Harlan's Ground Sloth

Ground Sloth in water

NPS Photo

 
Photo of fossilized footprint of Harlan’s ground sloth with scientific scale.
Fossilized footprint of Harlan’s ground sloth.

NPS Photo

Many animals, from the very large to the odd lived during the Ice Age. Harlan’s Ground Sloth seems to be one of the most bizarre animals from that era. A mix of large and odd, these large, furry animals are related to modern sloths, armadillos, and anteaters. Unlike its smaller modern cousin, Harlan’s ground sloths could be as tall as modern elephants and as heavy as a small car.

Sheer size was not the only odd part of a Harlan’s ground sloth. These giants were bulky, with short necks, powerful chests, and massive jaws. The sloth also had three claws per hand for digging, grabbing, or defending themselves. Just like armored armadillos today, the sloth had a protective coat of rough, brown fur, with nickel-sized bone plates underneath their skin. Scientists called this the “dermal ossicles” or bone skin.

Ground sloths migrated to North America during the Ice Age. They spent their lives wondering open-grasslands with water sources, like rivers and lakes. Using its stubby snout and sense of smell, the sloth may have found and eat grasses, shrubs, and plants with flowers. The need for water sources may have brought Harlan’s Ground Sloths to White Sands during the Ice Age. Before the sand dunes existed, a giant lake called Lake Otero filled the area. It provided a water source that attracted many Ice Age animals, including Harlan’s Ground Sloths.

Today on the old dried lakebed of Lake Otero or Alkali Flat, Harlan’s Ground Sloths left clues that they were here. Many fossilized footprints are visible. They had crescent shaped footprints. Their back feet twisted inward when they walked. This made them walk slowly, almost like waddling. These large strong slow moving animals became easy targets for daring predators such as Paleo-Human hunters
The Giant ground sloth of course does not live today. Around 10,000 years ago, the large Ice Age animals died out. Scientists still debate why the larger animals disappeared. The Harlan ground sloth is reminder of a time long past.

References

Lange, Ian M. Ice Age Mammals of North America: A Guide to the Big, the Hairy, and the Bizarre. Missoula, Montana: Mountain Press Publishing Company, 2002.
Bustos et al., Sci. Adv. 2018; 4: eaar7621 25 April 2018, Footprints preserve terminal Pleistocene hunt?: Human-sloth interactions in North America

Last updated: March 8, 2019

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