Ground sloths are an example of a body-plan which has evolved several times in mammals; large semi-upright herbivores with formidable claws on their forelimbs. They were ancestral to modern sloths, but were very different in appearance and habits.
They usually walked on all fours, resting their weight on the knuckles of their ‘hands’ and the outer edges of their back feet. These feet were very strange, with the inner toes being rotated away from the ground so that their claws turned inwards. At the back of each foot was a bony extension, resembling an additional toe. Despite this curious anatomy and the great size of some of the sloths, it seems they were able to rear up on their hind limbs, using their thick tails as a third point of support. This allowed them to reach up into tall trees to bring buds, leaves, and fruit close enough to seize with their prehensile lips. It seems likely that they also used their claws for defense and competition with each other for mates.
Their metabolisms appear to have been fairly slow, a feature they share with modern sloths. Combined with their bulk and thick coats of fur offering significant insulation, they would have been able to survive on a relatively meager diet.
Megalonychids
Megalonyx (‘Great Claw’) remains were first discovered in West Virginia and named by Thomas Jefferson, who published a paper on them. Jefferson assumed that the claws must have come from a giant predator, only later learning of the existence of Megatherium and concluding that the two creatures must be related. It was a fairly typical ground sloth, distinguished mostly by the fact it lived in the pine woods of North America. Its ancestor Pliometanastes was only slightly smaller and crossed into North America before it had fully joined to South America by island-hopping. Their South-American relative, Ahytherium was only about two-thirds their weight.
Megalonyx
ST 25; DX 9; IQ 2; HT 12.
HP 25; Will 10; Per 10; FP 12; Speed 4.00; Dodge 7; Move 4.
SM +2 (3 hexes), 2,000 lbs.
Claw (11): 2d+3 cutting.
Traits: Bad Sight (Low Resolution); Discriminatory Smell; DR 3; Night Vision 1; Reduced Consumption 2 (Food Only); Semi-Upright; Temperature Tolerance (Cold) 3; Wild Animal.
Skills: Brawling-11; Survival (Woodlands)-10.
Use the same profile for Pliometanastes. For Ahytherium (1,300 lbs.) reduce ST and HP to 22 (claw damage 2d+1).
Megatherids
Megatherium was one of the largest ground sloths, around the size of an Asian elephant. It had an even more robust skeleton and proportionally longer claws that its relatives. Its relative Eremotherium was even larger and lived in warmer regions, so it may have had little or no fur.
Megatherium
ST 41; DX 8; IQ 2; HT 13.
HP 41; Will 10; Per 10; FP 13; Speed 4.00; Dodge 7; Move 5.
SM +3 (10 hexes), 8,500 lbs.
Claw (10): 4d+5 cutting or impaling.
Traits: Bad Sight (Low Resolution); Discriminatory Smell; DR 4; Night Vision 1; Reduced Consumption 2 (Food Only); Semi-Upright; Temperature Tolerance (Cold) 2; Wild Animal.
Skills: Brawling-10; Survival (Woodlands)-10.
For Eremotherium (10,000 lbs.) increase ST and HP to 43 (claw damage 5d+3) and remove Temperature Tolerance.
Mylodontids
Some members of this family had numerous small bony plates embedded in their skin, making them very challenging prey even for fearsome predators such as Smilodon populator. Mylodon lived in the Southern end of South America and was around the size of a modern rhinoceros. Although it mostly ate grasses, there is evidence that it also enjoyed meat from time to time, probably scavenged carrion or the remains of unfortunate predators which misjudged the sloth. Its close relative Paramylodon lived in North America, and was very similar. Lestodon lived slightly further North of Mylodon and grew to the size of an elephant. Glossotherium was smaller, and avoided predators and inclement weather by digging immense burrows. Catonyx was a distant relative which grew to about the same size as Mylodon, while Scelidotherium and Thinobadistes were only about half its weight.
Mylodon
ST 31; DX 9; IQ 2; HT 12.
HP 31; Will 10; Per 10; FP 12; Speed 4.00; Dodge 7; Move 4.
SM +3 (8 hexes), 3,600 lbs.
Claw (11): 3d+6 crushing.
Traits: Bad Sight (Low Resolution); Discriminatory Smell; DR 5; Night Vision 1; Reduced Consumption 2 (Food Only); Semi-Upright; Temperature Tolerance (Cold) 2; Wild Animal.
Skills: Brawling-11; Survival (Plains)-10.
Use the same profile for Paramylodon. For Lestodon (9,000 lbs.) increase ST and HP to 42 (claw damage 4d+9), and DR to 6. For Glossotherium (2,800 lbs.), reduce ST and HP to 28 (claw damage 3d+4), SM to +2, DR to 4. For Catonyx, reduce DR to 3 and Temperature Tolerance to 1. For Scelidotherium (1,900 lbs) or Thinobadistes (2,000 lbs.) reduce ST and HP to 25 (claw damage 2d+5), SM to +1, DR to 2, and Temperature Tolerance to 1.
Nothrotherids
Although not as impressive as the truly giant sloths, these bear-size animals still had thick hide and fearsome claws. Nothrotherium lived in dry, open forests and may have been able to climb trees, while Nothrotheriops was slightly larger and lived in arid scrubland.
Nothrotherium
ST 14; DX 10; IQ 2; HT 12.
HP 14; Will 10; Per 10; FP 12; Speed 4.00; Dodge 7; Move 4.
SM +1 (3 hexes), 330 lbs.
Claw (12): 1d cutting.
Traits: Bad Sight (Low Resolution); Discriminatory Smell; DR 2; Night Vision 1; Reduced Consumption 2; Semi-Upright; Wild Animal.
Skills: Brawling-12; Climbing-12; Survival (Woodlands)-10.
For Nothrotheriops (550 lbs.) increase ST and HP to 16, remove Climbing skill and replace Survival (Woodlands) with Survival (Desert)-13.