After the Dinosaurs: The Age of Mammals

Did you know that North America had its own species of zebra? Or that there was a wolf-like carnivorous mammal -- with hooves? And there once was a horned rodent whose corkscrew-shaped burrows are still visible today? If this sort of thing interests you then you will enjoy Donald Prothero's book, After the Dinosaurs: The Age of Mammals (Bloomington, IN: University of Indiana Press, 2006).

With the exception of birds, dinosaurs became extinct 65 million years ago when a giant bolide crashed into the earth just off the Yucatan peninsula. This extinction left thousands of niches open for other animals to occupy, and that is just what the mammals did. From their humble origins as nocturnal rat-like animals scurrying out of the way of the dinosuars, the mammals evolved into numerous spendid forms such as giant sloths that were the size of elephants, rhinocerus with long fur, and deer that stood seven feet tall at the shoulder and carried spectacular 100 pound antlers on their heads.

This is the story of the Cenozoic Era -- The Age of Mammals -- as earth warmed up to become a vast greenhouse in the Eocene, 55 million years ago, and then cooling rapidly so that 33 million years ago the glacial ice returned. The book is carefully organized, starting with the sweeping events at the end of the Cretaceous and a discussion of how fossil evidence is used, and then moving on to devote one chapter to reviewing each geological Epoch from the Paleocene onwards until the present day. There are plenty of pictures and diagrams in the book, but few are in color -- which is a pity.

Each chapter begins with an examination of geological data, then moves on to the climatic events of the period and continues with detailed analyses of biological evolutionary changes both for sea and land. Evolutionary developments among the mammals are discussed for each ocean and continent but since the author recognizes that no living creature develops or lives in a vacuum, he also mentions the evolution of other animals, such as birds and reptiles, as well as the dominant flora that was present.

Basically, this book is a sometimes-quirky overview of the common fauna of each continent and the environments that they lived in. It is written for a general audience so even though there is a lot of good information in this book, if you're looking for intimate details on a particular species or group, you might be disappointed. However, if you want a good scientifically sound summary of the age of mammals, this is an excellent resource.

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Donald R. Prothero is Professor of Geology at Occidental College and Lecturer in Geobiology at the California Institute of Technology. He has published 21 books, including Earth: Portrait of a Planet; The Evolution of Earth; and Horns, Tusks, and Flippers: The Evolution of Hoofed Mammals and Their Relatives. He lives in La Crescenta, California.

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