Extinct Ground Sloths (Paramylodon harlani, Nothrotheriops shastensis, and Megalonyx jeffersoni)
Last Updated: Jun 14, 2017
Image credit: © San Diego Zoo Global. All rights reserved.
Order: Pilosa (anteaters and sloths)
Family: Mylodontidae (family is extinct)
Species: Paramylodon harlani
Family: Nothrotheriidae (family is extinct)
Species: Nothrotheriops shastensis
Family: Megalonychidae (family has extinct and living/extant members)
Genus: Megalonyx (extinct)
Species: Megalonyx jeffersoni
Paramylodon harlani: varied estimates from 1,000 kg (2,205 lb) to 1,089 kg (2,400 lb)
Nothrotheriops shastensis: estimated 250 kg (551 lb)
Megalonyx jeffersoni: estimated near 1,000 kg (2,205 lb)
Paramylodon harlani: 3 m (9.8 ft)
Nothrotheriops shastensis: about the size of a black bear
Megalonyx jeffersoni: 3 m (9.8 ft)
Long hairs, especially on flanks and rear limbs.
|Distribution & Status||Behavior & Ecology|
Paramylodon harlani: widely distributed across the U.S., especially in western states
Nothrotheriops shastensis: primarily western U.S. but also in Florida, Texas, Mexico
Megalonyx jeffersoni: wide distribution in over 150 sites in United States, including Alaska, northwestern Canada, Mexico
Paramylodon harlani: preferred areas of open grass or parkland, perhaps near water; not found in dry areas
Nothrotheriops shastensis: areas that were drier during the Pleistocene—open savanna scrub land with trees; deciduous forests
Megalonyx jeffersoni: gallery forests along rivers or lakes
All giant ground sloths are extinct. Causes unknown.
Studies suggest a range of movements, including tree-climbing, swimming, and burrowing.
Extinct ground sloths shared habitats with other large herbivores. Ex. Paramylodon harlani often found with mammoths in North America
Diets of ground sloths varied. Some exclusively herbivorous, some species also ate meat. See Diet & Feeding for details.
Ground sloths juveniles would have been vulnerable to the large cat predators (Smilodon, Homotherium, Panthera atrox) and perhaps Dire Wolves.
|Reproduction & Development||Species Highlights|
May have provided extended parental care. Had few young.
- The diversity of sloths in the fossil record is high; over 100 genera are recognized
- 90% of sloth genera became extinct at the end of the Pleistocene
- The adaptations and biology of living tree sloths are very different from extinct ground sloths; comparisions should be limited
- Large powerful claws on the sloths' hands were probably for digging as well as defense.
- Some ground sloths used caves as habitat
- Sloths in the mylodontid family had small bony deposits (osteoderms) imbedded in their skin; other animals that have more developed osteoderms include lizards, crocodiles, and pangolins
© 2009 San Diego Zoo Global
How to cite: Extinct Ground Sloths (Paramylodon harlani, Nothrotheriops shastensis, and Megalonyx jeffersoni) Fact Sheet, 2009. c2009. San Diego (CA): San Diego Zoo Global; [accessed YYYY Mmm dd]. http://ielc.libguides.com/sdzg/factsheets/extinctgroundsloths
(note: replace YYYY Mmm dd with date accessed, e.g., 2015 Sep 10)
Disclaimer: Although San Diego Zoo Global makes every attempt to provide accurate information, some of the facts provided may become outdated or replaced by new research findings. Questions and comments may be addressed to firstname.lastname@example.org.