clambers about in the trees. The giant ant Formicium giganteum, at one inch in length shows that it isn't only the large predators that are dangerous.
