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Central American Land Bridge

Central American Land Bridge

(p.164) Five Central American Land Bridge
Land Bridges
Alan Graham
University of Chicago Press

A principal focus of current discussion is when connection was fully established between northern South America and southern Central America. The consensus has been ca. 3.5 Ma ago allowing for the Great American Biotic Interchange and supported by a wealth of independent geomorphological, ocean chemistry, oceanographic (paleocurrents), and paleontological data. A recent suggestion is that zircon crystals found in ca. 13 Ma year old river deposits in Colombia came from Panama requiring land for the river to flow over (hence, continuity by that time). The crystals are now thought to have come from Colombia and the time of completion has shifted back to 3.5 Ma. Another need for greater refinement and precision when evoking ‘the land bridge’ to explain radiation and patterns of affinities is recognition that early-on the landscape was low-lying and probably supported widespread marsh and brackish-water wetlands. Better drained uplands suitable for drier-habitat and more temperate organisms appeared later at ca. 2.8-2.5 Ma. The collective evidence suggests people began having a noticeable impact on the natural vegetation along the Central American Land Bridge (sensu lato) by ca. 6000 years B.P.

Keywords:   definition, vegetation, dispersal vectors, climates, completion, zircon, people, utilization

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