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Description
Megalonyx jeffersonii

Ground sloths were among the most unique of all Pleistocene megafauna. Evolving in South America, they were the first of the South American megafauna to reach North America 9-10,000,000 years ago. Some 8,000,000 years before the two continents were linked by the Isthmus of Panama . They made it to the continent by island hopping from island to island in the Gulf of Mexico. The family Megalonychidae was among the most diverse of all ground sloth families, and its type species, Megalonyx jeffersonii, the Jefferson's Ground Sloth, was the most successful and wide-ranging of all Ground Sloths.

A President's Find:

In 1796, Colonel John Stuart sent then Vice President Thomas Jefferson a fossil femur fragment, ulna, radius, and 3 massive claws. They were discovered in Greenbrier County in Virginia (now West Virginia). Thomas Jefferson examined the bones, and in 1797, in a paper he presented to the American Philosophical Society (APS) in Philadelphia, he named them "Megalonyx" meaning "giant claw" in Greek. However, he never gave a diagnosis as to what this animal was. He at first attributed this to a lion, and even noted it to the paper to APS "that he was more than three times as large as the lion". However, in the postscript of his paper, he noted a similarity to an animal recently discovered in Paraguay called Megatherium, a gigantic sloth weighing in at around 4 tons.
However, in 1799, Caspar Wistar, an American anatomist correctly attributed the bones to be a sloth and not to a lion.
Extinction was an emerging view in natural history, however, Thomas Jefferson was a man who believed in a "completeness of nature". He believed that the creator (Jefferson was a deist) would not let there be an imbalance in nature and let a creature die off. When he became President, Jefferson had told the explorers Meriwether Lewis and William Clark to find evidence of live animals in the western United States. Of course, this made no headway and no living specimens were discovered/described by the expedition.
In 1822, some 23 years after Wistar identified the bones, he proposed naming this species "Megalonyx jeffersonii". French anatomist, Anselme Gaëtan Desmarest described it first during that same year, but Richard Harlan, an American naturalist formally described in 1825.

Evolution:

The Megalonyx genus had a variety of species throughout its 10,000,000 year reign. Its sister species, "M.leptostomus" lived till around 250,000 years ago, and was around half the size of Jefferson's Sloth. Another species, which evolved from M.leptostomus evolved into M.wheatleyi, even bigger than the preceding species. But the last, biggest, and most widespread of all was the type species, Jefferson's Ground Sloth.

Description:

It was fairly average size for a ground sloth. Around 10ft long and weighing in at around a ton. Compared to other ground sloths it had a more squared off head compared to other ground sloths, broadened peg-like designed to process plant material, and of course, massive claws used for manipulating branches and for defense. The hind limbs were flattened and they had a muscular tail they could have used as a prop to rear back on their hind limbs to bring the foliage towards their maw.

Range:

Fossils of this species range from as far south as Southern Mexico and as far north as Yukon and into Alaska. In fact the Jefferson's Ground Sloth was the only species of ground sloth to reach Alaska.

Behavior:

Fossils found in Iowa have shown evidence of parental care and even extended social behavior in these sloths. An adult individual was found in direct association with 2 smaller individuals with paleontologists theorizing that varying generations caring for their young.
By studying the only terrestrial pilosan alive today, the giant anteater, it could be extrapolated that these giant sloths carried their babies on their back until they were old enough to walk alongside their mothers. Their massive torsos would have made for a good spot to rest and stay safe from any potential predators.
Furthermore, in western Iowa, white-tailed deer fossils have been found alongside these sloths. It has been theorized that these two forest-going animals stuck close to one another for mutual protection.
Megalonyx and by extension, the Jefferson's Ground Sloth's, lived in a variety of habitats, however, recent studies have found the primary habitat would have been woodlands and forested areas. The environments of various deciduous forests would have suited this sloth well. Filling the niche of the large browsing animal eating a variety of plants in its habitat.
In a 2013 paper, it was found that the Megalonyx genus would have had a forest-oriented browser. It would have consumed woody plants, oak trees, and other woody branches like spruce trees. This was one of the largest browsers in the woodlands of North America. In fact, in parts of the American South, the sloth along with various proboscideans would have browsed upon the Osage oranges, a unique fruit found in parts of Texas and Oklahoma. Nowadays, few browsing animals can consume it so it just rots away, an example of anachronistic evolution as no browsers can consume it.

Extinction:

These sloths along with countless other megafauna would vanish around 10-11,000 years ago. Why they went extinct is largely believed to have been due to both climate change and human hunting. A fossil femur of a Jefferson's Ground Sloth found near Snowmount Village (near Aspen) in Colorado has shown evidence of human butchery dated to around 13,000 years ago.
Ground sloths would persist in the Caribbean for the next few thousand years, but by ~1600-1550 BCE, none would be left on the planet.

Despite the fact that this sloth had gone extinct some 11,000 years ago, its mark on paleontology and history is undeniable. Thomas Jefferson's description of this animal is largely credited as being the beginning of American Paleontology. And the find was not a dinosaur or a marine reptile, but a sloth.
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One of the most iconic sloths found in North America and it honestly needed a good facelift to bring it more in line with how it really looked.

It was made by LazardiK and his Sloth pack. However, I decided to give it a more accurate posture as well as a more accurate skull. I used artbyjrc 's Megalonyx for one of my refs, but also looked at various skulls/skeletal mounts of Jefferson's Ground Sloths and skull drawings/photos in various papers.

As I said before, this guy does great Paleoart:
Ground Sloths 2 - Megalonychids by artbyjrc on DeviantArt

FYI: The paper where I referenced the white-tailed deer was here:
A Ground Sloth, Megalonyx, from a Pleistocene Site in Darke Co., Ohio (core.ac.uk)

Will this be used in Past Meets Present, likely yes. I may change the genus/species depending on where I feature the episode. But, various Megalonychid sloths had a fairly universal body plan. I will change the skin and likely the skull depending on what species/material I have to work with.

ANYWAYS, hope you guys enjoy this, and I can tell you, come Friday, I'll have a bit of a surprise for you guys so, hope you guys are looking forward to that.

Original model and skin by LazardiK :
Jefferson's Ground Sloth (Lazardi) | ZT2 Download Library Wiki | Fandom

For Past Meets Present:
Past Meets Present (Pt4 is Up) - The ZT2 Round Table

Description
Megalonyx jeffersonii

Ground sloths were among the most unique of all Pleistocene megafauna. Evolving in South America, they were the first of the South American megafauna to reach North America 9-10,000,000 years ago. Some 8,000,000 years before the two continents were linked by the Isthmus of Panama . They made it to the continent by island hopping from island to island in the Gulf of Mexico. The family Megalonychidae was among the most diverse of all ground sloth families, and its type species, Megalonyx jeffersonii, the Jefferson's Ground Sloth, was the most successful and wide-ranging of all Ground Sloths.

A President's Find:

In 1796, Colonel John Stuart sent then Vice President Thomas Jefferson a fossil femur fragment, ulna, radius, and 3 massive claws. They were discovered in Greenbrier County in Virginia (now West Virginia). Thomas Jefferson examined the bones, and in 1797, in a paper he presented to the American Philosophical Society (APS) in Philadelphia, he named them "Megalonyx" meaning "giant claw" in Greek. However, he never gave a diagnosis as to what this animal was. He at first attributed this to a lion, and even noted it to the paper to APS "that he was more than three times as large as the lion". However, in the postscript of his paper, he noted a similarity to an animal recently discovered in Paraguay called Megatherium, a gigantic sloth weighing in at around 4 tons.
However, in 1799, Caspar Wistar, an American anatomist correctly attributed the bones to be a sloth and not to a lion.
Extinction was an emerging view in natural history, however, Thomas Jefferson was a man who believed in a "completeness of nature". He believed that the creator (Jefferson was a deist) would not let there be an imbalance in nature and let a creature die off. When he became President, Jefferson had told the explorers Meriwether Lewis and William Clark to find evidence of live animals in the western United States. Of course, this made no headway and no living specimens were discovered/described by the expedition.
In 1822, some 23 years after Wistar identified the bones, he proposed naming this species "Megalonyx jeffersonii". French anatomist, Anselme Gaëtan Desmarest described it first during that same year, but Richard Harlan, an American naturalist formally described in 1825.

Evolution:

The Megalonyx genus had a variety of species throughout its 10,000,000 year reign. Its sister species, "M.leptostomus" lived till around 250,000 years ago, and was around half the size of Jefferson's Sloth. Another species, which evolved from M.leptostomus evolved into M.wheatleyi, even bigger than the preceding species. But the last, biggest, and most widespread of all was the type species, Jefferson's Ground Sloth.

Description:

It was fairly average size for a ground sloth. Around 10ft long and weighing in at around a ton. Compared to other ground sloths it had a more squared off head compared to other ground sloths, broadened peg-like designed to process plant material, and of course, massive claws used for manipulating branches and for defense. The hind limbs were flattened and they had a muscular tail they could have used as a prop to rear back on their hind limbs to bring the foliage towards their maw.

Range:

Fossils of this species range from as far south as Southern Mexico and as far north as Yukon and into Alaska. In fact the Jefferson's Ground Sloth was the only species of ground sloth to reach Alaska.

Behavior:

Fossils found in Iowa have shown evidence of parental care and even extended social behavior in these sloths. An adult individual was found in direct association with 2 smaller individuals with paleontologists theorizing that varying generations caring for their young.
By studying the only terrestrial pilosan alive today, the giant anteater, it could be extrapolated that these giant sloths carried their babies on their back until they were old enough to walk alongside their mothers. Their massive torsos would have made for a good spot to rest and stay safe from any potential predators.
Furthermore, in western Iowa, white-tailed deer fossils have been found alongside these sloths. It has been theorized that these two forest-going animals stuck close to one another for mutual protection.
Megalonyx and by extension, the Jefferson's Ground Sloth's, lived in a variety of habitats, however, recent studies have found the primary habitat would have been woodlands and forested areas. The environments of various deciduous forests would have suited this sloth well. Filling the niche of the large browsing animal eating a variety of plants in its habitat.
In a 2013 paper, it was found that the Megalonyx genus would have had a forest-oriented browser. It would have consumed woody plants, oak trees, and other woody branches like spruce trees. This was one of the largest browsers in the woodlands of North America. In fact, in parts of the American South, the sloth along with various proboscideans would have browsed upon the Osage oranges, a unique fruit found in parts of Texas and Oklahoma. Nowadays, few browsing animals can consume it so it just rots away, an example of anachronistic evolution as no browsers can consume it.

Extinction:

These sloths along with countless other megafauna would vanish around 10-11,000 years ago. Why they went extinct is largely believed to have been due to both climate change and human hunting. A fossil femur of a Jefferson's Ground Sloth found near Snowmount Village (near Aspen) in Colorado has shown evidence of human butchery dated to around 13,000 years ago.
Ground sloths would persist in the Caribbean for the next few thousand years, but by ~1600-1550 BCE, none would be left on the planet.

Despite the fact that this sloth had gone extinct some 11,000 years ago, its mark on paleontology and history is undeniable. Thomas Jefferson's description of this animal is largely credited as being the beginning of American Paleontology. And the find was not a dinosaur or a marine reptile, but a sloth.
___________________________________________________________________________________________
One of the most iconic sloths found in North America and it honestly needed a good facelift to bring it more in line with how it really looked.

It was made by LazardiK and his Sloth pack. However, I decided to give it a more accurate posture as well as a more accurate skull. I used artbyjrc 's Megalonyx for one of my refs, but also looked at various skulls/skeletal mounts of Jefferson's Ground Sloths and skull drawings/photos in various papers.

As I said before, this guy does great Paleoart:
Ground Sloths 2 - Megalonychids by artbyjrc on DeviantArt

FYI: The paper where I referenced the white-tailed deer was here:
A Ground Sloth, Megalonyx, from a Pleistocene Site in Darke Co., Ohio (core.ac.uk)

Will this be used in Past Meets Present, likely yes. I may change the genus/species depending on where I feature the episode. But, various Megalonychid sloths had a fairly universal body plan. I will change the skin and likely the skull depending on what species/material I have to work with.

ANYWAYS, hope you guys enjoy this, and I can tell you, come Friday, I'll have a bit of a surprise for you guys so, hope you guys are looking forward to that.

Original model and skin by LazardiK :
Jefferson's Ground Sloth (Lazardi) | ZT2 Download Library Wiki | Fandom

For Past Meets Present:
Past Meets Present (Pt4 is Up) - The ZT2 Round Table