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Isotope data from amino acids indicate Darwin's ground sloth was not an herbivore.

Published version
Peer-reviewed

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Authors

Tejada, Julia V 
Flynn, John J 
MacPhee, Ross 
O'Connell, Tamsin C 
Cerling, Thure E 

Abstract

Fossil sloths are regarded as obligate herbivores for reasons including peculiarities of their craniodental morphology and that all living sloths feed exclusively on plants. We challenge this view based on isotopic analyses of nitrogen of specific amino acids, which show that Darwin's ground sloth Mylodon darwinii was an opportunistic omnivore. This direct evidence of omnivory in an ancient sloth requires reevaluation of the ecological structure of South American Cenozoic mammalian communities, as sloths represented a major component of these ecosystems across the past 34 Myr. Furthermore, by analyzing modern mammals with known diets, we provide a basis for reliable interpretation of nitrogen isotopes of amino acids of fossils. We argue that a widely used equation to determine trophic position is unnecessary, and that the relative isotopic values of the amino acids glutamate and phenylalanine alone permit reliable reconstructions of trophic positions of extant and extinct mammals.

Description

Keywords

Amino Acids, Animals, DNA, Mitochondrial, Ecosystem, Feeding Behavior, Fossils, Herbivory, Isotopes, Mammals, Nitrogen Isotopes, Phylogeny, Sloths, Xenarthra

Journal Title

Sci Rep

Conference Name

Journal ISSN

2045-2322
2045-2322

Volume Title

11

Publisher

Springer Science and Business Media LLC