Extinct Ground Sloths (Paramylodon harlani, Nothrotheriops shastensis, and Megalonyx jeffersoni) Fact Sheet: Diet & Feeding

Clues to fossil mammals' diets come from teeth, skull shape and the positions and strength of major jaw muscles, from fossilized dung and guts, from oxygen isotopes in bone and teeth, and from diets of similar modern animals.

• There are no modern analogues for ground sloths. (France et al 2007)
• Ground sloths traditionally seen as non-ruminant herbivores with hindgut fermentation, subsisting on a wide variety of plants. (France et al 2007)
• A great deal is known about some species of fossil sloths' diets from deposits of dung found in caves in the southwestern U.S. (Poinar et al 1998)
  • Plant pollen in Shasta ground sloth (Nothrotheriops) dung from Rampart Cave, Arizona studied by Hansen (1978) contained 72 genera of plants; favored plants were Desert Globe Mallows (Sphaeralcea ambigua) and Mormon Tea (Ephedra nevadensis)
  • Dung from Gypsum Cave, Nevada of Shasta ground sloth analyzed for plant DNA revealed six families and two orders of plants, with plants in the caper family and the lilly family (probably yucca and agave) being common. (Poinar 1998)
• Harlan's Ground Sloth (Paramylodon harlani) variously interpreted as a grazer, a browser, or a mixed feeder but looking at dentin isotopes Ruez ( 2005) said it was a mixed feeder with grass being one or the main component of the diet.
• From tooth studies (Bargo 2001), anatomical studies of elbows (Fariña & Blanco 1996) conclude Megatherium from South America may have been omnivouous, consuming meat by either hunting or scavenging; other researchers have suggested diets with animal protein for other sloth species. (France et al 2007)
• France et al (2007) looked at carbon and nitrogen isotopes in sloth bone collagen and concluded that a Megalonyx from Virginia was primarily a herbivore, but that it might have have consumed a small amount of meat.
• Other researchers examined isotopes from sloths at Rancho La Brea and said Paramylodon harlani looks like a strict herbivore. (Coltrain et al 2004)
• Paramylodonand other mylodon sloths postulated to have dug with its powerful claws and arms for roots and tubers (Bargo et al 2006)
  • This digging behavior in search of food added grit to the diet which may have been one factor influencing evolution of their extremely high crowned teeth.

Bargo et al. (2006)
Coltrain et al. (2004)
Fariña and Blanco (1996)
France et al. (2007)
Hansen (1978)
Martin (1975)
Poinar et al. (1998)
Ruez (2005)