How were the tropical Americas formed? This volume draws on extensive, multidisciplinary research in its attempt to develop new views of the geological formation of the isthmus linking North and South America, and of the major environmental changes that reshaped the Neotropics to create its present-day marine and terrestrial ecosystems. The 24 contributors use current work in paleontology, geology, oceanography, anthropology, ecology and evolution to form this argument of rapid environmental and evolutionary change. Their conclusions seek a revision of existing interpretations of the fossil record and the processes - including invading Eurasian peoples - that have produced it.