Atosa procyonids murids crossingover crossingover

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Unformatted text preview: ungulates Extinct Ground Sloths Toxodon N.A. to S.A. Procyonids Murids Crossing Over Crossing Over 3 Million Years Ago Middle Pliocene Just before final emergence of the isthmus Last corridors for dispersal of marine organisms between Caribbean Sea & Pacific Ocean Late Pliocene Land Bridge Complete Mammalian Exchange Reaches Climax Effects of Interchange Effects of Interchange Exchange uniform at first, becoming unbalanced later S.A. fauna made little impact in N.A. N.A. fauna radiated explosively in S.A. Reasons for imbalance: N.A. fauna longer subjected to repeated immigrations Better competitors & predators Webb & Rancy three­phase model Three­phase Model Three­phase Model Webb & Rancy (1996) First Phase Late Pliocene Just after land bridge formed Glacial conditions shrunk forests Allowed Savanna habitats to dominate tropical latitudes Establishing a corridor for savanna adapted animals Three­phase Model Three­phase Model Webb & Rancy (199...
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This note was uploaded on 10/02/2011 for the course BIOL 1407 taught by Professor Lisagloyna during the Spring '09 term at Austin Community College.

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