Jefferson’s Ground Sloth
Megalonyx jeffersonii
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Chordata
Mammalia
Pilosa
Megatherioidea
Megalonychidae
Megalonyx jeffersonii
Named by Thomas Jefferson, Megalonyx jeffersonii was a massive ground sloth that once roamed woodlands across North America. Though slow-moving, its size and strength made it formidable — yet it likely fell victim to early human hunters during the Pleistocene megafaunal extinction.
Description
Megalonyx jeffersonii, commonly known as Jefferson's Ground Sloth, was a large, heavily built herbivore native to North America during the Pleistocene epoch. Measuring about 3 meters in length and weighing up to 1,000 kilograms, it possessed a robust frame similar in size to a modern ox. Its hind limbs were plantigrade (flat-footed), and along with a stout tail, allowed it to rear up into a semi-erect position to feed on tree leaves. The hands featured three large claws, likely used for grasping and defense. The teeth of Megalonyx jeffersonii were high-crowned, suitable for its herbivorous diet.
Quick Facts
Max Mass
Shoulder Height
Standing Height
Length
Diet
Trophic Level
1100
1.5
2.25
3
kg
m
m
m
Mixed Feeder
Omnivores – Balanced
Hunt History
Though direct evidence is sparse, Megalonyx likely faced pressure from Paleoindian hunters in North America. Its slow gait, predictable foraging routes, and large size may have made it vulnerable to ambush tactics. Butchery marks found on bones in certain locations suggest humans at least scavenged — if not actively hunted — these large sloths.
Archaeological Evidence of Human Predation:
Sheridan Cave (Ohio, USA) – ~11,000 years ago: Butchered Megalonyx bones found with stone tools, strongly suggesting human processing.
Kimmswick Site (Missouri, USA) – ~12,000 years ago: Megalonyx remains found alongside mastodons and Clovis-style projectile points.
Yukon River Basin (Alaska) – ~11,000 years ago: Possible Megalonyx remains found in human occupation layers, with signs of cutting.
Time & Range
Extinction Status
Globally Extinct
Extinction Date
Temporal Range
Region
11000
BP
Late Pleistocene
North America
Wiki Link
Fat Analysis
Fatness Profile:
Medium
Fat %
5
Est. Renderable Fat
55
kg
Targeted Organs
Visceral & subcutaneous
Adipose Depots
Visceral/subcutaneous (general)
Preferred Cuts
Visceral depot
Hunt Difficulty (x/5)
4