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Title: Neogene sloth assemblages ( M ammalia, P ilosa) of the C ocinetas B asin ( L a G uajira, C olombia): implications for the G reat A merican B iotic I nterchange

We describe sloth assemblages from theCocinetasBasin (LaGuajira peninsula,Colombia), found in theNeogeneCastilletes andWare formations, located in northernmostSouthAmerica, documenting otherwise poorly known biotas. The tentative referral of a specimen to a small megatherioid sloth,Hyperleptus?, from the early–middleMioceneCastilletesFormation, suggests affinities of this fauna with the distantSantaCruzFormation and documents a large latitudinal distribution for this taxon. The latePlioceneWareFormation is much more diverse, with five distinct taxa representing every family of ‘ground sloths’. This diversity is also remarkable at the ecological level, with sloths spanning over two orders of magnitude of body mass and probably having different feeding strategies. Being only a few hundred kilometres away from theIsthmus ofPanama, and a few hundred thousand years older than the classically recognized first main pulse of theGreatAmericanBiotic interchange (GABI1), theWareFormation furthermore documents an important fauna for the understanding of this major event inNeogene palaeobiogeography. The sloths for which unambiguous affinities were recovered are not closely related to the early immigrants found inNorthAmerica beforeGABI1.

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Medium: X Size: p. 563-582
["p. 563-582"]
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National Science Foundation
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