Paleoecological inferences about the Late Quaternary giant ground sloths from the Americas

Abstract

The Occlusal Surface Area index together with the body mass contribute to better understanding the paleoecology and evolution of the giant sloths in the Americas. The giant sloths from southern South America probably had higher levels of fermentation/lower metabolic requirements, whereas the tropical taxa had higher metabolic requirements. The sloths that dispersed into Central and North America were most likely derived from tropical taxa based on the patterns observed in this study. Relative Muzzle Width and the Hypsodonty indices were used to infer the dietary adaptation of several late Pleistocene/early Holocene giant ground sloths from the Americas. The Nothrotheriidae and Megatheridae taxa were adapted to a browser or mixed-feeder “browser” diet, the Mylodontidae taxa to a variety of dietary types, and the Megalonychidae taxa to a mixed-feeder browser diet. However, these dietary adaptations do not necessarily reflect food niches. In general, Megalonychidae and Nothrotheriidae were climber species, Mylodontidae taxa were digger species, and Megatheriidae taxa were fully terrestrial species.