In the geological blink of an eye, mammals moved from an obscure group of vertebrates into a class of planetary dominance. This provocative study identifies the fall of dinosaurs as the factor that allowed mammals to evolve into the dominant tetrapod form.
The author refutes the widely accepted single-cause impact theory for dinosaur extinction and demonstrates that multiple factors - massive volcanic eruptions, loss of shallow seas, and extraterrestrial impact - likely led to their demise. While their avian relatives ultimately survived and thrived, terrestrial dinosaurs did not. Taking their place as the dominant land and sea tetrapods were mammals, whose radiation was explosive following nonavian dinosaur extinction.
Archibald argues that because of dinosaurs, Mesozoic mammals changed relatively slowly for 145 million years compared to the prodigious Cenozoic radiation that followed. Finally out from under the shadow of the giant reptiles, Cenozoic mammals evolved into the forms we recognize today in a mere ten million years after dinosaur extinction. Piecing together evidence from both molecular biology and the fossil record, he shows how science is edging closer to understanding exactly what happened during the mass extinctions near the K/T boundary and the radiation that followed.
J. David Archibald is a professor of biology and curator of mammals at San Diego State University and coeditor of The Rise of Placental Mammals: Origins and Relationships of the Major Extant Clades, also published by Johns Hopkins.
- Choice 2011