The Mesozoic Split: Biogeographical and Evolutionary Consequences of the South America Africa Continental Separation on Vertebrate Fauna

Abstract

Richard Murdoch Montgomery

This review examines the progressive separation of South America and Africa, which began approximately 145 million years ago during the Early Cretaceous and completed 100 million years ago. The rifting process created the South Atlantic Ocean and profoundly influenced vertebrate evolution on both continents. Initially connected as part of Gondwana, the gradual separation led to vicariant speciation and distinct evolutionary trajectories for previously continuous vertebrate populations. The separation particularly affected terrestrial vertebrates, resulting in parallel evolution of similar ecological niches on both continents, while creating opportunities for endemic lineages to develop. This process explains many modern distribution patterns and evolutionary relationships between South American and African vertebrate taxa, including parallel radiations in groups such as titanosaur dinosaurs during the Cretaceous and later parallel developments in mammals during the Cenozoic. The isolation also contributed to unique characteristics in each continent's modern vertebrate assemblages, such as the distinctive nature of South American primates and African ungulates.

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