Land bridge

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The Isthmus of Panama is a land bridge whose appearance 3 million years ago enabled the Great American Biotic Interchange, in which animals and plants from the north colonized the south, and vice versa.[1]

In biogeography, a land bridge is an isthmus or wider land connection between otherwise separate areas, over which animals and plants are able to cross and colonize new lands. A land bridge can be created by marine regression, in which sea levels fall, exposing shallow, previously submerged sections of continental shelf; or when new land is created by plate tectonics; or occasionally when the sea floor rises due to post-glacial rebound after an ice age.

Prominent examples[edit]

Map of Sahul and Sunda, land masses that have provided land bridges at various points throughout the Pleistocene

Former land bridges[edit]

Current land bridges[edit]

Land bridge theory[edit]

In the 19th century, scientists including Joseph Dalton Hooker noted puzzling geological, botanical, and zoological similarities between widely separated areas. To solve these problems, they proposed land bridges between appropriate land masses.[2][3] In geology, the concept was first proposed by Jules Marcou in Lettres sur les roches du Jura et leur distribution géographique dans les deux hémisphères ("Letters on the rocks of the Jura [Mountains] and their geographic distribution in the two hemispheres"), 1857–1860.[3]

The hypothetical land bridges included:[3]

  • Archatlantis from the West Indies to North Africa
  • Archhelenis from Brazil to South Africa
  • Archiboreis in the North Atlantic
  • Archigalenis from Central America through Hawaii to Northeast Asia
  • Archinotis from South America to Antarctica
  • Lemuria in the Indian Ocean

The theory of continental drift provided an alternate explanation that did not require land bridges. However the continental drift theory was not widely accepted until the development of plate tectonics in the early 1960s, which more completely explained the motion of continents over geological time.

See also[edit]


  1. ^ a b Webb, S. David (23 August 2006). "The Great American Biotic Interchange: Patterns and Processes". Annals of the Missouri Botanical Garden. 93 (2): 245–257. doi:10.3417/0026-6493(2006)93[245:TGABIP]2.0.CO;2. S2CID 198152030.
  2. ^ Winkworth, Richard C. (2010). "Darwin and dispersal". Biology International. 47: 139–144.
  3. ^ a b c Corliss, William R. (June 1975). Mysteries Beneath the Sea. Apollo Editions. ISBN 978-0815203735. Chapter 5: "Up-and-Down Landbridges".

Further reading[edit]

External links[edit]