The Giant Ground Sloth--An Oversized Hamster Quiz

Answer: Caribbean Islands, including Cuba

Giant ground sloths lived and died with the other megafauna at the end of the Pleistocene, either affected by climate change or the appearance of humans, but down in the Caribbean, there were several species only a little smaller that blissfully lived on for another 5,000 years or more. Parocnus lived on in Cuba, but on Hispaniola, the Caribbean island shared by Haiti and the Dominican Republic today, Neocnus lived another 500 years, until 4,500 years ago.

Answer: Thomas Jefferson

Megalonyx jeffersonii, or Jefferson's ground sloth, was named in his honor, but it wasn't just a scientist's way to try to get more funding. Jefferson himself took an interest in the fossil claw sent back to him. It was dug from the floor of a cave in the western part of Virginia, now West Virginia, when some workers were digging soil for saltpeter. Jefferson read a paper on it during a meeting of the American Philosophical Society in Philadelphia, March 10, 1797. With the long claw, the creature seemed to Jefferson like a lion or panther, but more study by experts soon ruled that out and for a while it was considered something of a mystery beast, until the giant ground sloth was better understood.

Answer: five tons, like an elephant

Megatherium of South America, one of the biggest of the sloth genuses, was about the size of an elephant, weighing over five tons. Eremotherium, a genus found in North America, was about the same size. On the other end of the scale, Nothrotheriops, which lived in Mexico and the southern US, was only about 550 pounds and was about waist high to a human, rising just above head height when it stood up to reach for tree branches. Before the sloths became giant, they were represented by their ancestor Hapalops, an older genus found in South America and about the size of a small dog, or a modern sloth.

Answer: tree leaves, some other grasses and local plants, possibly a little meat

Sloths had hip bones that allowed them to stand up to reach higher branches, strong claws to rib off bark and tear down limbs, and small blunt teeth to grind up fibrous plant tissue. Fossilized dung from a southwest American species shows it ate mesquite, cacti, agave, yucca, and Joshua trees. Paramylodon harlani, a species widespread in North America, had teeth that suggeted it grazed on grasses.

Megalonyx, a smaller genus in North America, may have eaten willow leaves and twigs, or other trees growing in moist places, rising up to pull down branches and break them off or strip them. Some scientists believe that sloths may have supplemented their diet with meat, either taken from already killed animals, the sloths acting as scavengers and scaring away predators with their vicious claws and size when reared up, or killing animals with those same long, sharp claws, after rolling over a giant armadillo, for example, and stabbing its soft underbelly. There is less evidence for an omnivorous diet and more speculation, at this point.

Answer: bony "ossicles" acted like armor plating to ward off predators' attacks

Ground sloths had dermal ossicles, which were actually pieces of bone which occurred in the skin under the fur. They are rare in mammals. Among modern mammals, only armadillos have them. They are frequently seen in reptiles, though. The ossicles made the skin difficult to pierce and probably protected the sloth from the teeth and claws of its predators.

In any preserved skin of ground sloths, the ossicles have been found.

Answer: their tongues could reach out and grasp during feeding

At least some ground sloths had prehensile tongues. That doesn't mean a sloth could swing from it like a prehensile tail, but it meant the tongue was long and could reach and grasp to strip leaves and twigs off a branch, like an extra hand. A similar example on a living animal is the giraffe, which can stick its tongue far out and manipulate branches when it eats, to the surprize and enjoyment of zoo visitors on Youtube. Imagine being able to see a giant ground sloth at a zoo!

Answer: South America

Ground sloths evolved about 35 million years ago in South America. They are indeed rodents, like hamsters, which is where the quiz title came from. Their appearance on all fours is similar to a hamster also, and if they only fit in the palm of your hand or explored a tabletop, they'd be cute waddling little animals. Unfortunately...

But anyway, they began migrating to North America about 2 million years ago. At that time, there were small islands between the two continents. Miocene sloths are believed to have made their way north to North America across a land bridge and to the Antilles islands by crossing on land bridges or making short swims.

The last arrived during the Pleistocene, when the extinctions of most large mammals began.

Answer: aquatic or semi-aquatic

Thalassocnus branched off from other ground sloths. Its fossils are found in the Miocene and Pliocene periods. Unlike other prehistoric or modern sloths, they grazed on sea grass and seaweed, gradually adapting to an increasingly aquatic lifestyle. There was a gradual increase in the thickness and compactness of the ribs and long leg bones, to provide ballast.

As it could dive deeper, scratches on its teeth from sandy sea grass disappeared, as it fed on deeper grasses. Scientists believe it may have used its long claws to hook into the sea floor and help hold itself down.

A similar adaptation to sea life has occurred in the modern marine iguana.

Answer: no, they didn't actually live in the cave at the same time

Well, the theory was good at the time, but further investigation with radiocarbon dating showed that sloths and humans lived in the same cave, but not at the same time. Humans may have eaten sloths occasionally, since there are butchering marks on some other sloth bones, but it's not known if they hunted the sloth or came upon another animal's kill and chased it away. Sloths do not seem to have made up much of early humans' diet.

Answer: Carbon 14 dating showed the skin was 5,000 years old, and there were no further sightings

Patagonia, an isolated region of southern Argentina and Chile, might be where an animal could continue living hidden, and a 5,000-year-old well-preserved skin is amazing. Prof. Ameghino's discovery of Eberhardt's cave and others nearby turned up evidence that giant sloths and men did live at the same time.

But no other sightings have occurred, and scientists suggest that the perfect atmosphere in the cave made the skin appear fresh to a viewer not using dating techniques. The consensus is that ground sloths lived a long time in Patagonia, long enough to interact with modern humans, but unfortunately, not up to the present day.