While it has been suggested that the giant sloth may have been partly carnivorous, this is a controversial claim. Richard Fariña and Ernesto Blanco of the Universidad de la República in Montevideo have analysed a fossil skeleton of "M. americanum" and discovered that its olecranon—the part of the elbow to which the triceps muscle attaches—was very short. This adaptation is found in carnivores and optimises speed rather than strength. The researchers say this would have enabled "M. americanum" to use its claws like daggers. They suggest that to add nutrients to its diet, "Megatherium" may have taken over the kills of "Smilodon". Based on the estimated strength and mechanical advantage of its biceps, it has been proposed that "Megatherium" could have overturned adult glyptodonts (large, armored xenarthrans, related to armadillos) as a means of scavenging or hunting these animals. However, noting that sloths lack the carnassials typical of predators and that traces of bone are absent from the many preserved deposits of sloth dung, Paul Martin has described this proposal as "fanciful". Carbon isotope analysis has found that "Megatherium" has isotope values similar to other megafaunal herbivores such as mammoths, glyptodonts, and "Macrauchenia", and significantly unlike omnivorous and carnivorous mammals, suggesting that "Megatherium" was an obligate herbivore.