Fossilized Footprints Show Ice Age Hunters Ganged Up on Giant Sloths

Alex McCelland, Bournemouth University
Alex McCelland, Bournemouth University

They just don't make sloths like they used to. Giant ground sloths from the Ice Age wielded razor-sharp claws and stood 7 feet tall, and new evidence suggests that humans—even children—stalked and hunted them.

By analyzing fossilized footprints found in the salt flats of New Mexico, researchers at Bournemouth University in the UK figured out how prehistoric humans managed to outsmart these furry behemoths. The tracks, which are between 10,000 and 15,000 years old, show two overlapping sets of footprints belonging to both man and beast. Researchers deduced that these early hunters aligned their footprints with the sloth's to avoid detection and sneak up on their prey. The findings were published in the journal Science Advances.

Human footprints inside of a larger sloth footprint
Matthew Bennett, Bournemouth University

"Getting two sets of fossil footprints that interact, that show you the behavioral ecology, is very, very rare," Matthew Bennett, one of the researchers at Bournemouth, told Reuters.

They also found another set of human footprints, leading researchers to believe that hunters traveled in packs and ganged up on the sloth, with one group distracting the animal from a safe distance while another attempted to land a fatal blow. The clue was in marks they dubbed "flailing circles," which suggested that the sloth rose on its hind legs and swung around to defend itself. Anywhere they found flailing circles, human footprints followed.

The presence of children's tracks also showed that hunting was a family affair, but it probably wasn't as fun (or as safe) as going to a modern-day zoo. The prints were taken from New Mexico's White Sands National Monument, which has the "largest concentration of human and Ice Age giant megafauna prints in the Americas," according to researchers. The remote part of the park where they conducted their research is not open to the public.

Modern sloths are related to the giant ground sloth, which went extinct about 11,000 years ago, likely due to over-hunting by humans, scientists say. The fossilized footprints were digitized and preserved for future research using 3D modeling techniques.

After 110 Million Years, This Spider Fossil's Eyes Are All Aglow

© Changkun Park, Electron Probe Micro Analyzer, Korea Polar Research Institute
© Changkun Park, Electron Probe Micro Analyzer, Korea Polar Research Institute

A big, hairy spider is enough to give anyone a fright. So you can imagine what a set of eight glowing eyes attached to a body like that might do to an arachnophobe's psyche. One such spider was discovered recently by researchers, but don’t worry—the iridescent-eyed arachnid has been dead for 110 million years.

As Popular Science reports, this rare, fossilized specimen was found in South Korea’s Lower Cretaceous Jinju Formation. The find was unusual for a couple of reasons. For one, spiders are not usually preserved in rock because the soft-bodied creatures decay easily. It’s also not every day that you see a long-dead spider with glowing eyes. On top of that, researchers found two well-preserved examples of these spiders, which were described in a recent issue of the Journal of Systematic Palaeontology.

Both specimens belong to Lagonomegopidae, an extinct family that predated jumping spiders. The glow is caused by a layer of tissue called tapetum lucidum, which coats the spider’s eyes and reflects light, allowing the spider to hunt at night with ease. Many animals have it—including cats, dogs, horses, deer, raccoons, and some modern spiders—but this is the first paper to describe its existence in a fossilized spider. The tapetum is crescent-shaped and “looks a bit like a Canadian canoe,” according to Paul Selden, a geology professor at the University of Kansas and co-author of the paper.

“Because these spiders were preserved in strange silvery flecks on dark rock, what was immediately obvious was their rather large eyes brightly marked with crescentic features,” Selden said in a statement.

The fossilized spider
Paul Selden

Researchers now want to go back and take another look at similar spiders preserved in amber, which are far more common than spiders fossilized in rock. The challenge is determining whether those specimens also have a layer of tapetum lucidum coating their eyes.

“Amber fossils are beautiful, they look wonderful, but they preserve things in a different way,” Selden said. “Now, we want to go back and look at the amber fossils and see if we can find the tapetum, which stares out at you from rock fossils but isn’t so obvious in amber ones because the mode of preservation is so different.”

[h/t Popular Science]

A (Still-Sharp) Medieval Sword Was Pulled from a Sewer in Denmark

Pipe layer Jannick Vestergaard and engineer Henning Nøhr hold up the sword they found.
Pipe layer Jannick Vestergaard and engineer Henning Nøhr hold up the sword they found.
Nordjyllands Historiske Museum (Historical Museum of Northern Jutland)

If the legend of King Arthur and Excalibur is anything to go by, anyone who successfully extracts a sword in a stone will be treated like royalty. The fable doesn’t say anything about the reward one gets for removing a medieval weapon from feces, though.

As Smithsonian reports, a pipe layer and an engineer recently found a sword from the medieval era while doing construction work on a sewer in Aalborg, Denmark’s fourth-largest city. The relic was plucked from a layer of waste that had accumulated atop an old slab of pavement that once ran through the city.

Most remarkably, the sword was still intact—and the blade still sharp. It’s about 3.5 feet long and of extremely high quality, according to archaeologists. The sword may have been used between 1100 and 1400, but the likeliest explanation is that it got separated from its owner sometime in the 14th century. “Findings from here have always pointed to the 1300s, so the sword must have ended up in the earth in this century,” archaeologist Kenneth Nielsen said in a translated statement.

The sword next to a tape measure
Nordjyllands Historiske Museum (Historical Museum of Northern Jutland)

It’s rare for such an important historical artifact to turn up in such an unlikely—and unhygienic—place. Swords were valuable and highly prized possessions, and they were treated as such. They were typically buried with their owners, but no graves are situated above the sewer where the weapon was found.

The country’s history offers some clues about what may have transpired, though. In the 1300s, power struggles and internecine war were common throughout Denmark. “The best explanation we can come up with is that the owner of the sword was defeated in a battle,” Nielsen told The Local Denmark. “In the tumult, it was then trod down into the layer of mud that formed the street back then.”

Similarly, a 14th-century sword was found in a Polish peat bog in 2017, and archaeologists suspect the owner either sunk into the marsh and met a grisly end, or merely dropped his weapon and was unable to retrieve it.

While these questions will likely remain unanswered, members of the public will have the chance to admire the Danish "sewer sword" in all its glory at the Aalborg Historiske Museum (Aalborg Historical Museum), which is located near the site where the sword was found. Fortunately for future visitors, it will be cleaned and preserved first.

[h/t Smithsonian]

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